Section V. ELECTRICAL EQUIPMENT

TM 38-260

c. When individual units of plant equipment are shipped to storage as Defense Industrial Reserve (DIR)

equipment, the spare and replacement parts purchased especially for each unit shall be packed and shipped with the

unit. When an individual unit of plant equipment is transferred to another U. S. agency, those spare and replacement

parts purchased for maintenance of that particular unit shall be preserved/packed to level A, C, or to commercial

practice, unless otherwise directed, and shipped with the unit.

d. Spare and replacement parts represent a large investment of Government funds and shall be packed separately

and stored with a package line. In those instances where a production line has been declared excess to the needs of the

Government, disposition of the spare and replacement parts will be at the discretion of the owning agency.

Section V. ELECTRICAL EQUIPMENT

4-20. GENERAL

a. Most items of plant equipment arc dependent upon electrical energy as their main source of power. This energy

is applied by electrical assemblies such as motors, relays, and automatic controls.

b. Copper and aluminum, because of their low resistance to the flow of electrical current, are two of the most

satisfactory elements for use as electrical conductors. For this reason they are found in most electrical assemblies.

Other nonferrous metals such as gold and silver, are also used as conductors. Despite the fact that silver has a lower

resistance than either copper or aluminum, its extreme cost generally limits its use to coatings of copper and aluminum

parts. Care must be taken when cleaning these coated surfaces, as they can be easily damaged or removed by

abrasives used for cleaning purposes.

c. An electrical circuit must be a complete and continuous path between the power supply and the load. For this

reason the circuit must be insulated from any external conductors along its path. As a result, many types of insulating or

nonconducting materials such as rubber, plastic, fabric, and other coatings will be found in electrical assemblies. Since

different cleaning materials may attack these insulating materials, care must be taken to assure that the cleaner and the

insulating materials are compatible.

d. Ferrous metals are used extensively in electric motors. Shafts, housings, laminations, and a number of the

smaller components of electric motors are usually constructed from steel or cast iron. The ferrous parts inside the motor

are generally coated with varnish, which serves to protect them from rust and corrosion.

e. There are too many items of electrical equipment to list them individually in this manual. The preservation and

packing requirements for various items of electrical equipment are contained in military specification MIL-E-17555. If a

particular component is not listed in this specification, the process listed for a similar item should be used.

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