Electronics Material Officer Course
MODULE NUMBER TWO
LESSON TOPIC ONE
ELECTRONICS SAFETYMODULE TWO LESSON TOPIC ONE
LESSON TOPIC OVERVIEW
LESSON TOPIC ONE
This lesson topic presents information about duties and organizational relationships, the electronics division organizational manual and EMO relieving procedures.
The LEARNING OBJECTIVES of this LESSON TOPIC are as follows:
2.1 Identify references used for the administration of the electronics division safety program.
2.2 Describe the purpose, content, and responsibilities applicable to the electronics division safety program to include:
a. Safety organization/procedures
b. Electronics safety officer
c. Division safety petty officer
d. Safety hazard reports
2.3 Describe the hazards of electromagnetic radiation to include:
a. Hazards of Electromagnetic Radiation to Personnel (HERP)
b. Radio Frequency Burn Hazards to Personnel (RF Burn)
c. Biological, Thermal, and Neurological Effects to Personnel (RADHAZ)
d. Hazards of Electromagnetic Radiation to Fuel and other Flammable Material (HERF)
e. Hazards of Electromagnetic Radiation to Ordnance (HERO)
2.4 Describe the procedures for handling radioactive tubes.
2.5 Describe the procedures for working on energized/de-energized equipment.
2.6 Describe interior work area safety requirements to include:
a. Work benches
d. Equipment interlocks
e. Shorting probe
f. Rubber gloves and goggles
h. Portable electrical equipment
i. Three prong plugs
j. Grab rods
2.7 Describe the exterior work area safety requirements to include:
a. Warning signs and circles
b. Antenna shields
c. Antenna disconnect switches
d. Wire antennas
f. Handrails, grab rods and ladders
g. Safety harness and Safe-T-Climb (climber safety device)
The student should review the "LIST OF STUDY RESOURCES" and read the Lesson Topic LEARNING OBJECTIVES before beginning the lesson topic.MODULE TWO LESSON TOPIC ONE
LIST OF STUDY RESOURCES
To learn the material in this LESSON TOPIC, you will use the following study resources:
Written Lesson Topic presentations in the Module Booklet:
1. Lesson Topic Summary
2. Narrative Form of Lesson Topic
3. Lesson Topic Progress Check
1. Assignment Sheet
2. Answer Booklet
1. Shipboard Electronics Material Officer, NAVEDTRA 12969
2. ET Supervisor (ETC) Training Manual, NAVEDTRA 12410
3. COMNAVSURFLANT Maintenance Manual, COMNAVSURFLANTINST 9000.1(Series)
4. Safety Precautions for Forces Afloat, OPNAVINST 5100.19(Series)
5. Electromagnetic Radiation Hazards, OP3565 Volume I and II
6. Naval Ships' Technical Manual, Chapter 300
LESSON TOPIC SUMMARY
Lesson Topic One introduces you to safety as it pertains to the EMO and Electronics Safety Officer. You will learn what the safety organization is, what your responsibilities are, and what to look for in your spaces. The lesson narrative is organized as follows:
A. Introduction to Safety
B. General Electrical Safety Requirements
C. Electronic Work Benches
D. Electrical/Electronic Equipment
E. Rubber Matting and Sheeting
F. Hazards of Electromagnetic Radiation
LESSON TOPIC 2.1
INTRODUCTION TO SAFETY
The goal of the safety program is to prevent accidental injury or death, and prevent damage to equipment. Type commander requirements and command responsibilities are identified in the following paragraphs.
TYCOM requires that commands:
lDesignate a command electrical and electronic safety officer in writing
lImplement a comprehensive training program for all hands on hazards and safety precautions pertaining to shipboard electrical systems, equipment, and personal electrical and electronic equipment
lPeriodically test and inspect electrical equipment, electrical tools, and personally owned electrical and electronic equipment (accurate inventories of all such equipment must be maintained)
lEnsure proper and safe installation of electrical and electronic equipment
lEstablish an electrical tool issue room for central storage, control, and issue of portable electrical equipment and safety gear
The Commanding Officer is ultimately responsible for safety. The Commanding Officer must ensure that personnel know and comply with all safety precautions and procedures. Authority is delegated to subordinates for the execution of details.
The Safety Officer must ensure that the command's safety organization accomplishes the following:
lMonitor mishap prevention by investigating all mishaps and near mishaps
lEvaluate the effectiveness of the safety program by analyzing internal and external reports
lCoordinate distribution of safety information including "lessons learned" from official and non-official sources
lCoordinate shipboard training in general mishap prevention, including indoctrination of new personnel
lEnsure submission of occupational injury and illness reports to NAVSAFECEN
lPerform trend analysis of data on injuries and illnesses
lFollow up on reports of unsafe and unhealthy conditions in accordance with Navy Occupational Safety and Health (NAVOSH) Program Manual, OPNAVINST 5100.23(Series)
lTrack corrective action on safety and health items
lMaintain liaison with other commands and NAVSAFECEN in matters pertaining to mishap prevention
lCoordinate traffic and motor vehicle safety training
lCoordinate recreational and off-duty safety training
Electronics Material Officer
Personnel and equipment safety is a major responsibility of the EMO. Because of the inherent dangers of working on electronic equipment, safety precautions are an important part of the electronics training program. The EMO's responsibilities concerning safety generally include the areas of training, promotion, and enforcement. Specifically, the EMO's safety responsibilities are:
lEnsure that personnel engaged in operation and repair of electronic equipment follow safety precautions
lEnsure that required safety devices and warning signs are installed
lTrain electronics personnel in safety precautions and mishap prevention
lEnsure that electronic equipment is properly grounded
lAdvise the safety officer of safety training requirements
lServe as the divisional point of contact in coordinating and evaluating the unit's safety program
lDesignate a petty officer, preferably E-6 or above, as division safety petty officer
lInvestigate division mishaps and near mishaps and report unsafe or unhealthy conditions
lEnsure immediate action is taken to correct hazards and report findings
lEnsure that personnel receive mishap prevention training
lEnsure that adequate and effective personal protective equipment is provided for and used by division personnel
Division Safety Petty Officer
The division safety petty officer's responsibilities are:
lBe thoroughly familiar with all safety directives and precautions concerning the division
lConduct division mishap prevention training and keeping records in accordance with OPNAVINST 5100.23(Series), 5102.1(Series), and 5100.19(Series)
lAssist with mishap investigations, as directed
lRecommend improvements to the safety program
lAssist the division officer with implementing the safety program
lProvide technical advice on accident prevention within the division
lServe on the enlisted safety committee
lEnsure that prescribed personal protective equipment is provided and used by division personnel
lCorrect safety hazards noted on safety hazard reports
Supervisors must set good personal examples and ensure that safety precautions are strictly followed. All personnel must strictly observe safety precautions. Accident prevention is everyone's business. All personnel must:
lObserve posted operating instructions and safety precautions
lReport any unsafe condition, equipment, or material
lWarn others of hazards and failure to observe safety precautions
lWear approved protective clothing or use protective equipment as required
lReport any injury or evidence of impaired health
Post-accident investigations have revealed that the majority of accidents are caused by unsafe practices. Most of these practices are known beforehand to be unsafe and in violation of safety regulations. Other factors include fatigue, monotony, preoccupation at a critical moment (inattentiveness), mental and/or physical problems, improper supervision, and lack of motivation. All personnel, even "old salts", need to be reminded to work safely. Reports of senior electrical and electronics personnel involved in fatal accidents illustrate this point. People do not always act (or react) as they were trained or directed. Humans make mistakes. By their action or inaction they cause, or fail to prevent, accidents. In order to prevent accidents personnel must always be mentally and physically alert to potential hazards. Training, reminders, and good personal examples will create a climate of safety awareness. Use the electrical safety program checklist, Appendix B7-A in OPNAVINST 5100.19, to spot check your division's safety compliance. Your safety petty officer can help by conducting periodic safety inspections.
Type commanders require that the Electronics Doctrine contain a section on safety. This provides a ready reference to train personnel on general and ship-specific safety precautions. Safety Precautions for Forces Afloat requires that all personnel, when reporting aboard and annually thereafter, receive indoctrination on basic electrical safety. Annual electrical safety training must include the following topics:
lElectrical shock trauma
lEmergency medical trauma
Additionally, the following points should be emphasized:
lVisually inspect portable electrical equipment before using it. Look for damaged plugs, frayed cords, broken or missing ground connections, and other component defects.
lNever use portable electrical equipment if there is reason to believe it might be defective. Have it tested by authorized personnel prior to use.
lDo not complete unauthorized repairs or alterations.
lDo not use any personal electrical/electronic equipment aboard ship unless it has been inspected and approved by the ship's electrical or electronics shop according to ship's instructions.
lAlways report any shock received from electrical equipment, regardless of how slight.
OPNAVINST 5100.19 also requires that all electrical/electronics associated ratings receive annual Cardio-Pulmonary Resuscitation (CPR) training from an certified instructor. The recent extension of CPR qualification to two years does not change the annual requirement for electrical/electronic ratings. Track the CPR qualifications of your personnel to ensure annual requalification. It is easier to keep personnel certified if one of your technicians qualifies as a CPR instructor.
In addition to indoctrination and annual training, remember to schedule regular divisional training on electrical/electronic safety. To emphasize safety daily you can submit safety notes for the POD, post safety posters, and distribute safety publications (periodicals and pamphlets). Electrical safety posters are listed in EIMB General and NAVSUP 2002. If you use posters change or rotate them regularly to draw attention to them. A variety of warning signs are also required. You will find these listed in the EIMB, NSTM Chapter 300, and RADHAZ publications. Additionally, when a mishap occurs, conduct training to prevent future occurrences.
Written safety precautions should include information concerning electric shock. Ensure the following general warnings are stressed:
lVoltages as low as thirty volts can be fatal.
lDanger of electric shock is much greater aboard ship than ashore.
lThere is very little difference between the voltage it takes to create a slight tingle and a fatal shock.
Factors determining the extent of body damage resulting from electric shock are:
lThe amount and duration of current flow through the body
lParts of the body involved
lIn the case of alternating current (AC), the frequency of the current
Generally, the greater the current or the longer the current flows, the greater the body damage.
Body damage is more likely to occur when the current flow is through or near nerve centers and
vital organs. An alternating current at a frequency of 60 Hz is considered slightly more dangerous than an AC at a lower frequency, or than direct current (DC). This is because ventricular fibrillation is produced with just 60 to 100 mA of 110 to 220 volts AC at 60 Hz, while 300 to 500 mA of DC voltage is required for the same reaction. However, the same precautions that apply to 60 Hz AC also apply to DC. Humans differ in their resistance to electric shock. A current flow that may cause only a painful shock to one person can be fatal to another. Table 2-1.1 shows the effects of 60 Hz current flowing through the body. Tests show that the resistance of the human body may be as low as 300 ohms under unfavorable conditions such as those caused by salt water and perspiration. Therefore, it is possible for a voltage potential as low as thirty volts to cause a fatal 100 mA current flow through the body.
Table 2-1.1 Effects of 60 Hz Current
║ CURRENT │ EFFECTS ║
║ Less than 1 mA │ No sensation ║
║ 1 - 20 mA │ Mild sensation to painful shock, may ║
║ │ lose control of adjacent muscles ║
║ │ between 10 and 20 mA ║
║ 20 - 50 mA │ Painful shock with probable loss of ║
║ │ control of adjacent muscles ║
║ 100 - 200 mA │ May cause ventricular fibrillation, ║
║ │ which results in almost immediate ║
║ │ death ║
║ Over 200 mA │ Severe burns and muscular contractions ║
║ │ so severe that the chest muscles clamp ║
║ │ the heart and stop it for the duration ║
║ │ of the shock ║
GENERAL ELECTRICAL SAFETY REQUIREMENTS
Safety requirements concerning various shop and work areas aboard ship are prescribed by the Safety Precautions for Forces Afloat, OPNAVINST 5100.19; Naval Ships' Technical Manual, Chapters 300, 313, 400, and 634; and the EIMB, General, NAVSEA SE000-00-EIM-100. You must ensure that the following general safety precautions are complied with:
lDo not touch a conductor, until it has been verified that it is deenergized.
lObey all warning signs; read equipment warning labels before use.
lDo not energize any equipment that is tagged out. Properly clear the tag first.
lUse authorized equipment to perform maintenance work.
lClose all fuse boxes, junction boxes, switch boxes, and wiring accessories.
lNever operate a switch with the other hand on a metal surface.
lNever use outlets that appear to be burnt. Do not use equipment with worn/damaged cords or crushed/damaged plugs.
lWhen using a metal cased tool, ensure it is equipped with a three prong plug and three conductor cord. Verify that the ground prong extends beyond the power blades.
lWear rubber gloves when using metal cased portable electric equipment or hand held portable tools in hazardous conditions (e.g., wet decks and bilges). Wear leather gloves
over rubber gloves when work being done could damage the rubber gloves.
lEnsure portable electric equipment is inspected and has a current tag attached.
lOnly use explosion proof electrical equipment in explosive atmospheres.
lDo not run cords over sharp objects, chemicals, or hot surfaces.
lDo not join more than two 25-foot extensions cords together. Single length extension cords up to 100 feet are permissible.
lUse a voltmeter or voltage tester to ensure that equipment or circuits are deenergized.
WORKING ON DEENERGIZED EQUIPMENT
The best way to avoid electrical hazards is to completely deenergize circuits on which work must be done. As a division officer, you will sign Tag Guide Lists (TGL) that will be used to tagout equipment. The TGL identifies how to isolate power from the circuit. Circuits are deenergized by opening all power supply circuit breakers/switches or removing appropriate fuses through which power can be supplied. Tagout procedures were covered in SWOS Division Officer Course. You must ensure that these procedures are strictly complied with. Familiar yourself with SORM, type commander, and unit tagout instructions.
Checking for Energized Circuits
Technicians must minimize access to open equipment by posting signs, erecting barricades, or securing the covers of unattended equipment. The following precautions ensure that a circuit is deenergized:
lFirst, a measurement is taken with a voltmeter or voltage tester across power source terminals of a known energized circuit to ensure that the meter is working properly.
lNext, the same meter is connected across the power source terminals and from each terminal
to ground on the equipment to be worked on to verify that it is deenergized. Both metering
and control circuits, as well as power circuits are checked. Test lead connections must be tight to avoid shock and fire hazards.
lFinally, the voltmeter or voltage tester is rechecked on the known energized circuit to ensure that the meter is still working properly.
Technicians who work on circuits that use large capacitors, pulse forming networks, etc. must use an authorized safety shorting probe to discharge the circuits. Shorting probes should be located in electrical/electronic equipment spaces (e.g., by switchboards, in CIC, and in radar rooms). Figure 2.1-1 shows the approved shorting probe with mounting assembly.
Figure 2.1-1 Shorting Probe and Holder Assembly
Because of possible misuse of the threads in the handhold section of the probe, NAVSEA has recommended that a #20 nylon screw be installed in the handhold end (EIB 932). Also, the head of this screw must be cut off after installation to prevent removal. Inspect shorting probes for the following:
lThe grounding clip is soldered to the ground cable
l#20 nylon screw is properly inserted
lThe band for the ground strap is covered with heatshrink
When using the general purpose safety shorting probe, technicians must connect the grounding clip first. If necessary, they scrape the paint off the grounding metal to make good contact. Then, while holding the safety shorting probe by the handle behind the protective shield, the end of the metal rod is brought into contact with the point to be shorted. Each point should be shorted to ground several times to ensure that the circuit is completely discharged. Technicians must be extremely careful that they do not touch any of the metal parts of the safety shorting probe while touching the probe to a "hot" terminal. Some electronic equipment have built-in special purpose safety shorting probes. These probes are not general purpose, and are to be used only with the equipment with which they are provided, as directed by equipment technical manuals. Ensure that they are not removed and used elsewhere.
WORKING ON ENERGIZED EQUIPMENT
Energized electrical equipment shall not be disassembled nor undergo any maintenance without approval by the Commanding Officer. Exceptions to this policy are as follows:
lWhen approved instructions issued by higher authority (equipment technical manuals, PMS procedures, or an established troubleshooting procedure) permit opening or inspecting equipment in the course of performing maintenance, routine testing, taking measurements, or making adjustments that require equipment to be energized
lWhen external test points are provided on an instrument panel
In addition to the general precautions cited previously, the following precautions must be observed for circuits greater than or equal to thirty volts:
lPersonnel must never work on energized equipment alone. A safety observer must be present. The safety observer must be CPR qualified and know how to deenergize the equipment.
lWorkers shall not wear watches, rings, watch chains, metal articles, or loose clothing that might accidentally contact energized circuits. Clothing and articles shall be as dry as possible.
lThe deck or standing surface must be insulated from ground with insulating material (rubber mat or rubber blankets or, when these are not available, dry wood, dry canvas, dry phenolic material, or even several layers of heavy, dry paper. Insulating materials must be large enough, dry, and have no holes or embedded conducting material.
lIf the work permits, rubber gloves should be worn. If not, a rubber glove is worn on the hand that is not handling tools. When technicians work with portable electrical tools in damp locations, or on energized equipment, they must wear electrical grade insulating rubber gloves. Technicians wear leather gloves over the rubber gloves when the rubber gloves could be cut by sharp or abrasive objects. Rubber gloves must be stowed in the original box. Preventive maintenance must be performed on the gloves prior to issue and stowage. Technicians must avoid folding the gloves frequently to prevent cracks that would reduce insulating capability.
lA faceshield or spectacles must be worn to protect from flying molten particles and intense heat produced by short circuits.
lMetal on handheld tools must be covered with electrical insulating material.
When work is particularly hazardous (e.g., involves switchboard interiors or other cubicles where exposed energized bus bars are in the vicinity of the work) or the work requires contact by tools to energized components, the following precautions must also be taken:
lStation personnel with communications, as necessary, to ensure the circuit can be immediately deenergized in an emergency.
lProvide insulated barriers between work and any energized metal parts adjacent to the work area, as practical.
lAttach a nonconducting safety line or equivalent to a safety harness or around the waist of the person doing the maintenance. Line tender should be a safe distance outside the barrier.
lErect barriers to keep unauthorized personnel out of the work area. Barrier must be a minimum of three feet from the energized electrical work site. The sign shown in Figure 2.1-2 must be placed at the barrier.
│ DANGER │
│ Working on Energized Equipment │
│ Unauthorized Personnel │
│ Keep Out │
Figure 2.1-2 Worksite Danger Sign
GENERAL INSIDE WORK AREA REQUIREMENTS
The following rules must be observed for all inside work areas:
lAll electronic spaces will be equipped with authorized safety shorting probes.
lRadioactive tubes will be properly identified and stowed, and a spill kit available.
lWarning signs and posters concerning high voltage, safety precautions, operating instructions, rescue breathing signs, radio frequency radiation hazards, etc., will be posted in or near all spaces where electronic equipment is installed or repaired.
lOperational voice communications between all electronic spaces is required for emergency communications: X6J, 22MC, or J-dial.
lEmergency lighting must be installed.
lRubber gloves capable of insulating against voltages up to 17,000 volts and tested in accordance with PMS must be readily available to electronics personnel.
lA portable CO2 fire extinguisher must be readily available.
lEquipment having multiple voltage sources must be labeled with a multiple source warning label. A switch to disconnect equipment from power and synchro voltages is also required.
lPortable electrical equipment and power tools must be grounded through the use of an approved three-prong plug, or must be double insulated.
lNo unauthorized stowage is permitted (e.g., fan room or radar room used for stowage).
lAll personally owned electrical equipment shall be inspected and tagged before use aboard ship and reinspected at prescribed intervals in accordance with ship's instructions.
lShip's tag-out procedures shall be strictly enforced at all times.
lUse only one hand when working on or in close proximity to live circuits.
lHazardous materials must be properly stowed, used, and disposed of.
lEyewash facilities must be located in spaces where corrosive material is present (e.g., hazardous material lockers, ultrasonic cleaners, and battery lockers)
GENERAL OUTSIDE WORK AREA REQUIREMENTS
The following rules must be observed for all outside work areas:
lRequired warning signs (e.g., Danger Stack Gas, Danger High Voltage) must be properly posted. Placards and signs are listed in Shipboard EMO, NAVEDTRA 12969.
lAntenna shields/cages must be properly constructed and installed.
lAntenna disconnect switches must be installed as required.
lWire antennas must be properly constructed and installed, and meet all safety requirements.
lNonskid deck covering must be properly installed.
lThe proper safety harness must be used for working aloft or over the side.
lThe Saf-T-Climb fall prevention system must be properly installed and bonded.
lPersonnel aloft procedures must be strictly followed.
lRadiation hazards must be recognized by personnel and steps must be taken to correct hazardous situations.
lEquipment and ladders must be bonded to ship's ground, in accordance with MIL-STD-1310.
Aloft is defined as any mast, stack, mack (combination mast/stack), or kingpost. In addition to personnel falling, other hazards associated with working aloft are falling objects, radiation burns, and asphyxiation from stack gases. To go aloft your technicians must obtain permission from the Officer of the Deck (OOD) using a Working Aloft Check Sheet (Appendix C8-B in OPNAVINST 5100.19C). When the ship is underway, the Commanding Officer's permission is required to go aloft. The OOD will ensure the following:
lSignalman break KILO for personnel working aloft and KILO THREE for personnel working aloft and over the side
lShips in the vicinity are notified that personnel will be working aloft
lPrior to commencement of work and every fifteen minutes after, the following is passed over the 1MC: "There are personnel working aloft. Do not rotate or radiate any electrical or electronic equipment while personnel are working aloft aboard USS ."
Also, all radio transmitters and radars that pose radiation hazards are placed in standby and a sign placed on the equipment that reads: "Secured. Personnel aloft. Date , Time , Initials ." See NAVSEA OP3565 Volume One for fixed and moving beam exposure distances and times. Additionally, on aviation capable ships your technicians must understand the importance of Foreign Object Damage (FOD) control. After completing work topside, all tools and materials must be removed, as they may cause damage to aircraft or injury to personnel. Metallic items left in these areas may also create electromagnetic interference (EMI).
Ensure that technicians working aloft follow these rules:
lUse a climber sleeve assembly in conjunction with the safety harness where a climber safety rail is installed. A PMS check must be completed on both, immediately prior to use.
lAttach safety lanyards to all tools, if practicable. Never hand carry tools up and down ladders. Rig a line and raise/lower tools in a container.
lStop work when the ship begins to roll in excess of 10°, or to pitch in excess of 6°, when wind speed is greater than 30 knots, and when an ice storm/lightning threatens.
lThe petty officer in charge marks off an area below the zone of work and keeps all unnecessary personnel clear.
lRead safety placards posted in the area prior to commencing work.
lEnsure there are no stack gases present or don/have available an OBA (per unit instruction).
lWhen performing hot work, replace personal safety and staging/boatswain chair fiber lines with wire rope. Personal safety lines will be CRES (Corrosion Resistant Steel) wire rope.
lWear a parachute type safety harness with a safety lanyard, working lanyard, and tending line (as required) with double locking snap hooks. The harness will be inspected in accordance with established PMS prior to use.
A climber safety rail will be installed at each permanently installed topside ladder on masts, kingposts, and other similar topside structures that provides access to a fall-hazard location at which a person is expected to wear a safety harness (General Specifications for Navy Ships, Section 622). Climber safety rails are installed in accordance with NAVSHIPS Drawing 80064-804-4563125, Rev. C, and bonded in accordance with MIL-STD-1310. Where safety rails are installed and where a climber must transfer from one ladder to another, or from a ladder to a platform, padeyes will be provided to enable the climber to make a transfer, while tethered at all times to either a padeye or climber safety rail. NAVSHIPS drawing 80064-804-4563125 Rev C, states that all climber safety rails must be made of CRES steel. Obtain parts availability information from FTSC, RSG, SIMA, or NAVSAFCEN. Where rigid-rail type installation is not practical (i.e., for ladders less than twelve inches wide or peg-rung ladders on pole masts), a retractable-wire type installation is used. The fall prevention device is available through the national stock system. It must be bonded in accordance with MIL-STD-1310.
MULTIPLE SOURCE LABELS
A potential electrical shock hazard may exist in equipment powered from multiple sources, even when the main power is turned off. Multiple sources include primary/alternate power connections and synchro or gyro inputs. Multiple source equipment should have a warning label (Figure 2.1-7) attached that lists all incoming power circuits, identification of the power disconnect switch, and power disconnect switch location. Technicians must complete and attach labels in a conspicuous location on equipment. Drawings, manuals, instruction books, etc., should be used to ensure that the information is accurate. The label can be marked with pencil or felt tip pen however, a ball point pen or type is more durable.
Figure 2.1-7 Multiple Source Warning Label
SAFETY CUTOUT SWITCHES
Electronic equipment connected directly to the ship's electrical power distribution system must have switches to disconnect the equipment from all power sources. These switches must be located in the space where the equipment is located. When practical, electronic equipment distribution panels or boxes with switches will be used. Single disconnect switches should be located as close as practical to the equipment they serve. All remote equipment of an electronic system will have safety disconnect switches that allow independent power disconnect.
Electronic equipment with inputs of thirty volts (RMS1) or greater and that cannot be disabled by the system main power switch, will have disconnect switches or protective devices and warning signs. Radar indicators are included in this requirement. The disconnect switch for a radar indicator will be installed as close as practical to its associated indicator.
1AC voltage (E) is normally specified in terms of RMS value, Erms= Epeak x .707.
Antenna Safety Disconnect Switch
Safety disconnect switches should be installed for all rotatable antennas (except submarine and ECM antennas) to disable antenna rotation and equipment radiation prior to personnel entering the antenna swing circle. The antenna safety disconnect switch should be located as near the antenna as practical and be easily accessible. The disconnect switch should not have bypass capabilities except for systems that require a battle short switch.
References regarding multiple source labels and safety cutout switches are EIMB General, EIMB
Installation Standards, EIMB RADAR, and General Specifications for Navy Ships.
RADIOACTIVE SPILL KITS
The Hazardous Materials Information System (HMIS) lists radioactive tubes, proper stowage techniques, and disposal procedures. NAVSUP Publication 485 contains detailed custody procedures. See your safety officer to inquire about local regulations. References on radioactive tubes are Department of Defense Hazardous Materials Information System (HMIS), Radiation Health and Protection Manual, Afloat Supply Procedures, EIMB General and Radiac, Safety Precautions for Forces Afloat, and NSTM Chapter 400. All equipment containing radioactive tubes must have a standard warning label attached to the equipment where it would be noted upon entry into the equipment for maintenance. If an electron tube containing radioactive material is broken, follow the basic procedures for cleaning the area covered in the EIMB General, Section 3. A radioactive spill kit with all the materials required to clean the area quickly and properly is required. The ship must have at least one radioactive spill disposal kit for electronic spaces. More may be needed, depending on the number and location of spaces in which radioactive tubes are used or stored. Each kit should contain the items in Figure 2.1-3.
Figure 2.1-3 Radioactive Spill Kit
Container Must be large enough to hold all clean-up materials and pieces of broken radioactive tubes, and must be airtight. A three-pound coffee can with a plastic lid or 30/50 caliber ammo box will serve as a suitable container. The container shall be clearly marked "RADIOACTIVE SPILL DISPOSAL KIT."
Rubber gloves Two pairs of surgical latex gloves to prevent contact with contaminated material.
Forceps or Used for picking up large pieces.
Masking tape One roll of 2-inch-wide tape for picking up small pieces.
Gauze pads or One stack of 4-inch gauze pads (50 pads or more) for
rags wiping down the area. Sponges are NOT to be used.
Container of water A small container of water (approximately 2 ounces) in an unbreakable container, for wetting the gauze pads or rags.
Boundary rope and Used for marking the contaminated area.
Dust masks Disposable dust masks for protection from inhalation of dust.
Radioactive For labeling the material to be disposed of. (These
material stickers can be locally manufactured).
2 12-inch plastic For containing used materials.
Procedures Step-by-step clean up procedures should be included in each radioactive tube disposal kit.
Other items As recommended by type commander and the fleet training group.
The greatest danger from wet cell (lead acid) batteries is hydrogen gas produced during the charging of the battery. All flames and sparks or flame/spark producing items must be kept away from wet cell batteries. Eye and skin protection must be worn. An eyewash station must be located in the space. Lead-acid and alkaline batteries (nickel-cadmium, silver-zinc, nickel-iron, silver-cadmium, nickel-zinc), lithium, and dry cell batteries (Lelanche, mercury, and low-temperature cells) must be containerized for shore disposal. Check with your safety officer regarding disposal at sea. Ensure that personnel do not empty electrolyte from batteries. Personnel should never pierce, crush, burn, dismantle, or alter batteries. Corneal burns or blindness can occur with exposure to acidic battery electrolytes when batteries vent.
Nickel Cadmium Batteries
Nickel cadmium (NiCad) batteries must only be charged in series, never in parallel, and with a proper constant current charging rate. They must be maintained at a temperature below 113°F if possible, and short circuits must be avoided. References on battery stowage, charging, and disposal are EIMB General, Safety Precautions for Forces Afloat, Afloat Supply Procedures, and DOD Hazardous Materials Information System (HMIS).
Mercury batteries can explode if misused. The following safety precautions must be taken:
lNever discharge a mercury cell battery after its voltage has dropped below 70% of its normal voltage capacity.
lNever place a direct short on a mercury cell battery.
lDiscard spent batteries as soon as possible at the first shore installation.
lStore batteries in a well-ventilated, cool, fireproof area.
Lithium batteries are potentially hazardous. Use of lithium batteries is only allowed when no other safer, environmentally approved battery will do the job. Lithium battery approval extends to a specific application and no other. Lithium batteries must not be tampered with before, during, or after discharge. Lithium batteries can cause fires and even explode while rapidly discharging and up to thirty minutes after a rapid discharge. The type of accident most likely to occur, however, is the battery venting toxic gases, such as sulfur dioxide gas. Sulfur dioxide gas causes severe irritation to eyes and mucous membranes. The sulfur dioxide forms sulfurous acid when it comes in contact with moist membranes, can cause fluid build-up in the lungs, and can cause a person to stop breathing. Corneal burns or blindness can occur with exposure to liquid sulfur doxide. Whatever the state of charge, technicians must never pierce, crush, burn, intentionally drop, dismantle, modify, or carelessly handle lithium batteries. Lithium batteries must not be short circuited, charged, or used in any equipment other than the equipment specified for the battery.
POLYCHLORINATED BIPHENYLS (PCB)
Most transformers, capacitors, and similar components contain coolants, usually in the form of oils. Some of these coolants contain polychlorinated biphenyls or PCBs. PCBs are toxic to people and the environment. Restrictions have been placed on their manufacture and use. The U.S. Navy implemented a program in 1981 to control the use of PCBs. PCBs are very stable chemicals with many favorable characteristics, including high heat capacity, non-corrosivity, low flammability, and low electrical conductivity. However, PCBs cause adverse health effects, including irritation to the skin, eyes, and lungs, during even relatively brief exposures. PCBs ingested by people or animals are stored in fat tissues and can cause metabolic defects and tumors. PCBs can be absorbed through the skin and, at higher temperatures, vaporize into a toxic air contaminate. Ensure that technicians are trained in the potential hazards of PCBs. NAVSEA has distributed a list of components that contain or are suspected to contain PCBs. These items must be labeled, and a contingency plan developed in case of a leak or spill. Detailed information on PCBs is provided in the Shipboard Management Guide for Polychlorinated Biphenyls (NAVSEA S9593-A1-MAN-010).
Technicians who smoke while using volatile cleaning solvents are inviting disaster. The navy does not permit the use of gasoline, benzene, ether, or similar solvents for cleaning purposes because they present potential fire or explosive hazards. Only non-volatile solvents will be used to clean electrical or electronic equipment. Most cleaning solvents can also damage the human respiratory system. Technicians must observe the following precautions:
lDo not work alone in a poorly ventilated compartment.
lDo not use carbon tetrachloride. This is a highly toxic compound.
lDo not breathe directly over the vapor or breathe any cleaning solvent for prolonged periods.
lDo not spray cleaning solvents on electrical windings or insulation.
lDo not apply solvents to warm or hot equipment since this increases the toxicity hazard.
lUse a blower or a canvas wind chute to blow air into a compartment in which a cleaning solvent is being used.
lOpen all usable port holes and place wind scoops in them.
lPlace a fire extinguisher close by, ready for use.
lIf feasible, use water compounds instead of other solvents.
lWear rubber gloves to prevent direct contact with solvents.
lUse goggles when a solvent is being sprayed.
lHold the nozzle of the solvent close to the object being sprayed.
If using water compounds is not possible, inhibited methyl chloroform (also known as 1, 1, 1 and Trichloroethane) should be used instead of carbon tetrachloride. Methyl chloroform is a halogenated hydrocarbon extensively used as a solvent. It is an effective cleaner and safe when used with adequate ventilation and observing fire precautions. Direct inhalation of inhibited methyl chloroform vapors must be avoided. When properly used its vapors have a low order of toxicity. However, vapors of this solvent, especially when sprayed or heated, will readily accumulate in confined spaces and increase the chance of harmful exposure. Liquid cleaners are toxic if taken internally and when heated separate into subproducts which may be more toxic. For additional information refer to EIMB General, Safety Precautions for Forces Afloat, Hazardous Materials Information System (HMIS), and NSTM Chapters 100 and 670.
General Specifications for Navy Ships, Section 665, states that the only authorized workbench for repair of electrical/electronic equipment in electrical/electronic work spaces is the one shown in NAVAIR Drawing 63-A-114J. This workbench is illustrated in Figure 2.1-4. The top and front of electrical/electronic workbenches, kneeholes, and all other exposed metal areas must be insulated with 1/8-inch approved high pressure laminate. The brand name of this material is BENELUX or ARBORON. Handles must not be made of metal. The deck surrounding the workbench must be
insulated with electrical grade matting. To further reduce the chance of electric shock:
lBond and ground the workbench in accordance with MIL-STD-1310
lInstall a grounding bus for maintenance purposes
lPost a warning sign above the workbench that reads:
│ -DANGER- │
│ ELECTRIC SHOCK │
│ DO NOT TOUCH ENERGIZED CIRCUITS │
lInstall a disconnect switch to secure power to the workbench in case of electric shock (GENSPECS). The disconnect switch should be installed in the same compartment but away from the workbench. The switch must be labeled as the workbench disconnect switch.
lA sign showing instructions for rescuing personnel from electric shock must be posted. It is locally produced. This sign is shown in Figure 2.1-5.
Figure 2.1-4 Authorized Electrical/Electronic Workbench
A - _" Benelux 401
B - _" Laminate
Figure 2.1-5 Electrical Safety Sign for Electrical/Electronic Workbenches
The following are references on workbench safety:
lNAVAIR Drawing 63-A-114J
lCOMNAVSEASYSCOM WAHINGTON DC 151016Z APR 96
lShipboard Bonding Grounding and Other Techniques for Electromagnetic Compatibility and Safety
lGeneral Specifications for Navy Ships
lTest Equipment Stowage Guide
lElectronic Information Bulletin 015
ELECTRICAL/ELECTRONIC EQUIPMENT SAFETY
NSTM Chapter 300 Electric Plant - General addresses certain topics common to all types of electrical equipment, namely, sources of information, safety precautions, insulation, and maintenance. Do not assume that this manual does not apply to electronics. Chapter 300 is the definitive document on electrical safety. You must be familiar with it.
PERSONAL ELECTRICAL/ELECTRONIC EQUIPMENT
All personal electrical and electronic equipment brought aboard ship must be inspected by designated personnel. Approved equipment is labeled with a tag, tape, or sticker to indicate that it has been safety checked. The interval between safety inspections will not exceed six months. Designated electricians perform safety checks on electrical equipment. Designated electronics technicians perform safety checks on electronic equipment.
NSTM Chapter 300 states that "Personally-owned equipment/appliances such as portable radios, electric shavers, curling irons, hair dryers, hobby equipment, etc. are not of standard issue. Personal equipment can be approved for shipboard use when adequate government-owned equipment is not available to meet the need and the equipment has been inspected by the electrical/electronics shop and passes inspection for safe, rugged construction and test requirements of paragraph 300-188.8.131.52. Any personal equipment which fails to pass this inspection and testing must be appropriately modified to meet these requirements or its use shall be forbidden aboard ship. Final acceptance or rejection is at the discretion of the officer in charge of the inspecting shop. Additionally, electronic equipment that is not double-insulated or that does not have a case and handle made of non-conducting material and does not pass a inspection for rugged, safe construction and have a minimum of 1W DC resistance from any phase conductor to any exposed metal, part, or metal chassis must have a built-in power transformer that completely isolates the primary or line side of the transformer from the secondary or equipment side.
All hands must request permission from their division officer/chain of command in order to bring personal electrical/electronic equipment aboard. A request form, similar to Figure 2.1-6 (locally made), can be used for this purpose. The following personally-owned or non-navy-standard equipment is prohibited aboard ship:
Fans Portable extension cords Immersion-type water heaters
High intensity lamps Reading lamps Portable air conditioners
Electric blankets Heating pads Electric heaters
Electric power-driven tools Heat/sun lamps Portable refrigerators
(except those specifically Hot plates and griddles Portable extension lights
used as hobby tools) Electric clocks Microwave ovens
Figure 2.1-6 Personal Electrical/Electronic Equipment Request
│From: (Name, Rank/Rate) │
│To: Division Officer │
│Via: Electrical Officer/Electronics Material Officer │
│Subj: PERSONAL ELECTRIC/ELECTRONIC EQUIPMENT REQUEST │
│1. I request permission to have on board the following personal │
│electrical/electronic equipment. If approved, I understand I am to │
│keep it in good physical condition and have it reinspected every six │
│months and when damaged or altered. │
│Equipment Model │
│Make Serial No. │
│First Endorsement │
│From: Electrical Officer/Electronics Material Officer │
│To: Division Officer │
│1. The equipment listed above has been inspected and meets the │
│minimum safety requirements for shipboard use. The equipment │
│has been tagged and entered in the ship's personal electrical/ │
│electronic equipment data base. │
│Electrical Officer/ │
│Electronics Material Officer │
│Second Endorsement │
│From: Division Officer │
│To: (Name, Rank/Rate) │
│1. The equipment listed above is authorized for use on board. It │
│must be turned in for inspection every six months or when altered or │
│damaged. Failure to comply could result in the removal of the │
│equipment from the ship. │
│Division Officer │
As the electronics safety officer, how can the EMO effectively manage personal electronic equipment? Maintain a data base on personal equipment. Ensure that personnel report additions, changes, and deletions. Notify personnel in possession of equipment that is due or overdue for safety checks. Hold training on personal equipment safety. Personally inspect spaces for compliance.
There are other safety checks required in addition to those conducted semi-annually on personal electrical/electronic equipment. These safety checks are done in accordance with MRCs. Table 2.1-1 lists checks required and recommends guidelines. For more information about electrical safety requirements for portable and mobile equipment, see NSTM Chapter 300. Note in particular that:
lPlugs with metal shells are prohibited aboard ship.
lPortable extension cords used to connect 115VAC/60Hz single phase to portable equipment must have a ground conductor.
lSpliced portable cables are extremely dangerous and will not be used.
lSingle phase 115VAC mobile equipment that is permanently located and energized more than 50% of the time must be connected to a separate single phase circuit through an isolation transformer supplied by the lighting distribution system. Examples: copiers, personal computers and peripherals, soda machines, ATMs. Exceptions are temporary and must be in compliance with NSTM 300-184.108.40.206.
lPower must be switched off before inserting or removing a plug from a receptacle. Portable equipment must be connected to an extension cord before connecting the extension cord to the receptacle. An extension cord must be unplugged from the receptacle before unplugging the portable equipment cord from the extension cord.
lEnsure cables do not present a trip hazard and that no more than two 25-foot extension cables are joined together. Only approved 25-foot extension cords are to be used.
lApproved 100-foot cords are authorized for use on flight, hanger, and well decks, and floating drydock basins.
RUBBER MATTING AND SHEETING
To protect personnel from electric shock, ensure that approved floor matting is installed over metal and wood decks in electrical and electronic spaces. There are two types of deck covering to prevent electrical shock: approved deck material (e.g., tile) covered by portable or runner type matting in electrical hazard areas or electrical grade sheet cemented over the entire deck.
Table 2.1-1 Electrical/Electronic Safety Tag Information
│ EQUIPMENT TYPE │
│TEST │PERSONAL │SHIP'S │
│APPLICABLE │S-1R │N/A │A-6, A-7, M-2, M-4 │
│MRC │ │ │ │
│PERIODICITY │4-8 MONTHS │NOT TO EXCEED │A-6/A-7: 3-5 QUARTERS │
│ │ │SIX MONTHS │M-2/M-4: 3-6 WEEKS │
│DATE │NOTE DATE CHECKED ON TAG, TAPE OR STICKER TO AVOID CONFUSION│
│ │AS, E.G., 17SEP95. IF ONLY MONTH/YEAR HAS BEEN NOTED, USE │
│ │1ST DAY OF MONTH NOTED TO DETERMINE DATE DUE. │
│LOCATION OF TAG │TAG MAY BE HUNG ANYWHERE ALONG CORD. │
│RECOMMENDED TAG │MRC#, DATE │EQP SERIAL#, │MRC#, DATE CHECKED, │
│INFORMATION │CHECKED, │DATE CHECKED, │INITIALS OF CHECKER, │
│ │INITIALS OF │INITIALS OF │PERIODICITY, WORK │
│ │CHECKER, │CHECKER, │CENTER CONDUCTING │
│ │PERIODICITY, │PERIODICITY, │PMS │
│ │WORK CENTER │WORK CENTER │ │
│ │CONDUCTING │CONDUCTING │ │
│ │PMS │SAFETY CHECK │ │
│ STICKER │NONE │RECOMMEND USING │NONE │
│ │ │STICKER ON EQP │ │
│ │ │WITH DETACHABLE │ │
│ │ │CORD. STICKER │ │
│ │ │SHOULD INDICATE │ │
│ │ │SAME INFORMATION │ │
│ │ │AS TAG OR INDICATE │ │
│ │ │"AUTHORIZED FOR USE │ │
│ │ │WITH BATTERIES ONLY"│ │
│MATERIAL │EVEN THOUGH EQUIPMENT MAY HAVE A CURRENT SAFETY TAG, │
│CONDITION │DAMAGE TO THE CORD, PLUG OR CASING INVALIDATES THE │
│ │SAFETY TAG. CHECK FOR SPLICES, EXPOSED CONDUCTORS │
│ │CUTS, TEARS, ABRASIONS, BROKEN EQUIPMENT CASINGS THAT │
│ │EXPOSE INTERNAL COMPONENTS AND POWER CORD MODIFICATIONS. │
1. M-2, M-4 must not skip a calendar month.
A-6 applies to mobile electrical equipment, 2 prong, plastic case.
A-7 applies to mobile electrical equipment, 3 or 4 prong.
S-1R applies to test equipment
M-2 applies to portable electrical tools/devices, 3 prong.
M-4 applies to portable electrical tools/devices, 2 prong, double insulated.
2. Equipment Classifications.
a. PORTABLE ELECTRICAL TOOLS/DEVICES - Equipment that has an attached cord, is hand-held or frequently handled while operated and is plugged into an electrical power source. Examples include drills, grinders, sanders, ventilation blowers, deck buffers, circular saws, deck strippers, drop lights, vacuum cleaners, soldering guns/irons.
b. MOBILE ELECTRICAL EQUIPMENT - Equipment that is not hard-wired, can be moved, but normally is stationary while operating; this includes items fixed in place to prevent movement. Example include adding machines, coffee makers, typewriters, fans, toasters, welding machines, bench grinders, juice dispensers, ships entertainment equipment, televisions, vending machines, refrigerators.
c. STATIONARY/INSTALLED EQUIPMENT - Equipment that is hard-wired into the ships electrical system.
Designated electrical spaces require electrical grade sheet (Type I) throughout the space.
If the compartment is not a designated electrical space, but contains electrical equipment such as switchboards, panels, or electrical insulated work benches, and is not covered with electrical sheet deck covering type I, type II or II matting must be installed adjacent to the electrical equipment or workbenches. The matting should cover an area sufficient to prevent electric shock, but not less than three feet wide. There should be no seams within three feet of an electrical hazard. Exposed corners must be rounded off.
Where to install electrical grade insulating deck coverings:
lOperating areas in the front and rear of propulsion control cubicles, power and lighting switchboards, test switchboards, interior communications switchboards, fire-control switchboards, and shipboard announcing system amplifiers and control panels
lThe area around electronic equipment where personnel who are tuning, operating, or servicing energized equipment may come in contact with a voltage potential
lThe area around workbenches in electrical and electronics shops where electrical or electronic equipments are tested and/or repaired
lThe area around access plates and portable plates
Metal Deck Preparation for Sheeting
Clean the deck surface with stripper and detergents to remove oil, grease, and old finishes. Prime the deck with two to four mils Formula 150. Dry and cure a minimum of sixteen hours. Cement the sheeting to the deck with latex adhesive MIL-A-21016 or the adhesive recommended by the manufacturer. Roll the deck with 150-pound sectional roller.
Tiled Deck Preparation for Sheeting
Install the sheeting over one layer of resilient-type deck system (vinyl, vinyl asbestos, rubber tiles, or sheet). Clean the deck surface with stripper and detergents to remove oil, grease, and old finishes. Cement the sheeting to the deck with latex adhesive MIL-A-21016 or the adhesive recommended by the manufacturer. Roll the deck with 150-pound sectional roller.
Metal Deck Preparation for Matting
Remove old paint, rust, grease, and other contaminants. Coat the deck with two to four
mils of epoxy primer Formula 150 (NSTM Chapter 631 has application instructions). If deck is not coated right after cleaning, wipe it down with degreasing solvent. Place or cement matting over deck. If the matting is not cemented, stencil the outline of the matting on the deck and stencil "ELECTRIC GRADE MAT REQUIRED WITHIN MARKED LINES" inside outline using ¾" or larger letters. Use yellow paint or tape for the outline. If the matting is not cemented and it is installed throughout the space, the outline is not required. Instead, stencil the caution notice on deck so that if any section of the mat is removed, the words will be visible. Round all exposed corners of the matting.
Tiled Deck Preparation for Matting
Remove wax and dirt from the tiles. Abrade the tile surface if using water-base or latex-base adhesive. Use coarse steel wool or fine sandpaper. Place or cement matting over the deck. If the mat is not cemented, stencil the outline of the matting on the deck and stencil "ELECTRIC GRADE MAT REQUIRED WITHIN MARKED LINES" inside the outline using ¾" or larger letters. Use paint or a preprinted self-adhesive plastic film (3M Y-7902) bulls eye. If the matting is not cemented and it is installed throughout the space, outline is not required. Instead, stencil the caution notice on deck so if any section of mat is removed, words will be visible. Round all exposed corners of matting.
Install electrical insulating deck covering so that there are no seams within three feet of an electrical hazard. If this is not possible, take one of the following actions for the matting indicated:
Thermostatic Matting (LONSEAL) - Fuse matting chemically, or heat fuse or weld, using special hot air gun or install a 3-inch or 4-inch wide strip of #51 Scotchtape 20 mil PVC (Poly Vinyl Chloride) tape beneath the seam or install a 1-foot wide strip of electrical grade matting.
Rubber Matting (FLEXIFLOR) - Install a 3-inch or 4-inch wide strip of #51 Scotchtape 20 mil PVC tape beneath seam or install a 1-foot wide strip of electrical grade matting.
The dielectric properties of matting can be impaired or destroyed by oil impregnation, piercing by metal chips, cracking, and dirt. Inspect matting for cleanliness regularly. Inspect matting at least annually for cracks, punctures, and perforations; imbedded metal or conductive particles; and a minimum 1/32-inch thickness (if not cemented to deck). If the matting is defective for any of these reasons, remove and replace it immediately. Ensure that only approved non-conductive wax is used on rubber sheeting/matting.
HAZARDS OF ELECTROMAGNETIC RADIATION
Electromagnetic radiation (EMR) or radio frequency radiation (RFR), between 10 kHz and 300 GHz presents a hazard. EMR can not be seen or easily sensed. It must be measured by the use of special instruments or theoretical calculations. Radiation hazards fall into three categories:
lHazards of Electromagnetic Radiation to Personnel (HERP)
lHazards of Electromagnetic Radiation to Ordnance (HERO)
lHazards of Electromagnetic Radiation to Fuel (HERF)
HAZARDS OF ELECTROMAGNETIC RADIATION TO PERSONNEL
Energy impinging on an object in an electromagnetic field may be reflected or absorbed. Only absorbed energy presents a biological hazard. The amount of energy penetration and its absorption depends on the physical dimensions of the body, electrical properties of body tissues, and wavelength of the electromagnetic energy. When electromagnetic energy is absorbed by body tissues, heat is produced. If the body cannot dissipate this heat as fast as it is produced, internal body temperature rises resulting in tissue damage. If the temperature rise is sufficiently high the person will die. The body's ability to dissipate heat successfully depends on air circulation rate, humidity, air temperature, body
metabolic rate, clothing, power density, amount of energy absorbed, and duration of exposure. The following organs are more susceptible to RF radiation (RFR) than others: lungs, eyes, testicles, gall bladder, and portions of the gastrointestinal tract. Eyes and testicles are the most vulnerable. Electromagnetic radiation can leave someone partially blind or temporarily sterile. The Bureau of Medicine and Surgery established safe exposure limits for personnel who must work in an electromagnetic field. These limits are based on the power density of the radiation beam and time of exposure to the radiation field.
Specific Absorption Rate (SAR)
This is the rate at which non-ionizing RFR is absorbed by the body. The threshold at which adverse biological effects begin is four watts per kilogram of body mass (W/kg). With a safety factor of ten added, the accepted threshold is 0.4 W/kg for the whole body, averaged over any six minute (.1 hour) period. A special limit for "hot spot" or limited body exposure has been set at 8.0 W/kg, averaged over any one gram of body tissue for any six minute period. SAR is important in determining whether a safety hazard exists, but is difficult to measure. It can also be dangerous because it requires actual exposure of body tissue. A related measure that gives an acceptable indication of SAR is the PEL.
Permissible Exposure Limit (PEL)
This is a limit to RFR exposure based on instrumented measurements of the radiation
electric field strength (E) or magnetic field strength (H). Measurements are taken where personnel work or transit. Charts are used to determine if the field strength presents a biological hazard to personnel. PEL readings help determine RADHAZ boundaries.
Permissible Exposure Time (PET)
PET is the maximum time of exposure to a specific power density for which PEL will not be exceeded when the exposure is averaged over any six minute (.1 hour) period. Every effort must be made to protect personnel from harmful exposure to RF radiation, but blanket restrictions do not need to be imposed to achieve optimum safety. Such policy will restrict maintenance that can otherwise be carried out safely, provided certain precautions are taken to keep personnel clear of hazardous areas. Ensure personnel take these precautions:
lVisual inspection of feed horns, open ends of waveguides, and any opening that emits electromagnetic energy will not be made unless the equipment is definitely secured for the purpose of such an inspection.
lEnsure all radar antennas that normally rotate, are rotated continuously, or are trained or elevated to a known safe position while radiating.
lTrain and elevate non-rotating antennas away from inhabited areas, ships, piers, dry docks, and pier cranes while radiating.
lAircraft using high-power radars will be parked (or the antennas oriented) so that beams are directed away from work areas.
lWhere the possibility of accidental exposure might exist, maintenance personnel must have someone stationed topside, within view of the antenna, but well out of the beam. This individual will be in communication with the operator while the antenna is radiating.
lEnsure that radiation hazard warning signs are properly posted and boundary lines are established in accordance with the ship's current RADHAZ certification.
lAll personnel will observe RF hazard warning signs.
If you suspect that a person has been over exposed to EMR, the flow chart duplicated in Figure 2.1-8 helps determine what action must be taken. If the exposure is considered an incident, it must be reported as required by Protection of DOD Personnel From Exposure to Radio Frequency Radiation, DOD Instruction 6055.11.
The following are reportable incidents:
lFor whole body, or partial body exposure of the head/eyes, reporting is required if the exposure is five or more times greater than the PEL for a period exceeding PET.
Figure 2.1-8 Personnel RFR Exposure Chart
│ START │
│WAS ANYONE STATIONED/LOCATED IN THE │NO
│IMMEDIATE VICINITY OF RFR SOURCE? ├──┐
│WAS THE SYSTEM RADIATED WHILE │NO│
│SOMEONE WAS AT/NEAR THE RFR SOURCE ├──┤ ┌───────────────┐
└────────────────┬───────────────────┘ │ │NO OVEREXPOSURE│
│YES ├────┤INCIDENT │
┌────────────────┴─────────────────┐ NO│ └───────────────┘
│WAS PEL EXCEEDED AT THAT LOCATION?├────┤
│WAS PERSON IN AREA │ │
│EXCEEDING PEL LONG │ NO│
│ENOUGH TO EXCEED PET?├───────────┘
│POTENTIAL REPORTABLE │
│INCIDENT (CONDUCT TEST)│
NOTE: At frequencies below 300 MHz, RFR exposure
is considered an exposure to the whole body. Above
300 MHz, RFR exposure can be focused on a limited
area of the body, or caused by an RF leakage source
or a directed beam antenna and resulting in partial
lFor partial exposure of the other areas of the body (except head/eyes), reporting is required when exposure to RFR is 20 or more times greater than the PEL for a period exceeding PET.
The use of HF transmitters at 1kW power and up, antenna congestion, and complicated structures and rigging have increased the possibility of voltages being unintentionally induced on crane hooks, running rigging, booms, ASROC launchers, and parked aircraft. An RF burn hazard exists when there is sufficiently high RF voltage on a metallic object to cause pain, visible skin damage, and involuntary reaction. Resistance of the skin to the current flow at the area of contact causes heat. The effect of this heat ranges from a noticeable warmth to a painful burn. Mild RF burns are usually accompanied by small white spots on the skin. The odor of scorched skin may also be detected. More severe burns, while not necessarily covering a larger area, may
penetrate deeper into the flesh and produce painful, slower healing injuries. Hazardous as it pertains to RF burns is defined as the RF voltage level sufficient to cause pain, visible skin
damage, or an involuntary reaction. The term hazard does not include lower voltages that cause annoyance, a stinging sensation, or mild heating of the skin. The Naval Ships Engineering
Center has prescribed that an open circuit RF voltage exceeding 140 volts on an object in an RF radiation field is hazardous.
RF Burn Reduction Techniques
There are several approaches to eliminate or reduce RF burn hazards:
lHook Insulators - Install insulator links between rigging and boom whip and downhaul hooks.
lNon-metallic materials - Use nonmetallic materials where RF burn hazards are a problem.
lAntenna Relocation - This solution is possible, but seldom practical.
lOperating Procedures - Restrict simultaneous use of certain combinations of antennas, frequencies, and cargo handling equipment. Operate transmitters at reduced power.
When proper precautions are taken, the operation of transmitter equipment with a rated output power no greater than 250 watts, average, (at any frequency) will not cause harm to personnel while handling rigging. However, note that even under these operational limits, electronic transmitting equipment can cause hazardous voltages to be induced in standing rigging and other portions of the ship's structure, particularly those structures and objects (e.g., airplanes and helicopters) that protrude from the ship in the same plane as the radiating source.
RF RADHAZ Signs
When RF burn hazards cannot be eliminated, RF radiation hazard warning signs must be posted. Indiscriminate and excessive use of these signs will reduce their effectiveness. RADHAZ signs are discussed later in this lesson topic.
HAZARDS OF ELECTROMAGNETIC RADIATION TO ORDNANCE (HERO)
The use of Electrically Explosive Devices (EED) for ignition of booster rockets, detonation of warheads, stage separation of multistage rockets, high-speed operation of switches and valves, etc. is increasing. The development of weapons includes a continuous effort to reduce weight and space, lower power requirements, assure positive response, and increase reliability and safety. These are not always complementary goals. The use of EEDs in ordnance systems has become essential; at the same time, the power output and frequency range of radio and radar transmitting equipment have been extended. These transmitters produce high intensity RF fields that can cause premature actuation of EEDs. RF energy can enter ordnance through a hole or crack in its skin or be conducted into it by firing leads, wires, and screwdrivers. Ordnance systems have
proved most susceptible to RF fields during assembly, disassembly, loading, unloading, and handling. The most likely results of premature actuation are propellent ignition and reduction of reliability by dudding. Where out-of-line safety and arming (S&A) devices are used, the actuation of an EED may be undetectable unless the ordnance is taken apart. If there are no S&A devices or if RF energy bypasses the devices, the probability of warhead detonation exists. Three HERO classifications for ordnance have been established:
lHERO Safe - An ordnance item that is sufficiently shielded or protected so that it is immune to adverse effects when used in its expected shipboard RF environment.
lHERO Susceptible - Ordnance that contains EEDs that have been proved by tests to be adversely affected by RF energy to the point that safety and/or reliability is/are in jeopardy when the ordnance is used in RF environments.
lHERO Unsafe - Any electrically initiated ordnance item that becomes unsafe when its internal wiring is physically exposed, tests being conducted on the item require additional electrical connections to be made, electroexplosive devices (EEDs) having exposed wire leads are present, handled, or loaded, the item is being assembled or disassembled, or the item is in a disassembled condition.
Any ordnance containing EEDs, which has not been classified as HERO safe or susceptible by either test or design analysis is classified as HERO unsafe ordnance.
HERO reduction techniques vary depending on susceptibility of the ordnance involved and
frequencies and power density of radiation involved. Ship's personnel can cope with HERO restrictions by reducing power, increasing the distance between ordnance and the transmitting antenna, performing tasks in shielded areas, or securing the transmitter. HERO is not included in
RF RADHAZ certification. HERO surveys of ships are conducted every five years whenever a major change occurs in the emitter suite or ordnance allocation and on the lead ship of a new class. NAVSEASYSCOM sponsored survey teams survey the EME (Electromagnetic Radiation Environment) to determine specific HERO safety measures required for handling, stowage, and transport of ordnance. They will recommend changes to the HERO EMCON Bill, if required. OP3565 provides specific guidance on HERO including safe separation distances from shipboard emitters and aircraft, ordnance HERO classifications and susceptibility consequences, hazardous electromagnetic environs, and situations where restrictions apply.
HAZARDS OF ELECTROMAGNETIC RADIATION TO FUELS (HERF)
Fuel vapors can be ignited by RF induced arcs during fuel handling operations close to high powered radar and radio transmitting antennas. Personnel handling fuels afloat should be aware of this potential hazard. The probability of ignition during normal fueling procedures is reduced by locating transmitting antennas away from fueling stations and vents, using pressurized fueling systems on aircraft, and using JP-5 aircraft fuel. The vapor pressure of JP-5 and DFM (diesel fuel marine or F-76) is low enough that, under normal temperatures, there
is virtually no chance of accidental fires from RF arcs. This limits the area of concern to
automotive gasoline (MOGAS). Under normal operating conditions, volatile mixtures are present only near fuel vents, open fuel inlets, or near fuel spills. Three conditions must occur simultaneously for ignition to occur:
lFor a given ambient temperature, the mixture must contain a specific ratio of fuel vapor to air.
lThere must be enough energy contained in the arc or spark to produce the appropriate temperature for ignition.
lThe gap length of the arc must be long enough to sustain the heat in the arc long enough to initiate the flame.
In the absence of a HERF survey to provide more specific restrictions, when fueling or transferring MOGAS, observe the following precautions:
lSecure all transmitting antennas located within the quadrant of the ship in which fueling is being conducted.
lEnsure RADHAZ cutouts for microwave radiators are not overridden during fueling, which could result in the illumination of fueling areas.
lDo not energize any radar or communications transmitter on either the aircraft or motor vehicle being fueled, or transmitters located on adjacent aircraft or motor vehicles.
lDo not make or break any electrical, static ground wire, or tie down connection, or any metallic connection to the aircraft or motor vehicle, while it is being fueled. Make the connections before fueling commences. Break them afterwards.
RADHAZ certification is conducted by SUPSHIP, shipyards, or test teams as directed by NAVSEA. This certification identifies hazardous areas, establishes PEL boundaries, and
provides guidance for the installation of RADHAZ signs. If a current certification is unavailable, contact the WCAP representative at your local FTSC. RADHAZ certifications are required after installation or major modification of transmitting equipment capable of causing RADHAZ problems, for the lead ship of each class, and as directed by NAVSEASYSCOM. Periodic surveys are conducted to verify compliance with RADHAZ certification requirements.
RADHAZ WARNING SIGNS
DOD standards have been aligned with national and international standards, resulting in a change in the format of RADHAZ safety signs. These signs are now printed on anodized aluminum in two sizes: fourteen inch square and five inch square. The large signs are reserved for shore station use. The small signs may be used either aboard ship or ashore. The following section briefly describes the content and purpose of each sign. RADHAZ signs are depicted in Figure 2.1-9 (page 2-1-39).
Type 1 Warning Radio Frequency Hazard . . . Keep Moving
The Type 1 sign advises personnel not to linger in an area surrounding HF antennas where the RFR permissible exposure limit (PEL) can be exceeded. Although there is no danger from exposure to HF radiations for short periods, personnel shall not remain within an HF antenna PEL boundary (defined by a four inch red line/circle on the deck) longer than three minutes within a six minute period. When required, install Type 1 signs at eye level or where easily seen outside the PEL boundary. Post a sign at each approach to the boundary.
Type 2 Warning Radio Frequency Hazard . . . Beyond This Point
The Type 2 sign warns personnel not to proceed past a designated point before checking established RADHAZ avoidance procedures, e.g. the Personnel Aloft Bill. Deck markings to define exclusion areas are not required or appropriate. Where applicable, Type 2 signs should be installed at eye level at the bottom of vertical ladders or suspended at waist level between the handrails of inclined ladders. When Type 2 signs are used as temporary barriers, such as when weapons direction radars are radiating, they shall be installed at waist level on a nonmetallic rope. This installation of the signs will require that personnel approaching the area take positive action to pass. Type 2 signs shall not be used to limit access to an area that is not subject to RADHAZ, or installed inside a RADHAZ area where personnel have already been exposed to RADHAZ before the sign can be viewed.
Type 3 Warning Radio Frequency Burn Hazard . . . Burn Hazard
The Type 3 sign advises personnel to use special handling procedures when touching metallic
objects which can cause an RF burn, or simply to not touch metallic objects that have proved to be a hazard when illuminated by energy from an HF antenna. Although the hazard may exist only at certain frequencies or power levels, personnel should regard the object as a hazard unless the transmitter is secured. When possible, the RF burn source should be replaced with a nonmetallic substitute or relocated/reoriented to eliminate the hazard before resorting to a Type 3 sign for personnel protection. A Type 3 sign should be installed on the RF burn source or in the immediate vicinity where it can be easily seen. When used on cargo handling running rigging, Type 3 signs must be mounted on the hook insulator and personnel warned not to touch the wire/rigging above the insulator. More than one Type 3 sign should be installed on larger burn sources that can be approached from multiple directions.
Type 4 Warning Radio Frequency Hazard . . . Fueling Operations
The Type 4 sign advises personnel of HERF on ships carrying MOGAS. DFM and JP-5 are not considered a HERF problem and require no special electromagnetic safety precautions during fueling. Most naval ships do not carry gasoline. An exception to this is amphibious ships
carrying gasoline-powered landing vehicles. Install Type 4 warning signs at MOGAS fueling stations.
Type 5 Warning Radio Frequency Hazard . . . Special Condition
The Type 5 sign has a blank area in which special precautions necessary for safe operations can be typed. Its purpose is to advise personnel of procedures to be followed when other RADHAZ warning signs are not appropriate to ensure personnel safety. Examples of appropriate data include:
lInform OOD before placing system in radiate
lIn manual mode, do not depress below horizon between ° and ° relative
lEnsure temporary exclusion barriers are in place before radiating
lDo not stop antenna between ° and ° while radiating
A Type 5 sign is normally installed below decks in a system equipment room. This sign should be installed where it can be viewed easily by system operators while they are positioned for normal operation, in the vicinity of the applicable controls (e.g., radiate or antenna control switch). When mounted on system cabinets or control panels, RADHAZ signs should not obscure switch labels, meters, indicators, or nameplates.
Type 6 Warning Radio Frequency Hazard . . . Hazard to Ordnance
The Type 6 sign advises personnel of a hazard of electromagnetic radiation to ordnance and to
check with command authority. Ordnance is not assembled or disassembled in an RF environment. Items containing EEDs are not stowed in the same compartment or magazine or within five feet of RF cables, waveguides, or other transmitting equipment.
Figure 2.1-9 RADHAZ Warning Signs
All Navy personnel who work with RFR sources or work in an area where the potential may exist for exposure to RFR above PEL must be trained in RFR. This training must be held prior to assignment in an RFR area. Schedule annual refresher training as required to reinforce and reemphasize precautions.
Common shipboard sources of Light Amplification by Stimulated Emission of Radiation (LASER) include laser range finders, laser guided munitions, communications equipment, fiber optics, scoring systems, landing systems, and training aids. Federal safety regulations, including labeling, are applicable to all U.S. Navy lasers except those used for combat or combat training
and those classified in the interest of national security. Hazard assessment of lasers is complex and depends on many factors. Lasers are classified based on output parameters. The classification specifies the relative hazard of the laser and the control measures needed for personnel protection. Laser hazard control programs are necessary to ensure personnel protection. All commands using lasers must have a laser safety program and designate a laser safety officer.
General Laser Safety Precautions
During Laser Designator Operations (LDO) and training, personnel should observe the following safety precautions:
lPersonnel must be required to wear laser safety glasses with the appropriate optical density/characteristics.
lPersonnel should receive special eye examinations as a precautionary measure.
lEach laser munitions range should require strict compliance with special range regulations for laser safety.
lNever try to dismantle laser modules.
lImmediately cease designating if any person comes into the optical sight field of vision.
lDo not designate highly reflective targets like glass or chrome.
lWhen handling the laser designator, always assume it is powered until you have determined otherwise.
lNever point the laser designator at anyone, and ensure that the muzzle is always pointed down range.
lIn training situations, always use eye-safe filters if they are available.
lBinoculars should not be used to view the laser impact area. Binoculars greatly multiply the harmful effects of laser weapons on the eyes.
Laser safety references:
lElectromagnetic Radiation Hazards, OP3565
lNAVOSH Program Manual, OPNAVINST 5100.23
lSafety Precautions for Forces Afloat, OPNAVINST 5100.19
lLaser Safety Technical Manual, E0410-BA-010/7034LASER
PROCEED TO ASSIGNMENT SHEET 2-1-1A IN THE ASSIGNMENT BOOKLET. UPON COMPLETION, TAKE THE ASSIGNMENT BOOKLET TO THE LEARNING CENTER INSTRUCTOR.