A power distribution system includes all parts of an
electrical system between the power source and the
customers service entrance. It includes the use of
overhead and underground transmission methods and
the equipment required for the control and protection of
the system and personal. The power source may be
either a local generating plant or a high-voltage
transmission line feeding a substation that reduces the
high voltage to a voltage suitable for local distribution.
At most advanced bases the source of power will be
generators connected directly to the load.
This chapter will be mainly concerned with the
overhead distribution system. Generally speaking, an
overhead distribution system can usually be installed
and maintained more efficiently than an underground
system. Also, for equivalent conductor size, an
overhead system has higher current capacity and offers
greater flexibility with regard to changes.
In this chapter you will learn about line work safety,
pole climbing, and the tools and equipment a lineman
uses. You will learn the basics in constructing and
maintaining a power distribution system as well as the
component parts of the system.
SAFETY IN POWER
The topic of safety that is covered in this chapter is
the most important. The potential for an accident is
constantly present during construction and
maintenance operations but is much greater when crew
members are working on power distribution systems.
The presence of HIGH VOLTAGE in your work
area increases your need for heightened awareness of
the potential for serious injury or death that may be
caused by carelessness and the necessity to take
precautions to ensure the safety of all personnel.
Cranes, earth augers, bucket trucks, and line trucks
with booms that are capable of contacting HIGH-
VOLTAGE lines because of their height capabilities
must be operated with caution. A minimum separation
of 10 feet must be maintained between the equipment
and the energized power circuits at all times. The
equipment must be maintained in first-class mechanical
condition. SAFETY FIRST must be the primary goal.
To ensure the SAFETY of all personnel working on
power distribution lines, you should observe the
following safety precautions:
Ensure that all hot-line equipment is routinely
tested according to the manufacturers specifications
Ensure that all hot-line equipment, including
rubber gloves, is stored in appropriate containers to
provide the required physical protection.
Perform air leak tests on rubber gloves before
Never use rubber gloves without the leather
Ensure that the hard hats of crew members are
rated to withstand 20,000 Vac and that no metal devices
are or have been attached to them.
All members of the line crew must be trained in
the application of the first-aid techniques required to
treat victims of electrical shock.
Ensure that no individual is ever allowed to work
alone or near circuits or devices conducting electrical
energy over 30 Vac.
Tag and lock out all circuits that are de-energized
to perform work.
Install ground sets between the electrical source
and your work on all de-energized circuits when the
disconnecting means is not in sight or when the
potential for contact between the de-energized circuit
and an energized circuit is present.
Maintain a minimum of 3-foot clearance
between personnel and any live power circuit or device
conducting between 600 and 20,000 Vac. Higher