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Electrician's Mate 3 - Navy Training Courses

Here is the "Electrician's Mate 3 - Navy Training Courses" (NAVPERS 10548) in its entirety (or will be eventually). It should provide one of the Internet's best resources for people seeking a basic electricity course - complete with examples worked out. See copyright. See Table of Contents.

- U.S. Government Printing Office; 1949

Electrician's Mate 3 - Basic Navy Training Courses - Chapter 17 picture



NOTICE: This page has not bee proofed yet!

Navy electrical equipment is designed and installed with every possible provision for the safety of the men who use it and service it. But this does not completely prevent injury to you and your shipmates or damage to equipment. Safety also depends on the Electrician's l'date. To insure safety while standing watch or working on a circuit, he must always work safely and observe safety precautions. Men have been burned, electrocuted, or maimed for life because they became careless in their work or failed to observe safety precautions.

You were selected to be an Electrician's Mate because of your intelligence, so use your brain to prevent accidents. Injury and damage can be avoided by staying alert, exercising intelligence, and by taking care to work safely. And above all - OBSERVE SAFETY PRECAUTIONS AT ALL TIMES. Violations of safety precautions are the greatest causes of accidents and should be reported and punished as an offense.

Some special safety precautions necessary while standing watch are given in chapter 8; for special precautions necessary while servicing electrical gear see chapter 10; and for precautions in servicing batteries see chapter 13. These and all other precautions necessary while working on electrical equipment aboard ship are summarized in the paragraphs which follow. LEARN YOUR SAFETY PRECAUTIONS NOW. OBSERVE THEM CAREFULLY.



MINOR SCRATCHES and cuts SHOULD always BE GIVEN FIRST AID, as serious infections can result from a small scratch. Get first aid.

Many accidents are caused by skylarking. HORSEPLAY IS DANGEROUS and cannot be tolerated. Good men have been lost. overboard because they would not take the trouble to use a lifeline and wear a lifejacket. WEAR A LIFELINE around your waist, being sure that the other end is secured to the ship, WHENEVER YOU WORK OVER THE SIDE of the ship or on booms, stern light, bow light, in ship's boats, AND ALOFT.

BEFORE GOING ALOFT to work on fighting lights, blinker lights, on yard arms or rigging, first get permission from the OOD and GET RADIO TRANSMITTER SECURED. PULL the FUSES TO CIRCUITS GOING ALOFT, AND TAG SWITCHES OPEN, fastening the tag securely. Have OD's name on the tag and the words, "DANGER-DO NOT CLOSE THIS SWITCH." TIE your TOOLS TO YOUR BELT with a strong cord, BEFORE GOING ALOFT, so they cannot drop on the heads of men standing on deck below you. A better way may be to put all your tools in a bucket which you hoist up and secure aloft with a line.

REQUEST PERMISSION from the OOD BEFORE OPENING CIRCUITS to ship control and navigation circuits. WHEN ALOFT, TEST CIRCUIT WITH your INSTRUMENTS BEFORE TOUCHING it with tools. Many sailors have been killed by a fall when an electric shock knocked them off a mast, yard-arm, or a stage in dry-dock.  


When preparing TO HOIST a heavy motor or other HEAVY MACHINERY, USE a BLOCK AND TACKLE, or a chain fall. Secure the hook well to the overhead, using an I-beam clamp if necessary. Do NOT FASTEN the HOOK TO a CONDENSER, PIPE, or a beam that is not strong enough to support the weight being lifted. Never patch a broken chain with 'wire, a nut and bolt, or other patch. Get it welded properly. WHEN LIFTING, NEVER let a man GET his HANDS OR BODY UNDER THE WEIGHT.


BEFORE A SHIP LEAVES FOR SEA, SECURE all LOOSE MACHINERY, spare parts boxes and other loose objects so they cannot fall, slide or roll adrift as the ship rolls and pitches heavily in a storm or heavy sea. Two hours before ship gets underway, all electrician's mates report to the electric shop and start testing all navigation and ship control circuits. The senior petty officer or chief reports to OOD and to OOW one hour before the ship is to get underway, reporting that all ship control circuits have been tested and are operating properly. SAFETY PRECAUTIONS AROUND SWITCHBOARDS The man on watch must be alert. Listen for strange or unusual sounds and smells. Watch for overloads on the generators. Feel motors and generators to learn if they are overheating. When a man is working on a circuit, he may phone the man on watch on. the switchboard to open a switch for him. Put a tag on the switch, fastening it securely so it cannot fall off the switch. Tags should be kept at switchboard for this purpose, reading "DANGER-DO NOT CLOSE THIS SWITCH." Sign the name and rate of man working on circuit on the tag. Enter this in log book WHEN TWO OR MORE MEN ARE WORKING ON different branches of the SAME CIRCUIT, each should put a tag on the switch, with his name on his tag, and the SWITCH MUST NOT BE CLOSED UNTIL ALL the MEN ARE CLEAR. IN CASE OF DOUBT, take time to CHECK UP and make sure all are clear and it is safe to put power on the circuit, BEFORE CLOSING THE SWITCH. It's better to be safe than sorry.

Figure 156. - Make sure all power is disconnected before working on electrical equipment.

Figure 156. - Make sure all power is disconnected before working on electrical equipment.


Power to switchboards can come in from more than one source of supply. MAKE SURE ALL SOURCES ARE safely DISCONNECTED BEFORE WORKING ON any SWITCHBOARD. Power can come from two or more sources of supply to the shore connection cable, to the distribution and generator switchboard bus bars, the emergency generator switchboard, the steering engine switchboard, and to other vital equipment. Some have automatic transfer switches, others have manual transfer switches which can be operated to put power on the board from an alternate source of electric power. BE SURE that ALL possible SOURCES OF POWER ARE CUT OFF, BEFORE WORKING ON EQUIPMENT.

The EMERGENCY GENERATOR SWITCHBOARD IS ENERGIZED even THOUGH the DIESEL, generator IS NOT RUNNING, because it receives power from the main generators. MEN HAVE BEEN ELECTROCUTED when they touched the emergency generator switchboard bus bars, BECAUSE THEY TOOK IT FOR GRANTED THAT THE EMERGENCY BOARD WAS DEAD WHEN they saw that the DIESEL generator WAS NOT RUNNING. It wasn't, but they are.

In switchboard rooms and other electrical installations, the VENTILATION BLOWERS SHOULD NOT BE AIMED AT or toward the EQUIPMENT. Turn the blower onto the walk. If the blower is trained toward the equipment or switchboard, water from the blower would spray on the equipment and cause a short circuit or possibly electrocute the man on watch.

NEVER GO BEHIND the SWITCHBOARD UNLESS another MAN IS STANDING BY, looking out for you. IF a MAN apparently IS ELECTROCUTED, OPEN SWITCH BEFORE TOUCHING HIM yourself. Use rubber gloves or other insulated protection; then pull him clear quickly, and IMMEDIATELY ADMINISTER ARTIFICIAL RESPIRATION to the victim.

ARTIFICIAL RESPIRATION must be started immediately, the same as to an apparently drowned man, and MUST BE KEPT UP FOR 4 HOURS or until rigor mortis sets in, unless the doctor says there is no further use. Men have been resuscitated by this method several hours after a shock, so do not give up hope.

SAFETY PRECAUTIONS SHOULD BE POSTED in all shops, on switchboards, and in the storage battery charging locker. Take great care to prevent water from getting into switchboards, panels, storage batteries and other electrical equipment, and to keep loose tools from falling on or into them, that can cause a short-circuit and a great deal of damage as well as danger to personnel. Do NOT CARRY METAL tools, rulers, or other metal OBJECTS IN your SHIRT POCKET, as they can fall into machinery or switchboards when you lean over machinery. The resulting short circuit usually severely burns the man involved.



Always WEAR GOGGLES WHILE GRINDING on a tool grinder, while chipping, and while watching others grind' or chip. People who ignored this warning are wearing a glass eye today because they were too lazy to put on goggles.

TAPING the HANDLES of tools with friction tape may give you a better grip on them, but DOES NOT MAKE the TOOL SHOCK-PROOF. They are NOT SAFE to work with ON a HOT CIRCUIT. One hole in the tape, is enough to electrocute or burn a man.

DON'T STICK a BARE screwdriver or other TOOL INTO a HOT FUSE BOX.

WHEN DRILLING a hole, DON'T attempt to HOLD the STOCK IN your HAND-either chuck it in a bed vise, or clamp it with C-clamps, or hold it with vise-grip pliers. GET the RIGHT TOOL FOR the JOB - even if you have to return to shop for it. N ever use a screwdriver to pry with. Use a pry bar or a crow bar. Never use a screwdriver for a chisel, or hammer on it. Never use a wrench for a hammer. NEVER HAMMER on end-bell or other CASTING WITH a BALL PEEN HAMMER. Use a mallet or a hide faced hammer. NEVER LEAVE a SOLDERING IRON PLUGGED IN WHEN NOT IN USE. It will burn up the iron, and may start a fire. Place soldering iron in the rack when not in use.

Return tools to your shop when finished with them, as someone else may be waiting to use them. A good motto for your shop is, "A PLACE FOR EVERYTHING-EVERYTHING IN ITS PLACE."


Storage batteries give off an explosive gas while being charged, and a cigarette, a flame or a spark can cause a disastrous explosion. "No SMOKING" regulations MUST BE ENFORCED strictly WHILE BATTERIES ARE CHARGING .. Always keep connections clean and tight, to prevent arcing that may cause explosion. Never let battery temperature get above 110° F.

Storage batteries use strong chemicals as electrolytes, so TAKE GREAT CARE TO AVOID ELECTROLYTE LEAKING OR SPILLING, TO PREVENT BURKING personnel or damaging equipment.

In mixing electrolyte, use only acid resisting, non-metallic vessel (stone or glass). POUR ACID INTO WATER, NEVER WATER INTO ACID, because explosion may result. Be careful not to spill, to avoid burns.



Rubber gloves will be ruined by heat, sunlight, or pressure. Stow them in a box where temperature will not exceed 90° F.

Figure 157.-  Rubber gloves and leather glove protectors.

Figure 157. -  Rubber gloves and leather glove protectors.


Gloves should not be flattened, folded, or turned inside out. They should be kept free from oil, grease and water. Wash with castile soap in lukewarm water, rinse in cool clear water, before stowing the gloves.

Always wear protectors (leather gloves) over the rubber gloves while working. Before a rubber glove is used, it should be tested for holes. To test, fill glove with air by twirling it with the cuff rolled. It should then be squeezed. If the glove has a hole, air will leak out.



MEN HAVE LOST FINGERS or HANDS, cut off by running machinery BECAUSE SOMEONE CLOSED a SWITCH WITHOUT MAKING SURE IT WAS SAFE TO turn it on and RUN THE MA-CHINE. This is especially dangerous around pumps, blowers, ammunition hoists, elevators, rams, and galley and carpenter shop equipment.

COVERS OR screen GUARDS SHOULD BE INSTALLED TO PROTECT personnel FROM injury or shock from EXPOSED GEARS, CHAINS, AND BARE ELECTRIC CONDUCTORS such as third rails, trolleys, collector rings, brushes, and other electrical installation that is not insulated, or which is mechanically dangerous.


Figure 158. - Test lights.

Figure 158. - Test lights.


Always ASSUME that a CIRCUIT is NOT SAFE UNTIL you are SURE that IT IS DEAD-and MAKE SURE that IT WILL NOT BE ENERGIZED AFTER YOU START WORKING ON IT. USE A VOLTAGE TESTER on circuit. TEST from EACH LEAD to ground, AS WELL AS BETWEEN LEADS. Any man who tests for 440 volts with his fingers will do so but once. Always USE FUSE PULLERS, figure 159, TO CHANGE A FUSE, never fingers, pliers or screwdriver.

ALL METAL connection BOXES, switch boxes, starting boxes, transformer shells, AND motor FRAMES SHOULD BE GROUNDED to the hull or to water pipes, to prevent shock to personnel. This is ESPECIALLY important in PORTABLE drills and other portable ELECTRIC POWER TOOLS, AND SUBMERSIBLE PUMPS.


Fuse puller type 1 - RF Cafe

Fuse puller type 2 - RF Cafe

Fuse puller type 3 - RF Cafe

Figure 159. - Fuse pullers.


Take insulation tests frequently with megger or vibrotester, and test for grounded frame when you test insulation resistance. BE OBSERVANT! Fix or report at once anything you see that is damaged or needs repairing. Replace missing screws, and rotten or missing gaskets, at once. A stitch in time saves nine, in this business.

WHEN USING A PORTABLE electric METER, DON'T connect only one wire and LEAVE other WIRE dangling about LOOSE. Anyone touching it will receive a shock through the meter.

GASOLINE OR BENZINE SHOULD NOT BE USED on or near running machinery, or in an enclosed space, or below decks. INFLAMMABLE VAPORS are invisible, but spread and flow along the deck and down open hatches. They become ignited and SPREAD the FLAME the instant a spark is struck. If necessary TO USE an INFLAMMABLE SOL VENT to clean a motor or parts, first POST a GUARD, ENFORCE SMOKING REGULATIONS, and TAKE CARE that a SPARK IS NOT STRUCK by a tool striking steel.



ALWAYS pull fuses first, or DISCONNECT leads III POWER panel, BEFORE WORKING ON a CIRCUIT. Test a circuit with your neon test light or voltage tester before working on it - always ASSUME that IT IS HOT UNTIL you are SURE. MAKE SURE that IT CANNOT BE ENERGIZED WHILE you are WORKING ON IT.

DON'T THROW POWER ON to a circuit UNTIL you first make SURE that ALL ARE CLEAR. Ask the petty officer or responsible man on that station if motor is free to run, before you start it. This is necessary to prevent injury to men and machinery.

TAKE TIME TO BE CAREFUL! YOUR careful work, observation of safety precautions, and a little thoughtfulness will prevent injury, mutilation or death to your shipmates and to yourself.





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