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.
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 before use.
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 each use.
Never use rubber gloves without the leather outer protectors.
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. HigherContinue Reading