Feeder Cable Connections
While the electric generator is being installed and
serviced, a part of your crew can connect it to the load.
Essentially, this connection consists of running wire or
cable from the generator to the load. At the load end,
the cable is connected to a distribution terminal. At the
generator end, the cable is connected either to the
output terminals of a main circuit breaker or a load
terminal board. Before the wires are run and
connections are made, it will be up to you to do the
1. Determine the correct size of wire or cable to
2. Decide whether the wire or cable will be buried,
carried overhead on poles, or run in conduit.
3. Check the generator lead connections of the
plant to see that they are arranged for the proper
The information contained in the following
paragraphs will help you in these tasks.
CABLE SELECTION.If the wrong size con-
ductor is used in the load cable, various troubles may
occur. If the conductor is too small to carry the current
demanded by the load, it will heat up and possibly
cause a fire or an open circuit. Even though the con-
ductor is large enough to carry the load current safely,
its length might result in a lumped resistance that
produces an excessive voltage drop. An excessive
voltage drop results in a reduced voltage at the load
end. This voltage drop should not exceed 3 percent for
power loads, 3 percent for lighting loads, or 6 percent
for combined power and lighting loads.
Select a feeder conductor capable of carrying 150
per cent of rated generator amperes to eliminate over-
loading and voltage drop problems. Refer to the
National Electrical Code® tables for conductor
ampacities. These tables are 310-16, 310-17, 310-18,
and 310-19. You also should refer to the notes to
ampacity tables following table 310-19.
CABLE INSTALLATION.The load cable
may be installed overhead or underground. In an
emergency installation, time is the important factor. It
may be necessary to use trees. pilings, 4 by 4s, or other
temporary line supports to complete the installation.
Such measures are temporary; eventually, you will
have to erect poles and string the wire or bury it
underground. If the installation is near an airfield, it
may be necessary to place the wires underground at the
beginning. Wire placed underground should be direct-
burial. rubber-jacketed cable: otherwise, it will not last
Direct burying of cable for permanent installation
calls for a few simple precautions to ensure uninterrupted
service. They are as follows:
1. Dig the trench deep enough so that the cable can
be buried at least 18 inches (24 inches in traffic areas
and under roadways) below the surface of the ground to
prevent disturbance of the cable by frost or subsequent
2. After laying the cable and before backfilling,
cover it with soil free from stones, rocks. and so forth.
That will prevent the cable from being damaged in the
event the surrounding soil is disturbed by flooding or
GENERATING PLANT OPERATIONS
When you are in charge of a generating station,
you will be responsible for scheduling around-the-
clock watches to ensure a continuous and adequate
amount of electrical power. Depending on the number
of operating personnel available, the watches are
evenly divided over the 24-hour period. A common
practice is to schedule 6-hour watches, or they may be
stretched to 8-hour watches without working undue
hardship on the part of the crew members. Watches
exceeding 8 hours, however, should be avoided unless
emergency conditions dictate their use.
The duties assigned to the personnel on generator
watches can be grouped into three main categories: (1)
operating the equipment, (2) maintaining the
equipment, and (3) keeping the daily operating log.
Operating and maintaining the generating equipment
will be covered in the succeeding sections of this
chapter, so for the present you can concentrate on the
importance of the third duty of the station
operatorkeeping a daily operating log.
The number of operating hours are recorded in the
generating station log. The log serves as a basis for
determining when a particular piece of electrical
equipment is ready for inspection and maintenance.
The station log can be used in conjunction with
previous logs to spot gradual changes in equipment
condition that ordinarily are difficult to detect in day-
to-day operation. It is particularly important that you
impress upon your watch standers the necessity for
taking accurate readings at periods specified by local