Grounds,grounds,and more grounds

Abstract

This paper discusses the need for proper grounding of electrical equipment from the standpoint of safe ty and performance. Seventeen diagrams are em ployed to illustrate the most important points.

The discussion follows a fundamental vein in illus trating the proper connections of electrical apparatus to specifically avoid difficulties from common im pedances and "ground loops."

Some of the many so-called grounds that are en countered in instrumentation are illustrated and defined according to function, in an attempt to clar ify what appears to be a somewhat confusing array of grounds. A computer grounding system is illus trated, as is a so-called hub ground method of in tegrating several computers (or other devices) into a compatible system.

Emphasis is placed on the interconnection of elec trical devices, and attention is called to the need for thought concerning the circuit(s) formed by the casual treatment that is often given to such appar ently simple things as ground connections.

This paper was written to provide information for operators who do not have specific electrical back grounds, and as a reminder to the electrical prac titioner that the most important connection of all is frequently the one called ground.

"Ground," with its many connotations and impli cations, seems to raise some degree of confusion whenever it appears. There are grounds and grounds and grounds such as: signal ground, shield ground, power ground, relay ground, etc. This paper will at tempt to clarify this situation by examining the case from the ground up (wherever that is).