GFCI-AFCI FAQ

What does an AFCI do?
o
An AFCI will shut down, or trip, a branch circuit when certain conditions are met.
AFCIs monitor the circuit for arc faults, an unintentional electrical discharge that
ignite surrounding materials, like wood or insulation. Arc faults are difficult to detect
because they are often intermittent and occur in hidden locations, such as behind
drywall and in the attic.

What does a GCFI do?
o
A GCFI will shut down, or trip a branch circuit when certain conditions are met.
GFCIs protect against electrical shock that result from ground faults. Ground faults
occur when electrical current in devices stray outside of its normal path. GFCIs
analyze the amount of current entering and exiting from the circuit and will trip when
the difference is greater than a certain value.

Where are AFCIs and GFCIs required?
o
States or jurisdictions within the state determine which edition of the National
Electrical Code (NEC) to enforce. Contact your local authorities to inquire about
which edition of the code your local jurisdiction has adopted. As a rule of thumb,
AFCIs are required to be in all dwelling areas, i.e. bedrooms, family rooms, living
rooms, parlors, libraries, dens, sun rooms, recreation rooms, and closets. GFCIs are
required to be in all rooms that water may be present, i.e. bathrooms, kitchens,
laundry rooms, and garages.

Where can arc faults occur?
o
Damaged power supply cords
o
Damaged wiring
o
Pierced wiring
o
Negligence

How can I help prevent an AFCI trip from happening?
o
All connections between light socket and light bulb base should be tight
o
Ensure that the circuit is not overloaded with an excessive amount of electronics
o
Protect electronics on surge protectors
o
All electronics purchased should be Underwriters Laboratories (UL) listed, or
equivalent, and comply with part 15 of the FCC rules
o
Make sure furniture isn’t on or pushing against electrical wires
o
Call an electrician if you discover blackened plugs, very damaged wires, or noisy
circuit breakers

What caused my AFCI to trip?
o

There are four possible causes of an AFCI breaker trip:

Overload (electrical usage would have begun to overheat a circuit’s wires

Short circuit (very high current resulting from fault on circuit)

Ground-fault (small leakage off of the intended circuit)

Arc-fault (sparking happening on the circuit or its lights or appliances)
What do I do if my AFCI trips?
o
Only an electrician should perform the troubleshooting required to fix the problem.
However, the building owner can still find the reason the breaker tripped.
1. Turn the AFCI/GFCI to the “OFF” position (pull handle down)
2. Turn the AFCI “ON” (push handle up)
3. If the breaker is an AFCI, the LED indicators will inform the condition of the
last trip. The figure below displays the trip condition depending on the LEDs
illuminated. The fault stays in the memory of the AFCI for 30 days.

What is the difference between Branch Feeder and Combination Type AFCI?
o
Both branch feeder and combination AFCIs provide conventional thermal and
magnetic overcurrent protection as well as high current or “parallel” arcing fault
detection and fire mitigation for installed wiring and connected cords. The
combination AFCI has the added benefit of enhanced detection of persistent low
current or “series” arcing faults which mitigate fire hazards in cords connected to
outlets.

My AFCI/GFCI is humming……
o
A low humming in the AFCI and GFCI breakers is normal. The humming is due to
the electronics in the breaker and is no cause for concern.

Can I use an AFCI breaker with a GFCI receptacle?
o
Absolutely – this practice will provide arc fault protection as well as protection against
electrical shock.

What is the difference between Equipment Protection (30mA) GFCI and Personal Protection
(5mA) GFCI?
o
The Personal (personnel) Protection GFCI protects personnel, and the Equipment
Protection GFCI is built to protect electrical equipment. The latter has different trip
levels for different types of protection.

What does the Push-to-Test button do on the AFCI/GFCI device?
o
All GFCI and AFCI products are equipped with a Push-to-Test button in order to
check the functionality of the breaker. Pushing the button creates a test fault within
the breaker causing the unit to electrically open the circuit. Pushing the button trips
the AFCI/GFCI device.
Underwriters Laboratories suggests the GFCI and AFCI to be tested monthly.

What are the wiring practices for AFCI
o
Treat the circuit like any other circuit according to the regulations of the local or state
electrical code. Ensure the circuit is clear from any grounded neutrals and doesn’t
share neutrals with any other circuit. If there are shared/grounded neutrals, the AFCI
will trip instantly as soon as a load is applied. Standard thermal magnetic breakers
will not identify wiring errors, such as grounded or shared neutrals, in the system.
The AFCI will trip if there is a wiring error.

Can I use AFCIs/GFCIs with backup or generator power?
o
You can as long as the backup power has reached a steady state of 120 volts prior
to switchover. Overvoltage will cause the AFCI trip. Undervoltage will prevent the
electronics from the AFCI/GFCI to be powered so they will not be able to offer
correct arc fault or ground fault protection. In either case, the thermal magnetic
protection (overcurrent/short circuit protection) will continue to be in place.

Will the AFCI detect a glowing contact?
o
No. AFCIs will identify the symptoms of a glowing contact by detecting a parallel arc.
However, nearby materials may be ignited before the trip occurs.

Why is my AFCI warm even when there is no load on the circuit?
o

Can I use a three wire home run with AFCIs?
o

Yes! An AFCI does not need a ground for proper operation.
Can I use AFCIs with aluminum wiring?
o

Yes, but you must use a two pole AFCI
Can I use AFCIs in an older home with knob and tube wiring?
o

The AFCI contains power electronics used for monitoring purposes that give off heat.
Yes! There are no compatibility issues with using aluminum wiring
Are dimmers compatible with AFCIs?
o
Yes! Power should be kept below 1000 W for dimming loads per UL requirements.
Going above these limits may result in nuisance tripping.