Overcurrents and Undercurrents
A new book, Overcurrents and Undercurrents - All about GFCIs and AFCIs, has been introduced. It explains how GFCIs - Ground- fault circuit- interrupters, and the latest safety devices, Arc-fault circuit-interrupters, work.
Before these devices, fuses and circuit breakers were are primary electrical system protection devices. The emphasis was on four ways to protect people and the electrical system from the adverse effects of electricity-Isolation, Insulation, Overcurrent Protection, and Grounding.
Grounding and Bonding were required to attempt to insure that any ground- faults through people or electrical system components would become " high level" ground-faults, activating the overcurrent device, and deenergizing the circuit.
"Low level" ground - faults were not protected against until the GFCI was created. It is usually low- level ground- faults which kill people from ventricular fibrillation. Low level faults, regardless of whether they are "ground- faults" cause electrical fires. The GFCI will provide protection from low level GROUND faults, where a residual current condition exists. The AFCI provides fire protection against arc- faults which may not be ground-faults.
The book covers the history of electrical protection, including fuses and circuit breakers, grounding practices in North America and Europe, the effects of current on the human body, related Interntional developments, the evolutionry acceptance through the National Electrical Code, descriptions of the various types of GFCIs and AFCIs, a glimps into the future, term definitions, and World electrical supply systems.
The book, ISBN 0-9674323-1-6, is available from:
Copyright © 2002 Mike Holt Enterprises,Inc.