CHAPTER 1

SAFETY

INTRODUCTION

Successfully completing everyday activities depends on safe execution. Preparation and conduct during these activities reflects on performance. In no other field is this more significant than in the marine field.

Safety is an encompassing subject. This text does not repeat existing electrical safety practices outlined in other references. Instead it emphasizes those standards necessary to successfully complete Army watercraft missions.

Current is the measure of shock intensity. The passage of even a very small current through a vital part of the human body can kill. At about 100 milliamperes (0.1 ampere), the shock is fatal if it lasts for one second or more. Fatalities have resulted from voltages as low as 30 volts.

Conditions on board a vessel add to the chance of receiving an electrical shock. The body is likely to be in contact with the metal structure of the vessel. The body's resistance may be low because of perspiration or damp clothing. Personnel must be aware that electrical shock hazards exist.

Accidentally placing or dropping a metal tool, ruler, flashlight case, or other conducting article across an energized terminal can cause short circuits. The resulting arc and fire, even on relatively low-voltage circuits, may extensively damage equipment and seriously injure personnel.

Touching one conductor of an ungrounded electrical system while the body is in contact with the hull of the ship or other metal equipment enclosures could be fatal.

WARNING

DANGER SIGNALS

Be constantly alert for any signs that might indicate a malfunction of electrical equipment. When any danger signals are noted, report them immediately to the chief engineer or electrical officer. The following are examples of danger signals:

• Fire, smoke, sparks, arcing, or an unusual sound from an electric motor or contactor.

• Frayed and damaged cords or plugs.

• Receptacles, plugs, and cords that feel warm to the touch.

• Slight shocks felt when handling electrical equipment.

• Unusually hot running electric motors and other electrical equipment.

• An odor of burning or overheated insulation.

• Electrical equipment that either fails to operate or operates irregularly.

• Electrical equipment that produces excessive vibrations.

CAUTION

ELECTRIC SHOCK

Electric shock is a jarring, shaking sensation. Usually it feels like receiving a sudden blow. If the voltage and current are sufficiently high, unconsciousness occurs. Electric shock may severely burn the skin. Muscular spasms may cause the hands to clasp the apparatus or wire making it impossible to let go.

For complete coverage of cardiopulmonary resuscitation (CPR) and treatment of burn and shock victims, refer to Ship's Medicine Chest and Medical Aid at Sea from the US Department of Health and Human Services.

The following procedures are recommended for the rescue and care of shock victims:

• Remove the victim from electrical contact at once, but do not endanger yourself. Touching a shock victim who is still in contact with the energized circuit will make you another shock victim. Help the shock victim by de-energizing the affected circuit. Then use a dry stick, rope, belt, coat, blanket, shirt, or any other nonconductor of electricity to drag or push the victim to safety.

• Determine the cardiopulmonary status of the casualty. (Start CPR if spontaneous respiration or circulation is absent.)

• Once the person is stabilized, attend othe physical injuries as they would normally be treated. Lay the victim face up in a prone position. The feet should be about 12 inches higher than the head. Chest or head injuries require the head to be slightly elevated. If there is vomiting or if there are facial injuries that cause bleeding into the throat, place the victim on his stomach with his head turned to one side. The head should be 6 to 12 inches lower than the feet.

• Keep the victim warm. The injured person's body heat must be conserved. Cover the victim with one or more blankets, depending on the weather and the person's exposure to the elements. Avoid artificial means of warming, such as hot water bottles.

• Do not give drugs, food and liquids if medical attention will be available within a short time. If necessary, liquids may be administered. Use small amounts of water, tea, or coffee. Never give alcohol, opiates, and other depressant substances.

• Send for medical personnel (a doctor, if available) at once, but do not under any circumstances leave the victim until medical help arrives.

Observe the following safety precautions when working on electrical equipment:

• When work must be done in the immediate vicinity of electrical equipment, check with the senior engineer responsible for maintaining the equipment to avoid any potential hazards. Stand clear of operating radar and navigational equipment.

• Never work alone. Another person could save your life if you receive an electric shock.

• Work on energized circuits only when absolutely necessary. The power source should be tagged out at the nearest source of electricity for the component being serviced.

• Keep covers for all fuse boxes, junction boxes, switch boxes, and wiring accessories closed. Report any cover that is not closed or that is missing to the senior engineer responsible for its maintenance. Failure to do so may result in injury to personnel or damage to equipment if an accidental contact is made with exposed live circuits.

• Discharge capacitors before working on de-energized equipment. Take special care to discharge capacitors properly. Injury or damage to equipment could result if improper procedures are used.

• When working on energized equipment, stand on a rubber mat to insulate yourself from the steel deck.

• When working on an energized circuit, wear approved electrical insulating rubber gloves. (The rubber gloves used with NBC suits are not acceptable.) Cover as much of your body as practical with an insulating material, such as shirt sleeves. This is especially important when working in a warm space where you may perspire.

• If possible, de-energize equipment before hooking up or removing test equipment.

• When working on energized electrical equipment, work with only one hand inside the equipment. Keep the other hand clear of all conductive materials that may provide a path for current flow.

• Wear safety goggles. Sparks could damage your eyes. The sulfuric acid contained in batteries and the oils in electrical components can cause blindness.

• Ensure that all tools are adequately insulated when working on energized electrical equipment.

• Never work on electrical equipment while wearing rings, watches, identification tags, or other jewelry.

• Never work on electrical equipment while wearing loose-fitting clothing. Be careful of loose sleeves and the battle dress uniform (BDU) shirttails.

• Ensure all rotating and reciprocating parts of the electric motors are adequately protected by guards.

• Remain calm and consider the possible consequences before performing any action.

DAMAGE AND FIRE

Never enter a flooded compartment that has a generator actively producing power. Transfer the load and secure the generator before entering.

Secure power to the affected circuits if there is an electrical fire in a compartment. If critical systems are involved that prevent power from being secured (determined by the chief engineer), extinguish the fire using a nonconducting agent, such as dry chemical, carbon dioxide (C0₂), or halon.

WARNING

Carbon dioxide is the choice for fighting electrical fires. It has a nonconductive extinguishing agent and does not damage equipment. However, the ice that forms on the horn of the extinguisher will conduct electricity.

WARNING

Burning electrical insulation is toxic and can kill in a matter of moments. Use the oxygen breathing apparatus (OBA) when fighting electrical fires. For more information, refer to Marine Fire Prevention, Firefighting and Fire Safety from the Maritime Administration.

PORTABLE AND TEMPORARY ELECTRICAL EQUIPMENT

Ensure all electrical extension cords are approved by either the chief engineer or the electrical officer. Never use an extension cord or power hand tool without it being properly grounded. Regularly inspect all extension cords and portable electrical equipment. Ground all metal multimeters and test equipment to the hull. Some military meters have a grounding jack for this connection.

WARNING

REPAIR SAFETY

Before starting any electrical work, secure the power to the circuit and affix a temporary warning tag to the affected circuit breaker or power source. Check the de-energized circuit with a multimeter. If you must leave the repair and return at a later time, always ensure that the circuit is de-energized before resuming work.

Figure 1-1 shows a temporary warning tag available through the supply system. Any tag can be used as long as it contains the following minimum amount of information:

• Time and date work is started.

• The person performing the work.

• The affected circuits.

• The approval and signature of the chief engineer or electrical officer.

• The required position of the affected switch, breaker, or fuse, such as closed, open, or removed.

When you are engaged in electrical repairs on board a vessel, always work in teams of two or more. Never start working on an electrical system until the chief engineer or electrical officer has been informed. A unit's operational status reflects the vessel's operational status and its ability to get under way. All vessel systems are interrelated. What may appear to be a minor repair may ultimately determine whether or not the vessel is fully operational.

Battery design forces the electrolyte to explode upwards. Never service batteries without proper eye protection. If battery electrolyte gets in your eyes, flush them immediately for 15 minutes and seek medical attention.