Thread: Tester Tripping AFCI's

I've inspected scores of homes equipped with AFCI's, and never had a problem. In the last home however, just plugging my outlet tester into a covered outlet tripped the AFCI. Lamps and everything else work fine, but just plugging in the outlet tester tripped them.

This wasn't the case of a multi-wire or Edison circuit either. There were two AFCI breakers in the panel, and I could trip one or the other, depending on which outlet I tried to test. With a multi-wire circuit, causing either one to trip will also trip the other one, but that wasn't the case here. I'm thinking it might have to do with my outlet tester, which is admittedly getting rather long in the tooth, but it still seems to be working fine - with this anomaly being the exception.

I called another home inspector in our area who has a lot of experience, and he said he'd had the same thing happen about a week prior, and he'd never had it happen before either. I then called an electrician friend to see if AFCI's can start acting up as they get older like GFCI's can, and he said he'd never seen that being the case. It's got us scratching our heads.

I'm hoping that someone on the forum can shed some light on this, and give us a clue as to where the problem might be. Thanks a lot for your help with this!

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Either the device is "bad" or the AFCI is too sensitive or defective.

In new construction, I find approximately 30% of homes have AFCI's that do not properly respond to the Test button, or fail to reset.

Not a week goes by that I don't hear about the nuisance tripping from an AFCI is someone's home.
Invariably, they troubleshoot the problem and the sparky simply swaps out the AFCI breaker for a new one to make the issue go away.

IMHO, these devices aren't ready for prime time.

Dom.

First, curious as to why there are only two AFCI breakers.

Second, the best way to test AFCI breakers is to leave the AFCI breakers on, go around and test all the outlets to make sure they are working, make sure the lights work/ceiling fans, make sure the smoke alarms are on (look for the green light or whatever shows them as being 'on'), then go back and trip the AFCI breakers - now go back around and test all the outlets to make sure they are not working, all the lights/ceiling fans are not working, the smoke alarms are not working.

If the above verifies checks out, that verifies that the AFCI breakers are working as intended.

The test button on the AFCI is really the best test for the AFCI, AFCI 'testers' are basically only 'indicators' because of the various signals the different brands of AFCI are looking for.

As I recall, some AFCI 'testers' have been approved for specific AFCI breakers, but using those AFCI 'testers' on other brands of AFCI breakers may create issues ... and one of those issues may ... may ... may be that the circuity in the AFCI tester triggers the AFCI breaker upon inserting it (although I find that strange as one would think that the AFCI 'tester' is 'off' (the circuitry inside the tester is not connected to the plug) until the 'test' button is pushed, which would turn the tester 'on' ... but maybe inserting the 'tester' is like powering up the circuitry inside the tester and the 'test' button only sends out its signal when pushed.

If the latter is the case, that the AFCI 'tester' is plugged in and 'powers up', then that indeed could trip some AFCIs which are not calibrated to 'not read' that powering up signal.

Just thinking out loud.

Michael,

What kind of tester are you using? I have an INSP-3 and it will periodically trip an AFCI without me pushing the test button. This tester is similar to the Sure-Test, but is manufactured by Amprobe.

It's really frustrating when the AFCI trips like that.

Originally Posted by Jerry Peck

First, curious as to why there are only two AFCI breakers.

Can't answer that one for you. This was a three bedroom home, and the two AFCI breakers were covering all three bedrooms and the hallway outlets.

Originally Posted by Jerry Peck

Second, the best way to test AFCI breakers is to leave the AFCI breakers on, go around and test all the outlets to make sure they are working, make sure the lights work/ceiling fans, make sure the smoke alarms are on (look for the green light or whatever shows them as being 'on'), then go back and trip the AFCI breakers - now go back around and test all the outlets to make sure they are not working, all the lights/ceiling fans are not working, the smoke alarms are not working.

One, I don't test the AFCI's in occupied homes because people too often have computers, televisions, DVR's, etc. plugged in and programmed, or even operating. I do put a note in my report that they weren't tested because of this, and recommending that the buyer test the AFCI's after they've taken possession of the home, and the electronic equipment is no longer in there. Yeah, it's not perfect, but it is a compromise that works best for both parties.

Two, rather than going back around and testing all the outlets, I've found it to be a lot simpler to just check the circuit wire connected to the AFCI with a non-contact voltage detector. It tells me immediately whether or not the voltage to the circuit has been cut by my tripping the AFCI with the on-breaker "Test" button. It also verifies that switching the breaker back on has indeed restored power to the circuit. Otherwise, you'd have to go back around to everything a third time to make sure they're all working again.

Originally Posted by Jerry Peck

As I recall, some AFCI 'testers' have been approved for specific AFCI breakers, but using those AFCI 'testers' on other brands of AFCI breakers may create issues ... and one of those issues may ... may ... may be that the circuity in the AFCI tester triggers the AFCI breaker upon inserting it (although I find that strange as one would think that the AFCI 'tester' is 'off' (the circuitry inside the tester is not connected to the plug) until the 'test' button is pushed, which would turn the tester 'on' ... but maybe inserting the 'tester' is like powering up the circuitry inside the tester and the 'test' button only sends out its signal when pushed.

If the latter is the case, that the AFCI 'tester' is plugged in and 'powers up', then that indeed could trip some AFCIs which are not calibrated to 'not read' that powering up signal.

Just thinking out loud.

I wasn't using an AFCI tester, just a cheap outlet tester from the hardware store.

Originally Posted by Gunnar Alquist

Michael,

What kind of tester are you using? I have an INSP-3 and it will periodically trip an AFCI without me pushing the test button. This tester is similar to the Sure-Test, but is manufactured by Amprobe.

It's really frustrating when the AFCI trips like that.

I was just using a cheap outlet/GFCI tester from the hardware store.

I see this fairly often with older "1st Generation" AFCI's.
The first generation were much more prone to nuisance tripping. I tell my client what I experienced and tell them if it continues to be a problem, have the AFCI breaker replaced with a new one, hopefully a current generation.

Originally Posted by Michael Chambers

Can't answer that one for you. This was a three bedroom home, and the two AFCI breakers were covering all three bedrooms and the hallway outlets.

One, I don't test the AFCI's in occupied homes ...

Understood, which is why I suspected that was a new home and asked about the rest of the outlets.

What edition NEC is in effect for your area? 2002, 2005, 2008?

Two, rather than going back around and testing all the outlets, I've found it to be a lot simpler to just check the circuit wire connected to the AFCI with a non-contact voltage detector. It tells me immediately whether or not the voltage to the circuit has been cut by my tripping the AFCI with the on-breaker "Test" button. It also verifies that switching the breaker back on has indeed restored power to the circuit. Otherwise, you'd have to go back around to everything a third time to make sure they're all working again.

But does nothing to tell you is all the required outlets are AFCI protected, that method only tells you that "something" (and you have no idea which "some things" that is) is on that AFCI breaker.

I wasn't using an AFCI tester, just a cheap outlet tester from the hardware store.

Got it - you would plug a cheap 3-light tester in and it would trip an AFCI ... quite possibly a loose connection in the 3-light tester. Could also be something with the minimal circuitry in the 3-light tester was creating the arc signature that the AFCI looks for.

The only way to check to know which actual outlets are protected is to check everything first (also allows you to make sure receptacles are wired correctly, ceiling fans work, lights work, smoke alarms are on, etc), the trip the AFCI breaker with its test button, then the easy check the second time around is to use a non-contact tester as all you are doing is checking for power (you've already done the wiring check) ... you may be surprised how many outlets which are required to be AFCI protected are not if you were to actually check to make sure they were de-energized when the AFCI was tripped off. That is typically a much bigger issue than many people think it would be.