How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manfuactured and modular homes

Why are AFCI circuit breakers warm even when no power is being drawn?

Sunday, July 18, 2021

There’s an electronic circuit inside an Arc Fault Circuit Interrupter breaker (both AFCI and CAFCI types) that generates enough heat, even when there is no load on the circuit, to make it 10º to 20º hotter than surrounding regular breakers with no current flow. These breakers will feel warm to the touch when you run your hand down the face of the breakers next to the switches, and that is normal. According to a tech bulletin by Eaton/Cutler-Hammer, "The AFCI contains power electronics which are used to monitor the current and voltage. These electronics give off energy in the form of heat even when there is no load applied to the circuit.”

    The infrared photo at the top of the page shows a cluster of four CAFCI breakers in the left column near the top and one in the right column near the bottom that are 10º F warmer than surrounding breakers. Also, notice that the center of the cluster of breakers is warmer than the edges. 

    The older AFCI breakers (pre-2008) tend to be even warmer in our experience, but if the breaker is downright hot you’ve got a problem. CAFCI and AFCI breakers are recognizable by the test button and label on face of the breaker.

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

What is the difference between GFCI and AFCI circuit breakers? 

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

What is a Dual Function Circuit Interrupter (DFCI)? 

What is the difference between a Combination Arc Fault Circuit Interrupter (CAFCI) and an Arc Fault Circuit Interrupter (AFCI) circuit breaker?  

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

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

When did arc fault circuit interrupter (AFCI) breakers first become required?

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?  

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?

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?  

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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