GFCI

Ground Fault Circuit Interrupter (GFCI)

A Ground Fault Circuit Interrupter (GFCI) is a device designed to protect people from electric shock by interrupting a household circuit when there is a difference in the currents in the hot and neutral wires. This difference indicates a leakage current, which could be flowing through a person who is grounded and accidentally touching the energized part of the circuit. GFCIs are crucial safety devices in both residential and commercial electrical systems.

Functionality

GFCIs work by monitoring the amount of current flowing from hot to neutral. If there is any imbalance, it trips the circuit. The GFCI can detect differences as small as 4 to 5 milliamperes and can react as quickly as one-thirtieth of a second, which is fast enough to prevent a lethal shock.

Types of GFCIs

There are several types of GFCIs used in different applications:

• Receptacle GFCI: This is the most common type and is installed in place of a standard electrical outlet. It protects against ground faults for devices plugged into the outlet.
• Circuit Breaker GFCI: Installed in a panelboard, this type protects an entire circuit and all devices connected to it.
• Portable GFCI: Used for temporary protection, these devices can be plugged into a standard outlet and then provide GFCI protection to devices plugged into them.

Installation and Testing

GFCIs should be installed in areas where electrical circuits may come into contact with water, such as bathrooms, kitchens, garages, and outdoor locations. The National Electrical Code (NEC) requires GFCI protection in these areas to reduce the risk of electric shock.

To ensure proper functionality, GFCIs should be tested monthly. This can be done by pressing the "Test" button on the device, which should cause the "Reset" button to pop out, cutting off power to the outlet. Pressing the "Reset" button should restore power.

History

The concept of ground fault protection was developed in the 1960s. The first GFCI was patented in 1965 by Charles Dalziel, a professor of electrical engineering at the University of California, Berkeley. The introduction of GFCIs has significantly reduced the number of electrocutions and electrical injuries in homes and workplaces.

Regulations and Standards

GFCIs are mandated by the National Electrical Code (NEC) in the United States and similar standards in other countries. The NEC has progressively expanded the requirements for GFCI protection since their introduction, reflecting their importance in electrical safety.

Also see

• Circuit breaker
• Electrical safety
• National Electrical Code
• Residual-current device