As a Fireman, you should be familiar with the power and lighting distribution systems, and shore power connections. You will find greater detail on this and other shipboard electrical equipment in chapter 320, Naval Ships' Technical Manual.

POWER DISTRIBUTION SYSTEMS

A power distribution system carries power from the generator switchboards to every part of the ship. This system consists of feeders, mains, submains, load center panels, and distribution boxes. The most important auxiliaries are supplied with normal, alternate, and emergency feeders through automatic bus transfer units, each with a separate source of power. Casualty power systems are installed aboard ship to provide electrical connections when both ship's service and emergency electrical systems are damaged.

LIGHTING DISTRIBUTION SYSTEMS

Lighting distribution systems are necessary to light the ship and to assist personnel in controlling damage. Two lighting systems are installed aboard combatant ships. These are ship's service lighting and emergency lighting. The ship's service lighting normally supplies all lighting fixtures. Emergency lighting circuits are supplied to vital machinery spaces, the radio room, the combat information center, and other vital spaces. The emergency lighting system receives power from the ship's service generators; but if normal power is lost, the emergency system is automatically powered by the emergency generators. Lighting distribution systems are similar to power distribution systems except for the following differences:

1. They are more numerous.

2. They have lower voltages (120 volts). 3. They have smaller panels and cables.

If an emergency power system is not installed, alternate supplies from another ships' service source can provide for services selected according to the basic principles of an emergency lighting system.

SHORE POWER CONNECTIONS

Shore power connections are installed at or near suitable weather deck locations. At these locations, portable cables from the shore, or from a ship alongside, are connected. Power can be supplied through these connections to the switchboard when ship's service generators are not in operation.

ELECTRICAL SAFETY PRECAUTIONS

There are certain safety precautions you should observe when working with or around electrical appliances and equipment. The following are some of the most common electrical safety precautions all shipboard personnel are required to follow:

Do not attempt to maintain or repair electrical equipment yourself. Leave the electrical work to the EMs and IC electricians.

Check personal electrical equipment through the EMs to see if it can be used aboard ship.

Observe and follow all pertinent instructions and electric warning signs aboard ship.

Observe all safety precautions regarding portable electric lights and tools. (Use rubber gloves and goggles.)

Remember, 120-volt electricity is very dangerous, especially aboard ship.

Do not touch or operate any device that has a danger or caution tag attached to it without first contacting the EOOW.

Do not go behind electrical switchboards.

Do not touch bare electric wires or connections; assume all circuits to be ALIVE.

Do not remove steamtight globes from lighting fixtures.

Do not remove battle lanterns from their locations.

Do not use manually operated hand battle lanterns for unauthorized purposes. Each person should have his/her own flashlight.

Do not use electric cable runs to hoist or support any weight.

Do not use the wireways for storage.

Do not permit water to get into electrical equipment.

Remember, a flame, spark, or lighted cigarette can cause a disastrous battery explosion.

Remember, electrolyte from a storage battery can cause severe burns and can damage equipment and clothing.

When you repair equipment that is driven by a motor, have an electrician disconnect the circuit and tag it as out of commission.

Do not start or operate electrical equipment when flammable vapors are present.

Learn the electrical safety precautions applicable to your assigned duties and duty station. By thoroughly understanding electrical safety precautions, you will help prevent injury to yourself and damage to equipment.

If You are ever in doubt about the operating condition of electrical equipment, CALL AN ELECTRICIAN.

SUMMARY

This chapter has introduced you to shipboard electrical equipment and systems. It has given you information about electricity, generators, shipboard power distributions, electric motors, controllers, batteries, port able electrical equipment, shipboard electrical systems and connections, and electrical safety precautions. You should pay particular attention to the safety precautions that have been included within this chapter and in all other chapters. Even though electricity has made our lives easier, it can kill you in an instant if it is not used properly.