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wall heaters on AFCI


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Brand new home yesterday.

AFCI's in bedrooms as required, however have never seen fan assisted wall heaters on AFCI before (they had their own AFCI breakers)

Seems they could have nuisance tripping from fan motor?

Anybody seen that before?

I don't know where WA is in terms of AFCI requirements. The NEC, though, requires AFCI protection at all 120-volt, 15- and 20-amp circuits that have outlets in bedrooms (among many other places). A heater is an "outlet" in that it's a location where electricity is supplied to equipment.

So if it's a 120-volt, 15- or 20-amp circuit, it should have AFCI protection. You're not used to seeing it because, I think, 120-volt wall heaters are uncommon and the AFCI requirements are recent.

As for nuisance tripping, I think it's an unwarranted concern. Modern combination type AFCIs (the only kind that should be used now) are smart enough to not trip in response to a fan motor. Also, a fair amount of the nuisance tripping in the early days of AFCIs occured when the AFCIs' GFCI circuit would trip in response to co-mingled neutrals from two or more different circuits. Since the heater circuits are unlikely to co-mingle with anything else, that kind of nuisance tripping is not really an issue in this case.

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A 120 volt fan motor is likely a squirrel-cage type induction motor. Won't set off an AFCI anyway.

On the other hand, plug-in power tools will trip an AFCI because the motors in them are a type of AC/DC motor and have brushes. Brushes generate arcs.

Modern furnace/AC blowers are ECM motors - electronically controlled motors. The currents are switched on/off electronically. I don't know for sure if they will set off an AFCI.

Marc

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Brand new home yesterday.

AFCI's in bedrooms as required, however have never seen fan assisted wall heaters on AFCI before (they had their own AFCI breakers)

Seems they could have nuisance tripping from fan motor?

Anybody seen that before?

I don't know where WA is in terms of AFCI requirements. The NEC, though, requires AFCI protection at all 120-volt, 15- and 20-amp circuits that have outlets in bedrooms (among many other places). A heater is an "outlet" in that it's a location where electricity is supplied to equipment.

So if it's a 120-volt, 15- or 20-amp circuit, it should have AFCI protection. You're not used to seeing it because, I think, 120-volt wall heaters are uncommon and the AFCI requirements are recent.

Makes sense Jim... Yes these were 120 V each, what I normally see is these heaters (paired up) on 240V breakers.

So that lends to this question? Why use 120V with the additional cost of AFCI breakers and would 120v heaters be more economical to operate in this world of high utility costs??...... Jerry

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On the other hand, plug-in power tools will trip an AFCI because the motors in them are a type of AC/DC motor and have brushes. Brushes generate arcs.

Marc

Have outdoor branch circuit that's on an AFCI breaker, and GFCI receptacle. Used small power tools, (drills, weed trimmer,etc) and things worked quite well. Just saying your absolute "will trip" is incorrect.

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On the other hand, plug-in power tools will trip an AFCI because the motors in them are a type of AC/DC motor and have brushes. Brushes generate arcs.

Marc

Have outdoor branch circuit that's on an AFCI breaker, and GFCI receptacle. Used small power tools, (drills, weed trimmer,etc) and things worked quite well. Just saying your absolute "will trip" is incorrect.

Point taken.

Marc

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Have outdoor branch circuit that's on an AFCI breaker, and GFCI receptacle. Used small power tools, (drills, weed trimmer,etc) and things worked quite well. Just saying your absolute "will trip" is incorrect.

think I said:

Seems they could have nuisance tripping from fan motor?

kind of a question not an 'absolute' ?

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A 120 volt fan motor is likely a squirrel-cage type induction motor. Won't set off an AFCI anyway.

On the other hand, plug-in power tools will trip an AFCI because the motors in them are a type of AC/DC motor and have brushes. Brushes generate arcs.

Modern furnace/AC blowers are ECM motors - electronically controlled motors. The currents are switched on/off electronically. I don't know for sure if they will set off an AFCI.

Marc

Marc,

Go buy an AFCI, hook it up and play with it. I think you'll be surprised at how it behaves. Tools, motors, etc that are in good condition and properly wired will not trip it.

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Have outdoor branch circuit that's on an AFCI breaker, and GFCI receptacle. Used small power tools, (drills, weed trimmer,etc) and things worked quite well. Just saying your absolute "will trip" is incorrect.

think I said:

Seems they could have nuisance tripping from fan motor?

kind of a question not an 'absolute' ?

Mr. Lozier, my comment was to Marc's comment (as noted in the quote box.) about small "universal" motor's tripping AFCIs. Anywho, sorry for the confusion. To answer your question, I doubt the wall heater motor (probably a small shaded pole type) will nuisance trip the circuit. AFCI technology has come a long way since their inception. As far as your home inspection is concerned with this issue, I don't believe you have any worries with the wall furnace; it should be fine. Mr. C

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