AFCI warm and buzzing

[stanley frost]

On this mornings inspection the AFCI breakers were 20 degrees warmer than the other breakers and I could hear a slight buzz. Is this normal? (Everything on the breakers was turned off)

[John Arnold]

Here's a previous post about previous posts about this subject. Hope it helps.

http://www.inspectionnews.net/home_inspection/electrical-systems-home-inspection-commercial-inspection/4824-buzzing-afci.html

[Peter Louis]

simens always, electrician told me fine.

[H.G. Watson, Sr.]

On this mornings inspection the AFCI breakers were 20 degrees warmer than the other breakers and I could hear a slight buzz. Is this normal? (Everything on the breakers was turned off)

The AFCI breakers themselves are always working electricity, as long as the mains are energized and passing electricity to the buss(es) and the AFCI breakers themselves aren't fully cycled (completely) off.

You didn't indicate make of panel/cabinet or the AFCI breakers themselves, classified or otherwise.

"turned off" can be a misnomer - i.e. power supplies (integral or not), caps and/or ballasts and equipment, devices or appliances containing same, low or line voltage dimmers, fan controls, switch devices with indicating lights, etc.

Current Q&A from Siemens regarding both QO and HOM AFCI breakers product information (clickable direct links from siemens square D products web site(s) are provided citation above each quotatiion below) regarding the "warmth" you detect compared to other breakers in the same panel, and "the hum" you may feel or hear coming from same:

from (last updated Dec 2011) AFCI - Arc Fault Circuit Interrupters Frequently Asked Questions (http://www.sea.siemens.com/us//Products/Residential-Electrical/AFCI/Pages/AFCI-FAQ.aspx?rc=1#Could%20an%20AFCI%20feel%20warmer%20 than%20other%20breakers%20in%20the%20same%20panel) ?





Could an AFCI feel warmer than other breakers in the same panel?

An AFCI breaker may feel warmer to the touch than a non-AFCI circuit breaker. This is due to the heat generated from the power supply for the electronics. Siemens AFCI breakers tested in an average ambient temperature of 23 degrees C (73 degrees F) operated at an average temperature of 38 degrees C (100 degrees F). This is well within the UL Standard 489 Section 7.1.4.1.6 which states - Temperature rises on handles, knobs, and other surfaces subject to user contact during normal operation shall not exceed 60 degrees C (140 degrees F) on nonmetallic surfaces. It is warm enough to detect with the hand, but this heat does not impact the operation of the AFCI.


from (last updated Jan 14, 2011) (clickable link): My QO arc fault breakers are humming. Are they OK? | FAQs | Schneider Electric US (http://www.schneider-electric.us/support/index?page=content&country=US&lang=EN&locale=en_US&id=FA110310)




My QO arc fault breakers are humming. Are they OK?

The electronics inside the breaker will produce a low humming noise. Solid state dimmers will make them buzz louder, but this is normal and is no cause for concern.




from (last updated Jan 14, 2011) (clickable link): My Homeline arc fault breakers are humming. Are they OK? | FAQs | Schneider Electric US (http://www.schneider-electric.us/support/index?page=content&country=US&lang=EN&locale=en_US&viewlocale=en_US&id=FA106843)



My Homeline arc fault breakers are humming. Are they OK?

The electronics inside the breaker will produce a low humming noise. This is normal and is no cause for concern.



I believe you will find similar information from most listed or classified combination AFCI circuit breakers in the U.S. market. There may be specific requirements regarding spacing and location, and adjacent placement regarding specific load centers, panels, cabinets, and listed, replacement or classified devices, see specific details from published manufacturer's information/instructions which are in and of themselves part of the listing or classification.



HTH.