Testing personal protective grounds

Abstract

Personal Protective Grounds, Ground Sets or "Ground Chains" are intended to provide protection to the electrical worker by maintaining a sufficiently low voltage across an individual in the event of unexpected line energization. Energization can occur from numerous sources including lightning, falling conductors and operational errors such as closing the wrong switch or breaker. Generally 50 volts is the accepted level (although some organizations may allow 75 volts) that must not be exceeded across the worker and thus the protective ground set during such conditions. In an effort to assure themselves of a ground sets integrity it is becoming common place for companies to test personal protective ground sets. Since many organizations do not have high current test facilities that can be used to test at such elevated currents, low current testing and extrapolation of low current test results may be desirable, especially if numerous ground sets are to be tested. This paper points out that in and of itself low current testing of protective grounds is not a sufficient method to qualify grounds as safe, adequate or good.