Circuit Designation Circuit Name Circuit Designation Circuit Name
Class A-1 Circuits, Continuously Energized
CA Collision alarm system LC Gyrocompass system
EC Low-pressure lubricating oil and high-temperature circulating water alarm system X1LC Auxiliary gyrocompass system
G General alarm system 1MC General announcing system
E Telephone call system 7MC Submarine control announcing system
Class A-2 Circuits, Continuously Energized Underway
GD Diving alarm system XNS Auxiliary stern diving plane angle indicator
K Shaft revolution indicator system EG Engine governor control and tachometer system
1MB and 2MB Motor order telegraph PB Pyrometer indicator.
3MB Engine control indicator system TL Automatic dead reckoning tracer system
N Rudder angle indicator system TP Main ballast indicator system
XNB Auxiliary bow diving plane angle indicator TR Hull opening indicator system
NB Bow diving plane angle indicator Y Underwater log system
NS Stern diving plane angle indicator 1MC General announcing system
7MC Submarine control announcing system
Class A-3 Circuits, Fire Control
6PA Torpedo firing system 17GA1 and GA1 Torpedo data computer
GT Target designation system 17GA3 and 17GA4 Forward and after gyro angle setting regulators
6R Torpedo ready light system
Class A-4 Circuits, Convenience Circuits
A Officers' call bells

Circuits continuously energizedYellow
Underway circuitsBlack
Battle circuitsRed
Utility circuitsWhite
Lighting, Power, and General Utility Cables
SHFLSingle conductor, heat and flame resistant, leaded.
DHFADouble conductor, heat and flame resistant, armored.
SHFASingle conductor, heat and flame resistant, armored.
DCOPDouble conductor, oil resistant, portable.
SHFSSingle conductor, heat and flame resistant, switchboard cable.
FHFAFour conductor, heat and flame resistant, armored.
TCOPTriple conductor, oil resistant, portable.
NOTE: Numbers following the above letters indicate the approximate circular mil area of each conductor with the last three digits omitted.
Interior Communication and Fire Control Cables
MHFAMultiple conductor, heat and flame resistant, armored.
MHFFMultiple conductor, heat and flame resistant, flexible.
NOTE: Numbers following these letters indicate the number of conductors in the cable. Each conductor has a cross-section area of about 2800 circular mils.
Telephone Cables
TTHFATwisted pair, telephone, heat and flame resistant, armored.
NOTE: Numbers following letters indicate number of pairs of conductors.

In general, the designating letters for cable tags on light and power circuits are as follows:

FB-light and power battle feeders

XFE-light and power emergency feeders

The numbers used in connection with the designating letters are indicative of voltage. In other words, the voltage may be determined from the name-tag designation.

Example: 115 to 120-volt circuits are numbered from 100 to 199, and 215 to 250-volt circuits are numbered from 200 to 299.

A circuit designation such as FB-216 indicates that it is a 250-volt circuit because the number is in the range from 200-299.

Voltages of less than 100 volts are indicated in the same general way as above, 40 volts being numbered from 40 to 49, 60 volts from 60 to 69, and so on.

Generator, bus tie, shore connections, main motor, and battery cables use numbers preceded by a zero to distinguish them from the regular feeders, mains, and branches.

Example: A circuit marked FB-0211 would still indicate 250 volts, but it is apparent that it is not a major, or source of supply, cable.

When referring to the marking of lighting and power cables the following terms are used.

A feeder is a cable emanating from a switchboard or from the source of power to the switchboard.

A main is a cable emanating from a feeder.

A submain is a cable emanating from a main.

A branch is a cable emanating from a submain.

A subbranch is a cable emanating from a branch.

When referring to the lighting system only, the following definitions apply:

  A lighting feeder is a circuit emanating from the switchboard and supplying one or more mains.

A lighting main is a circuit feeding from a lighting feeder, supplied through a lighting distribution panel, a feeder junction box, or feeder distribution box.

A lighting submain is a circuit feeding from a lighting main supplied through a distribution box.

A lighting branch is a circuit feeding from a submain and supplying fixtures, lights, fans, and other small equipment.

The same general arrangement applies to power distribution. The following are examples of cable markings:

FB-0210: Lighting feeder, supply to lighting switchboard from source of supply.

F8-102: Lighting feeder from lighting switchboard to distribution boxes on port side.

FB-101: Lighting feeder from lighting switchboard to distribution boxes on starboard side.

18-FB-102: Lighting main connected to feeder FB-102 and supplying after engine room.

18-FB-102-IS: Submain in after engine room, starboard.

FB-0218: Power feeder from main generator to control cubicle.

FB-200: Power feeder from after auxiliary power switchboard to panel in crew's mess room.

1-FB-200: Power main from panel in crew's mess room to galley range control panel.

1-F8-200A: Power submain from galley range control panel to range cooking surface.


(U. S. Bureau of Standards)
Gage No. in A.W.G.Diameter in MilsCross SectionGage No. A.W.G.Diameter in MilsCross Section
Circular MilsSquare InchesCircular MilsSquare Inches
Ampere. The rate of flow of electricity. One volt impressed on a circuit having a- resistance of 1 ohm results in a current flow of 1 ampere.

Coulomb. The unit of quantity of electricity. A current of 1 ampere, for example, is a current flowing at the rate of 1 coulomb per second.

Volt. The electrical unit of pressure that causes the electricity to flow.

Ohm. The electrical unit of resistance. If a pressure of 1 volt is impressed on a circuit and 1 ampere flows, that circuit has a resistance of 1 ohm.

Watt, kilowatt, horsepower. The units of

  electrical power. One horsepower equals 746 watts. For rough estimates, to find horsepower, multiply kilowatts by 1 1/3; to find kilowatts, multiply horsepower by 3/4.

Henry. The unit of inductance. The ability of a circuit to produce an emf by electromagnetic induction when the current in the circuit changes.

Farad. The electrical unit of capacitance. A condenser has a capacitance of 1 farad when a potential difference of 1 volt between the plates of the condenser will store up in it a charge of 1 coulomb. Capacitance is generally expressed in microfarads (one millionth of a farad).

To ConvertMultiply By
Inches to centimeters2.54
Horsepower to watts746
British thermal units to foot pounds778
Kilograms to pounds2.205
Centigrade to Fahrenheit9/5, then add 32
Fahrenheit to centigrade5/9, after subtracting 32


1. Research has shown that at least 75 percent of all accidents is the result of carelessness. Hurrying reduces caution and invites accidents. Remembering the following rules will help to prevent accidents:

Always take time to be careful.

Never take chances.

Turning one's head to engage in conversation while working may result in an accident. The importance of concentration on the job cannot be overemphasized. The purpose of safety rules should be to create a tendency to think and act in terms of safety. A new man is inclined to expose himself, as well as any equipment on which he may be working, to danger because of inexperience; an experienced man is liable to do the same because of overconfidence and habits of work he may have formed. STOP. LOOK. THINK.

2. Men engaged in the following work must wear eye protectors:

a. Acid working

b. Overhead drilling, reaming, etc.

c. Electric and gas welding, cutting, etc.

d. Grinding .

3. Only authorized persons are permitted to work on electrical equipment.

4. When an electrical circuit is to be overhauled or worked on, the main supply switches or cutout switches in each circuit from which power could possibly be fed should be secured in the open position and tagged. The tag should read, "This circuit was ordered opened for repairs and shall not be closed except by direct order of .................................." After the work has been completed, the tag or tags should be removed by the person completing the repairs. In the event that more than one working party is engaged in repair work on an electrical circuit, a tag for each party should be placed on the supply switches.

5. All electrical leads should be considered as live until it is positively proved that they are not. To check a circuit, test the live side with

  the test lamp; then test the dead side with the same lamp and retest the live side. This is to make certain that the test lamp was in good condition.

6. As a general rule use only one hand for switching. Keep the other hand clear. Only one switch should be touched at a time by one per son. Before closing a switch, make certain that:

a. The circuit is ready and all moving parts are free.

b. Men near moving parts are notified that the circuit is to be energized.

c. Proper fuses are installed for protection.

d. The circuit is closed.

Ease the switch to a position for safe quick action and then make the final motion positive and rapid. In opening switches carrying current, the break should be positive and rapid. An exception to this rule is the case of the supply switches to the main generator and main motor field. These are opened slowly to permit the arc to dissipate the stored inductive energy of the coil in order to protect the insulation of the coil.

7. Fuses are safety devices and should be used as such. Fuse pullers made of insulating material should be used for their removal or replacement. Fuses larger than 10-ampere rated capacity should be removed and replaced only after the circuit has been completely deenergized. When a fuse blows, it should be replaced with a fuse of the same rated ampere capacity. Never short out a fuse.

8. Except for operating handles, all parts of circuit breakers normally are conductors. In opening and closing circuit breakers, observe the following precautions:

a. Use only one hand.

b. Keep the hands clear of parts other than the operating handles.

c. Touch only one breaker handle at a time.

d. Where positive and negative breakers have two handles, they should not be closed at one time.


e. Close the breaker first and then close the switches.

f. Trip the circuit breakers before opening the switches.

g. Never disable a circuit breaker.

h. Keep the face turned away while closing circuit breakers.

i. Never stand over a circuit breaker.

9. In so far as is practicable, repair work on energized circuits should not be undertaken. When repair work considered by the commanding officer as essential is undertaken on an energized circuit, it should be accomplished by an electrician's mate under the supervision of an electrician or an experienced engineer officer. In all such work every care should be taken to insulate the person performing the work from ground and to use every known safety precaution. The following precautions must be observed:

a. Provide ample illumination.

b. Remove loose clothing.

c. Insulate worker from ground with dry wood, several layers of dry canvas, or a sheet of phenolic material or sandpaper.

d. Cover working metal tools with insulating rubber tape, not friction tape, as far as is practicable.

e. Insulate live metal parts near the place where work is to be done.

f. If practicable, use only one hand in accomplishing the work.

g. A rubber glove should be used on the hand not used for handling tools. If the work permits, rubber gloves should be worn on both hands.

h. Have men stationed by circuit breakers or switches, and telephones manned if necessary, so that the circuit or switchboard can be deenergized immediately in case of emergency.

i. A man qualified in first aid for electric shock should stand by during the entire period of repair.

  10. Cleaning of energized switchboards, panels, boxes and the like should be limited to removing loose dirt with a painter's duster having no metallic parts and made of soft bristles about 4 inches long.

11. Alcohol should not be used on energized equipment or on equipment that is close to a source of sparks. Alcohol should be exposed in the smallest possible quantity, and should be used only in well-ventilated compartments. Wherever possible, no more than a pint of alcohol should be taken to any one job.

12. Volatile liquids such as insulating varnish, paint, lacquer, turpentine, or kerosene produce inflammable vapors. In working with these liquids ample ventilation should be provided to prevent the accumulation of fumes.

One of the most common and useful cleaning solvents is carbon tetrachloride. This substance must never be used in a confined space and should not be taken to sea in a submarine, as the fumes are toxic and submarine crews have been poisoned by them through leakage of the containers.

13. The risk of accidental contact with live circuits always exists. As a general rule, persons working around live circuits should not approach closer than 1 foot regardless of voltage except to accomplish a particular mission. While accomplishing this mission - STOP, LOOK, THINK.

14. In case of an electrical fire, proceed as follows

a. Deenergize the circuit.

b. Report the casualty to the officer of the deck by messenger or telephone.

c. Secure ventilation.

d. Extinguish the fire.

In extinguishing an electrical fire it should be remembered that quick action is required only in deenergizing the circuit. A CO2 fire extinguisher directed at the base of the flame is always best for electrical fires. Pyrene or carbon tetrachloride is effective in extinguishing an electrical fire that is wholly in the open. But when used in a closed space, it forms a gas, as a result of heat, that causes loss of consciousness. Pyrene


or carbon tetrachloride therefore should never be used in a confined space for fire fighting. Fresh water used intelligently is good for extinguishing a fire. The use of salt water is dangerous. Foam-type fire extinguishers should never be used in fighting electrical fires. In case of cable fires in which the inner layers of insulation, or insulation covered by armor, support combustion, the only positive method of preventing the fire from burning the length of the cable is to cut the cable and separate the ends.

15. Intentionally taking a shock from any voltage is dangerous and is strictly forbidden. Whenever it becomes necessary to check a circuit to see if it is alive, a test lamp, voltmeter, or other suitable indicating device should be used.

16. In the case of live circuits, never implicitly trust insulating material. Insulating material has been known to fail on more than one occasion.

17. If open-type electrical apparatus is in operation when the presence of explosive vapor is detected, the apparatus should be deenergized by means of remotely located switches. The switches should be opened only after it has been ascertained that all persons are clear of the dangerous space.

  18. No person should take loose metal parts or liquids near or above a switchboard or other open electrical apparatus. No person should go above open electrical apparatus without first removing all metal from his pockets. Stowage or insertion of foreign articles in or near switchboards, control appliances, panels, and so forth is forbidden.

19. Covers for all fuse boxes, junction boxes, lever type boxes, and wiring accessories, in general, should habitually be kept closed.

20. In general, cables that are installed where they will be subject to mechanical injury should be protected within such exposed zones by suitable metal casings.

21. Portable cables should be carefully selected and should be of the proper length and cross-sectional area. Spliced portable cables are extremely dangerous and should not be used.

22. The static electrical charge retained by electrical machinery when secured is in certain cases sufficient to cause a severe shock. This should be considered when making connections to an apparently dead machine. Be safe-discharge it to the ground.

1. Treatment for electric shock. A person who has been accidentally shocked by electricity and whose breathing has stopped is not necessarily dead. He may be only stunned or his breathing may have stopped only momentarily. The following instructions should be followed

a. Break the circuit immediately.

b. Separate the victim from the live conductor by a quick motion, using a nonconductor, such as dry rope, a dry coat, or a dry board. The victim's clothes, if dry, may be used to pull him from the live wire. Do not use anything wet or metallic.

c. Beware of touching the heels or soles of the victim's shoes.

d. Do not touch his body with your hands unless they are covered with rubber gloves, dry clothing, or other nonconducting material.

  e. If it is necessary to cut a live wire, use an ax or hatchet with a dry wooden handle, or insulated pliers.

f. If the victim is suffering from burns, use the treatment for burns described in this section.

g. Apply warmth to the victim's body, rub his skin and muscles, and administer stimulants if he can swallow.

2. Resuscitation. As soon as the victim is clear of the conductor, begin administering artificial respiration. The patient's mouth should be cleared of any obstructions such as chewing gum or tobacco, false teeth, or mucus, so that there is no interference with the entrance and escape of air. The patient must be kept warm during artificial respiration and it may be necessary to cover him with blankets and work through them, as well as to apply heat by means


of hot water bottles, hot bricks, and so forth. Be careful not to burn the patient.

There are several accepted methods of applying artificial respiration, but the best and probably the least dangerous is the prone pressure, or Schaefer, method which follows.

3. Artificial respiration, Schaefer method. a. Position. 1) Place the patient on his stomach, one arm extended directly overhead, the other arm bent at the elbow and with the face turned outward and resting on hand or forearm, so that the nose and mouth are free for breathing.

2) Kneel, straddling the patient's thighs.

3) Place the palms of your hands on the small of the victim's back with your fingers resting on his ribs, the little finger just touching his lowest rib, the thumb and fingers in a natural position, and the tips of the fingers just out of sight.

b. First and second movements. 1) With your arms held straight, swing forward slowly, so that the weight of your body is gradually brought to bear upon the patient. The shoulder should be directly over the heel of the hand at the end of the forward swing. Do not bend your elbows. This operation should take about 2 seconds.

2) Now immediately swing backward, so as to remove the pressure completely.

3) After 2 seconds, swing forward again. Repeat, 12 to 15 times a minute, the double movement of compression and release; a complete cycle of respiration in 4 or 5 seconds.

Continue artificial respiration without interruption until natural breathing is restored. Do not become discouraged if your efforts seem to be in vain. Resuscitation often has to be continued a long time before signs of life are apparent. Do not discontinue your efforts until you are absolutely certain that the patient is dead. Sometimes, even after several hours work, resuscitation occurs.

Do not feed the patient any liquids until he is fully conscious.

  When the patient revives, he should be kept lying down to avoid strain on the heart. Give him a stimulant, such as a teaspoonful of aromatic spirits of ammonia in a small glass of water or a hot drink of coffee or tea. Continue to keep the patient warm and at rest.

As a general rule the victim should not be moved until he is breathing normally and then moved only in a lying position. Should it be necessary to move the patient before he is breathing normally, resuscitation should be carried on during the time that he is being moved.

A brief return of natural respiration is not a certain indication for stopping the resuscitation. Not infrequently, the patient, after a temporary recovery, stops breathing again. He must be watched closely, and if natural breathing stops, artificial respiration should be resumed at once.

In carrying on artificial respiration, it may be necessary to change the operator. This change must be made without losing the rhythm of respiration. The relief operator should kneel behind the man giving the artificial respiration, and at the end of the movement, the operator crawls forward while the relief takes his place. By this procedure no confusion results at the time of change of operator, and the established rhythm is maintained.

4. Treatment of burns. Burns result from exposure of the body to dry heat or to strong acids and alkalis, while scalds follow exposure to moist heat, such as hot water or steam. These are serious accidents, attended, at times, with marked shock, and their danger to life depends more upon the extent of the body surface involved, than the degree. The passage of strong electric currents through the body also causes burns.

For convenience, burns are classified as follows:

First degree burns: Reddening of the skin.

Second degree burns: Reddening of the skin with formation of blisters.

Third degree burns: Charring and destruction of the deeper tissues.


There is usually considerable pain with burns and, if the burned area is extensive, marked shock.

Air must be excluded from the burned part. This may be done by means of tannic acid jelly dressings, or by a paste made with water and baking soda, starch, or flour. If the burn was caused by a caustic such as an acid or an alkali, the acid should be neutralized with bicarbonate of soda (ordinary baking soda). If the burn was caused by an alkali, neutralize with a weak solution of acetic acid (ordinary vinegar) before the burned area is covered. Whenever possible, burns should first be treated with tannic acid jelly. If a person is extensively burned, the quickest temporary means of excluding air is to immerse the burned area or the entire body in lukewarm water. Then, having everything in readiness, carefully cut away the clothing, leaving any that may be sticking to the burned skin. The application of tannic acid jelly dressings should follow and the patient put to bed. In case the supply of tannic acid jelly is inadequate, a satisfactory tannic acid solution can be made by pouring one quart of boiling water over 2 1/2 ounces of tea leaves. Allow to steep for at least 15 minutes, then strain. This solution can be applied to the burned area by means of an atomizer or sterile cotton applicators. Several coats of the tannic acid solution are applied while an assistant fans the areas to promote the tanning process. The tannic acid unites with and tans the tissues in the raw areas. When tanning is complete, the burned areas are dark brown in color, and when they have dried they are covered with a hard, leathery crust of a dark brown or black color. Unless infection occurs beneath it, the crust should not be disturbed until it begins to curl up at the edges and to peel off of

  its own accord, when the loosened parts may be cut away with sterile scissors.

The effectiveness of this method of treating burns is seriously interfered with if oils, ointments, or other greasy substances have previously been applied to the burned areas. Any oil, ointment, or grease that is present must be gently but thoroughly removed with a sterile swab and the area sponged with a weak solution of sodium bicarbonate before the tannic acid treatment is begun, even though it may cause considerable suffering.

If tannic acid is not available, an excellent dressing is a solution of ordinary baking soda (2 tablespoonfuls in a pint of boiled water). A salt-solution dressing is also good (a teaspoonful of a common salt in a pint of boiled water). Do not use strong antiseptics on burns. Soaking the injured part in lukewarm water is good and is very often useful to soak off clothing sticking to a burned surface. If blisters have formed and are painful, they may be opened by passing a sterile needle through them and allowing the fluid to escape. Do not destroy the skin raised by a blister. The needle used may be sterilized by burning in a flame. Do not put cotton next to a burn; it sticks and causes trouble. In dressing burns take a pad of sterile gauze, soak in the solution, apply to the affected areas, and hold in place by bandage. In removing the dressings, it is often necessary to soak them off, and warm water or one of the solutions mentioned above may be used for this purpose.

The patient should be allowed to rest and if there is much pain, phenobarbital and aspirin tablets may be given. There may be considerable shock accompanying the burn. A person badly burned should be attended by a physician as soon as possible.


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