Electrical Wiring – An Introduction

The wire inside a piece of machinery is usually called equipment wire. Wire is measured by its diameter. This measurement is known as the wire gauge. Wire gauge runs in reverse numerical order. In other words, the higher the gauge number, the smaller the wire diameter. Electrical wiring is governed by strict codes. Electrical codes began in the 1880’s at the same time the first extensive wiring was being done. In 1897, the National Fire Protection Association established the National Electric Code (NEC). The National Fire Protection Association was a group of Insurance companies that were concerned about the potential danger inherent in faulty electrical wiring. They had cause for concern. Early wire was bare or covered with cloth. There was little understanding of the need for insulation. The NEC is used in conjunction with local, country, and State codes that strictly control electrical wiring. The codes are concerned with proper size of wire and with insulation. Factors that are considered are the expected load, the frequency of modifications, and the nature of the environment where the wire is used. Homes have small loads, infrequent modifications and a very non-corrosive environment. Commercial establishments are usually in the middle. The load demands are sometimes higher, and modifications are not infrequent. The factory or industrial site has a very high demand. Modifications are frequent, and the environment is often highly unstable. Materials used in wire have varied over the years. Copper has always been the first choice because it is such a good conductor and is very flexible. In the 1960 to 1970’s, aluminum wire became popular due to the rising cost of copper. Insulation was usually rubber although rubber tended to corrode due to exposure to moisture and air. PVC compounds are now used most commonly as wire insulation. Insulation is made in different colors to identify wiring circuits in a system