Welcome to Module 2

Fundamentals of Electrical Distribution.
If you have successfully completed Module 1, Fundamentals of Electricity, you are prepared to begin learning about electrical distribution systems and the associated equipment. If you have not completed Module 1, Fundamentals of Electricity, we recommend that you complete that module before you begin this one. This module will present a number of different topics, phrases and terms common to the world of electrical distribution. You will be introduced to information that will be used in later modules.

Like the other modules in this series, this one presents small, manageable sections of new material followed by a series of questions about that material. Study the material carefully then answer the questions without referring back to what you've just read. You are the best judge of how well you grasp the material. Review the material as often as you think necessary. The most important thing is establishing a solid foundation to build on as you move from topic to topic and module to module.

Electrical Distribution System

An electrical distribution system is a series of electrical circuits that delivers power in the proper proportion to homes, commercial businesses and industrial facilities. Regardless of the size and applications, the ultimate goal remains universal: the economic and safe delivery of adequate electric power to electrical equipment.

In general, there are three types of distribution systems: Radial Distribution System, Loop Distribution System and Network Distribution System. The type used by the utility company depends on the services required, location and economics.

Radial Distribution System
The Radial Distribution System has one power source for a group of customers. If there is a power failure, the entire group loses power. In addition, a circuit failure somewhere in the system could mean a power interruption for the entire system.

This is the most economical and widely used system. It is used for residential homes where the supply of electricity is not critical if the power is disrupted.

Loop Distribution System
The Loop Distribution System loops through the service area and returns to the point of origin. The strategic placement of switches permits the electric company to supply power to customers from either direction. If one power source fails, switches are opened or closed to obtain power source.

Obviously, the loop system provides better continuity of service than the radial system, with only short interruptions of service during switching. Because the system requires additional equipment for switching, it is more expensive than the radial system. As a result, it is used for commercial buildings and shopping centers where it is necessary to minimize interruptions.