Introduction
Ground Fault Circuit Interrupters (GFCIs) are essential safety devices that protect people from electrical shocks by quickly detecting and interrupting dangerous ground faults. Whether in homes, workplaces, or construction sites, GFCIs play a crucial role in preventing electrical hazards, especially in wet or damp environments.
Ground Fault Circuit Interrupters
Here is an overview of essential information about GFCIs:
- GFCIs protect against electric shock
- It is a fast-acting circuit breaker
- If a surge in power is detected, it “trips” the circuit, meaning it disconnects the power through the circuit until it is reset
- The GFCI will trip if the difference is more than 5 milliamps
- And, when a GFCI trips, it shuts off the electricity in 1/40 of a second
The GFCI will not protect you from line-to-line contact hazards, such as holding two “hot” wires or a hot and neutral wire in each hand.
Note: mA – Milliampere, or milliamp: 1/1000 of an Ampere. Ampere is the basic unit for measuring electrical current.
GFCIs should be used when operating electric tools and extension cords, or when using 120-volt, single-phase, 15-20A outlets that are not part of the building’s or structure’s permanent wiring.
Injuries Due to Current
Injuries resulting from electrical current can vary in severity, including:
- 3 mA will cause a painful shock; your reaction to the shock may cause further injury to you or others around you
- 5 to 10 mA is the range of current it takes to create the “No-Let-Go” type of muscle contractions (The “let-go” current threshold is defined as the maximum current at which a person is still capable of letting go of the source)
- 30 mA can cause temporary lung paralysis
- 50 mA can cause possible ventricular fibrillation (heart dysfunction)
- And, 100 mA to 4A can cause heart failure; if not rescued immediately, death will occur rapidly
Safety Precautions
When using GFCI’s, it is important to adhere to safety precautions, such as:
- Be sure that all temporary wiring is installed and completed with GFCI protection
- Never tamper with or bypass the GFCI unit
- To minimize nuisance tripping (tripping due to damp conditions) keep cords away from water
- Place the GFCI as close to the power source as possible
- Always use a GFCI when using plug and cord equipment, especially extension cords
- Always plug the GFCI in at the source of the electricity
- And, if you find a GFCI that does not work or has physical damage, do not use it and remove it from service
Note: Surge Protectors are NOT GFCIs and must not be used on construction sites.
Inspection
When inspecting GFCIs:
- Look for external defects such as deformed or missing pins, insulation damage, and indications of internal damage
- Visually inspect cord sets, cap, plug, and receptacle of cord sets
- And, remove damaged or defective equipment until repaired
Only a competent person should inspect GFCIs. Inspections shall be documented, even portable GFCIs. Additional inspection is required when an outlet is returned to service following repair and after any incident which can be suspected to have caused damage.
Testing GFCIs
Testing Ground Fault Circuit Interrupters (GFCIs) is essential to ensure they are functioning properly and providing the necessary protection. Regular testing helps prevent potential electrical hazards and ensures safety in various environments. GFCIs must be tested by a competent person before each day’s use. The GFCI must always be tested before use by:
- Plugging it in
- Pushing the test button
- And, pushing the reset button
If the GFCI will not test or retest, remove it from service immediately.
A competent person should conduct monthly tests and visual inspections. Testing records must be kept.
Resources
OSHA has a Oregon OSHA Fact Sheet for GFCIs.
OSHA also provides a webpage that discusses the different types of GFCIs.
Conclusion
Ground Fault Circuit Interrupters (GFCIs) are a vital safety feature that helps protect against electrical shocks, especially in environments where moisture is present. Regular testing and proper installation of GFCIs can significantly reduce the risk of electrical hazards, ensuring a safer environment for both residential and commercial spaces.