Engineering controls are devices that isolate the worker from the hazard of exposure. In the realm of electrical safety, engineering controls include such devices as:
- A light switch or outlet cover plate
- A door on a breaker panel
- Covers over terminal posts
- Ground pin on an electric plug (Three-prong plug)
- Ground fault circuit interrupters (GFCI), particularly in damp or wet locations
A GFCI, is a fast-acting circuit breaker designed to shut off electric power in the event of a ground-fault within as little as 1/40 of a second. It works by comparing the amount of current going to and returning from equipment along the circuit conductors. When the amount going differs from the amount returning by approximately 5 milliamperes the GFCI interrupts the current. The arrow in the image on the right points to a GFCI that is incorporated into the receptacle outlet.