A break in the low-resistance grounding path from a tool or electrical system will result in a ground-fault, and electrical current can instead take a path through the user to the ground. This occurrence will result in either severe injuries or death.
A GFCI (ground-fault circuit interrupter) is a rapidly activated circuit breaker that can shut off electric power in 1/40th of a second when there’s a ground fault. It functions by measuring the amount of current traveling to and from equipment along the circuit conductors. If their amounts differ by about five milliamperes, the GFCI will interrupt the current.
A GFCI is designed to trip fast enough for the prevention of electrical incidents. Proper installation and maintenance will ensure that electrical current is cut the instant a faulty tool is plugged in.
Unfortunately, if the grounding conductor is not low-impedance or intact, a GFCI may not trip until a path is provided by the user. Although the user will receive a shock, the GFCI should trip fast enough so that it won’t be harmful.
A GFCI will not offer protection from line contact hazards, such as a person grasping a couple of “hot” wires, holding a neutral and hot wire in each hand, or touching an overhead power line. Nevertheless, there will be protection from a ground fault, the most typical electrical shock hazard. In addition, it will protect against overheating, fires, and damaged wire insulation.
For using power tools away from home or outside, below are three types of GFCIs:
Incorporating a GFCI device within one or more receptacle outlets, the receptacle types are increasingly gaining traction due to their affordability.
Coming in a number of styles, portable type GFCIs are made for ease of transport. Several models can use existing non-GFCI outlets or connect via a cord and plug configuration. Portable types feature a no-voltage release device that will cut power to outlets when a supply conductor is open. Outdoor GFCIs are built with waterproof enclosures to withstand the elements.
An attachment plug featuring the GFCI module, the Cord-Connected Type protects the cord and other equipment attached. It also has test and reset buttons. Similar to the portable type, it also has a no-voltage release device.
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