How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manfuactured and modular homes

What causes an arc fault?

Tuesday, December 17, 2019

An arc fault is any unintentional arcing/sparking in the house wiring, usually by a gap in the wires or their insulation. It can be parallel (hot to neutral or hot to ground) or series (a gap in the hot or neutral wire). Either way, the arcing can can cause burning temperatures that may exceed 10,000º F and can ignite nearby wood framing or other flammable materials. An arc fault can be caused by any of the following defects:

•• Degradation of wire older insulation due to age and heat, especially in an attic.

•• Squirrels or rodents chewing wire insulation, most likely in crawl space or attic.


•• Extension or power cords damaged by sharp bends, running under carpet or behind a bed headboard.

•• Sloppy wiring connection at electrical boxes or appliances.

    An Arc Fault Circuit Interrupter (AFCI) is available as either a circuit breaker or receptacle. It recognizes any arcing in a circuit in a fraction of a second and shuts off power to the circuit to avoid starting a fire. To learn more, go to our blog posts  When did arc fault circuit interrupter (AFCI) breakers first become required? and What is the difference between a Combination Arc Fault Circuit Interrupter (CAFCI) and an Arc Fault Circuit Interrupter (AFCI) circuit breaker?

 • • • • • • • • • • • • • • • • • • • • • • • • • • • 

Here’s links to a collection of our other blog posts about AFCI and GFCI RECEPTACLES AND CIRCUIT BREAKERS:

Does a septic pump or sump pump require a GFCI-receptacle?

What is the difference between what trips a GFCI (ground fault) receptacle and a circuit breaker?

Are Ground Fault Circuit Interrupters (GFCIs) really necessary and worth the trouble? 

What is the code requirement for GFCI protection for receptacles near a wet bar sink?

When was GFCI-protection for kitchen dishwasher receptacle outlet first required? 

Does a washing machine receptacle outlet require GFCI protection?

My spa tub stopped working. What's wrong?  

How do I identify a combination AFCI (CAFCI) circuit breaker? 

What does "listed and labeled" mean for an electrical component? 

What electrical hazards does a Ground Fault Circuit Interrupter (GFCI) NOT protect against?  

What is the difference between GFCI and AFCI circuit breakers? 

Where are GFCI receptacle outlets required?

When were GFCI receptacle outlets first required?

What happens when you press the "TEST" button on a circuit breaker in an electric panel?

What is the difference between the electric service to a mobile home and a site built home? 

Why is there a wall switch next to the furnace or indoor unit of the air conditioner in the garage?

What is a Dual Function Circuit Interrupter (DFCI)? 

How I can tell if a receptacle outlet is tamper resistant?

What is the difference between "grounded" and "grounding" electrical conductors? 

What does it mean when a wire is "overstripped" at a circuit breaker?

Why is there a GFCI breaker in the electric panel for the bathroom shower light and exhaust fan?

What is the switch on the wall with two pushbuttons? 

How far apart should kitchen counter receptacles be spaced?  

How far above a kitchen countertop do electrical outlets have to be? 

How is it possible to provide both GFCI (Ground Fault Circuit Interrupter) and CAFCI (Combination Arc Fault Circuit Interrupter) protection for kitchen and laundry circuits?

My bathroom electric receptacle/outlet is dead and there are no tripped breakers in the electric panel. What's wrong?  

My GFCI reset button is hard to push and won't reset. What's wrong?

Why do some breakers in my electric panel have a "TEST" button on them?

    Visit our AFCI AND GFCI page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.


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