12 Oct Ground Fault Circuit Interrupter – GFCI
Ground-Fault Circuit Interrupters (GFCIs)
Electricity can cause severe shock, burns, electrocution, and fire. Construction work presents an increased electrical risk because temporary wiring, extension cords, portable tools, wet conditions, and damaged equipment are frequently present.
A Ground-Fault Circuit Interrupter (GFCI) is a fast-acting protective device designed to reduce the risk of serious electrical shock from ground faults.
How a GFCI Works
A GFCI continuously compares the amount of electrical current flowing to equipment with the amount returning through the circuit. Under normal conditions, these amounts should be essentially equal.
If current begins flowing through an unintended path—such as through a damaged tool, wet surface, or a person’s body—the GFCI detects the imbalance and quickly interrupts the circuit.
GFCIs are designed to trip when the difference in current is approximately 5 milliamperes (mA), helping interrupt potentially dangerous ground-fault current before it causes serious injury.
What a GFCI Does—and Does Not Do
A GFCI provides important protection against ground-fault electrical shock, but it does not eliminate every electrical hazard.
A GFCI:
- Detects current leaking from its intended electrical path.
- Quickly interrupts power when a ground fault is detected.
- Provides additional protection when portable electrical equipment is used in wet, damp, or conductive locations.
- Can reduce the risk of serious or fatal electrical shock.
A GFCI does not protect against all line-to-line or line-to-neutral contact. For example, a person contacting both an energized conductor and neutral conductor may still receive a serious or fatal shock.
Never assume electrical equipment is safe simply because it is GFCI-protected.
GFCIs on Construction Sites
Under OSHA construction requirements, employers generally must provide approved GFCI protection for 120-volt, single-phase, 15- and 20-ampere receptacles that are not part of the permanent wiring of the building or structure and that are used by employees.
This commonly includes receptacles supplying:
- Extension cords.
- Portable electric tools.
- Temporary power equipment.
- Other cord-and-plug-connected equipment.
An extension cord connected to permanent wiring is considered a temporary extension of the receptacle and must receive the required protection.
Extension Cords and Portable Tools
Extension cords receive considerable wear on construction sites. Insulation can be cut, crushed, abraded, or otherwise damaged, creating electrical hazards.
Before use:
- Inspect cords, plugs, connectors, and tools for damage.
- Remove equipment with exposed conductors, damaged insulation, missing grounding pins, or other defects from service.
- Use cords rated for the environment and intended use.
- Protect cords from vehicle traffic, sharp edges, pinch points, heat, and other sources of damage.
- Never modify plugs or remove grounding prongs.
- Keep electrical connections away from water whenever possible.
- Use GFCI protection where required.
Wet and Damp Locations
Water increases the risk of electrical shock because it can provide a conductive path for electrical current.
Use particular caution around:
- Standing water.
- Rain and wet weather.
- Damp floors.
- Wet cord connectors.
- Excavations and trenches.
- Outdoor work areas.
Never handle electrical plugs, connectors, or equipment with wet hands or while standing in water unless the equipment and work practices are specifically designed for those conditions.
Test GFCIs
GFCIs must be maintained in proper working condition. Portable and receptacle-type GFCIs should be tested in accordance with the manufacturer’s instructions.
Where equipped with TEST and RESET buttons:
- Press the TEST button and verify that power is interrupted.
- Press RESET to restore power.
- If the device does not operate correctly, remove it from service and report the problem.
Never bypass, disable, or modify a GFCI.
Assured Equipment Grounding Conductor Program
On construction sites, OSHA permits an Assured Equipment Grounding Conductor Program (AEGCP) as an alternative to GFCI protection for certain receptacles when the program meets OSHA’s specific requirements.
An AEGCP is more than an occasional continuity check. It requires a written program, designated competent persons, required inspections and tests, documentation, and removal of defective equipment from service.
Employees must follow the electrical protection method established by the company for the project.
Remember
A GFCI can save your life, but it is only one part of electrical safety. Inspect electrical tools and cords, keep equipment away from water, use required GFCI protection, and never bypass electrical safety devices.