AFCI breaker - furnace motor keeps tripping it

[kwired]

The only way I see AFCI required is if the furnace is sitting in the middle of a room or area that meets 210.12(A) Dwelling Units details. Hopefully it is on its own BC.

If other codes were followed a gas furnace would need to be separated from those spaces I believe, not sure of finish rating required, probably at least 30 minute in one family dwellings though, so it probably should be in a room that is not also a habitable room and with sheet rocked walls/ceiling which should relieve you from AFCI requirements applying to it - so far anyway.

 

[kwired]

I have to ask OP if this furnace has a ECM blower motor? Those don't seem to play well with AFCIs or GFCIs.

Some ignitors on gas appliances also don't seem to play well with them.

 

[ammklq143]

My home has a natural gas furnace in the daylight basement. The room the furnace is in, is not a bedroom or otherwise occupied. We store items in the room (at least six feet away from the furnace).

The home was built in 2018. We had some electrical work done this year (2022). For that inspection, we happened to get the same State of WA L&I electrical inspector for our work, as who originally inspected the home in 2018.

According to him, some of the AFCI breakers were switched out for standard breakers namely, the furnace circuit breaker. I happen to know the original homeowner (who is a close family member to me), and he said "yes, we changed them out as they kept tripping. My wife's mixer in the kitchen would trip...even the brand new furnace would trip the AFCI, so I changed them to standard breakers".

Long story short...I had an AFCI breaker put in for the furnace at the main panel. And now...every few days, if not more often...the AFCI breaker trips.

The inspector won't pass my new electrical work until he sees an AFCI on my furnace circuit breaker, which I would have thought was grandfathered...but he says it was swapped since he inspected in 2018. (and he is correct)

I'm at a loss of what to do. I suppose I can have him inspect with the AFCI, and then change the breaker back to standard...like the prior homeowner??

Any thoughts, would be appreciated.

The kitchen receptacles would need to be arc fault and ground fault protected, but I've never seen a furnace on an arc fault or ground fault. I would simply ask for the code that states it needs arc fault protection. It could be a local code but I've never heard of such a thing.

 

[kwired]

The kitchen receptacles would need to be arc fault and ground fault protected, but I've never seen a furnace on an arc fault or ground fault. I would simply ask for the code that states it needs arc fault protection. It could be a local code but I've never heard of such a thing.

If the furnace is 120 volts and in any the locations mentioned in 210.12 it would require AFCI protection.

Most time furnace is not in any those rooms though, and other building codes often require it to be in separate room with a particular finish rating as well, so this makes it unlikely to need AFCI because of the room it is located in.