AFCI devices-tripping on arc-fault - although it may not be an actual arc-fault

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PCBelarge

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Location
Westchester County NY
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Electrical Training and Consulting
Current issues resulting in tripping on arc-faults. Has anyone on this forum been doing research on this or run into the same issues? I have run across this on a jobsite and now am 2 weeks into research and discussions.
I did a presentation this week in NYC for electrical contractors. Not knowing a manufacturer of AFCI devices was in the group. He followed up on my portion of presentation of the issues with AFCI devices. He surprised me with his comments, agreeing with me and telling the Contractors the issue is going to get worse before a fix is resolved.
I had a quick meeting with a construction/electrical attorney today. I am a contractor advocate and I am trying to come up with a temporary resolve until the manufacturers find a resolve. The Attorney is going to help, involving some of his colleagues.
(not sure if this is an okay topic with the moderators???)
 
You can look for all the threads concerning AFCIs but in short, we can't always tell why they trip. The newer models that can flag 'why' should be helping but unfortunately many of us may not have the skills or the equipment to follow up properly. That 'research' on new installations would be done at our own costs. The solution to AFCI is often to replace that older model, that works as designed, with a newer that works as it is designed. Meaning the customer or you, as an EC eats the expense.
 
I have found that arc faults outside the home can also trip them. I have older Square D QO afci’s in my cabin. Multiple breakers would randomly trip, but all within seconds of each other. Turned out, the utility had an arcing connection at the pole mount transformer secondary side. When they fixed that, the breakers quit tripping for a couple of months. Then the tripping started again, same problem again at the pole. Utility changed the connector type, haven’t had a problem since.
 
I installed a new over the range microwave last July and ran a new dedicated 20-amp circuit and put it on a dual function breaker. It has tripped three time. Once shortly after install then again, a month later then 4 months later. Hasn't tripped since fingers crossed.

After the first 2 trips I was going to replace it with a standard breaker or a GFCI but will see.
 
hillbilly1 said:
I have found that arc faults outside the home can also trip them. I have older Square D QO afci’s in my cabin. Multiple breakers would randomly trip, but all within seconds of each other. Turned out, the utility had an arcing connection at the pole mount transformer secondary side. When they fixed that, the breakers quit tripping for a couple of months. Then the tripping started again, same problem again at the pole. Utility changed the connector type, haven’t had a problem since.
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I remember one of the first few new homes I actually installed AFCI's in we were there working, home was nearly finished. This was a rural home and it is not uncommon to occasionally experience a blip in power in rural areas as POCO reclosers get called upon from time to time which is what I assume probably happened in this case as power went off then came right back on. Pretty much every AFCI that happened to be turned on tripped in this event. Probably because of a transient in the supply I would guess. Would a surge protector have stopped them from tripping? IDK.

IIRC this was back when only the bedrooms required AFCI's.
 
I hate AFCIs and have studied the issues with them pretty thoroughly in the field. The vast majority of cases, it is a false trip. Sometimes there is an over-driven staple. Sometimes a ground wire is touching a neutral in a device box. But do you know what is almost never, ever, ever the problem? And actual arcing fault. One instance in 26 years of these things, just one, have I believed it to be an arc fault due to a loose wire but.

The latest thing I dealt with, literally yesterday, was a toaster oven tripping Square D AFCIs. I detailed this in another post. The circuit is good, verified by a Megger. I went so far as to install a brand new circuit solely for the toaster over, to no avail. Other brands of AFCI that I temporarily plugged in don't trip. The Square D algorithm simply doesn't like that toaster. It is a nice new oven with digital controls. I believe that the AFCI is seeing the PWM that the oven is doing to regulate the temperature as an arc fault.

My solution, unpopular with people who take the code as gospel, was to put in a regular breaker after the final inspection. Inspection was Thursday. Yesterday I put in a regular breaker. The solution is to get rid of AFCIs and use GFCI breakers if you want to protect the branch circuit itself. I believe that an arcing fault will develop a ground fault pretty quickly and GFCIs are tried and true at this point.
 
CoolWill said:
I believe that the AFCI is seeing the PWM that the oven is doing to regulate the temperature as an arc fault.
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As I was reading I was wondering if your oven maybe had solid state control of the heating element(s), then you confirmed it. GFCI and AFCI both don't always play well with these things. High frequency switching and high frequency capacitive leakage is the trigger for tripping these things.

Your oven may not have played well with a GFCI either with such a controller in it.
 
One of the area ECs would replace all the AFCIs with standard breakers after inspection. Not good. PP solution.

We found two actual faults over the years. One was a string of old Christmas lights plugged in with broken bulbs. Service was moved more than 6’ so old circuits were protected per code. The other was a rocking chair over the rug covered extension cord.
 
CoolWill said:
I hate AFCIs and have studied the issues with them pretty thoroughly in the field. The vast majority of cases, it is a false trip. Sometimes there is an over-driven staple. Sometimes a ground wire is touching a neutral in a device box. But do you know what is almost never, ever, ever the problem? And actual arcing fault. One instance in 26 years of these things, just one, have I believed it to be an arc fault due to a loose wire but.

The latest thing I dealt with, literally yesterday, was a toaster oven tripping Square D AFCIs. I detailed this in another post. The circuit is good, verified by a Megger. I went so far as to install a brand new circuit solely for the toaster over, to no avail. Other brands of AFCI that I temporarily plugged in don't trip. The Square D algorithm simply doesn't like that toaster. It is a nice new oven with digital controls. I believe that the AFCI is seeing the PWM that the oven is doing to regulate the temperature as an arc fault.

My solution, unpopular with people who take the code as gospel, was to put in a regular breaker after the final inspection. Inspection was Thursday. Yesterday I put in a regular breaker. The solution is to get rid of AFCIs and use GFCI breakers if you want to protect the branch circuit itself. I believe that an arcing fault will develop a ground fault pretty quickly and GFCIs are tried and true at this point.
Click to expand...
I didn’t wire his latest house, but my old boss had me remove all of the afci’s after several months of nuisance tripping’s of multiple breakers. That was eight years ago, and it hasn’t burned down yet. A general contractor we did work for did the same, and that was ten years ago. The only one I wired that had any trip was my cabin, which was the utility problem, and a judge’s house which she refused to give up her very old canister vacuum cleaner, changed the breaker out to the latest version, seemed to fix the problem. (Unless she had her handyman come back and change it) never heard anymore from her.
 
ptonsparky said:
One of the area ECs would replace all the AFCIs with standard breakers after inspection. Not good. PP solution.

We found two actual faults over the years. One was a string of old Christmas lights plugged in with broken bulbs. Service was moved more than 6’ so old circuits were protected per code. The other was a rocking chair over the rug covered extension cord.
Click to expand...
I haven't had any incidents yet that I can confirm was a true arc fault. Once had a melted down receptacle that a space heater was the load that contributed to the melt down. Customer called because it was tripping the AFCI breaker, they also did discover the melted receptacle before calling me.

I thought I maybe was going to have my first actual AFCI tripping case - but discovered the melted receptacle had developed a ground fault and this was likely what the breaker was responding to. Seem to also recall it would trip immediately after turning it on, even with no load, which also screams ground fault to me.
 
kwired said:
As I was reading I was wondering if your oven maybe had solid state control of the heating element(s), then you confirmed it. GFCI and AFCI both don't always play well with these things. High frequency switching and high frequency capacitive leakage is the trigger for tripping these things.

Your oven may not have played well with a GFCI either with such a controller in it.
Click to expand...
It seemed to play fine with the GFCI receptacle it is plugged into now. I remember when GFCIs were prone to that high frequency noise problem. I tripped a whole panel of them in a hospital when I keyed up my old Nextel push-to-talk in 2003-ish🙄

I do believe that much of that has been worked out for GFCIs. I can't recall any recent GFCI nuisance tripping that I didn't travel back to a real fault in wiring or appliance. It's been over 20 years I'm sure since I saw a GFCI trip for no reason.
 
CoolWill said:
It seemed to play fine with the GFCI receptacle it is plugged into now. I remember when GFCIs were prone to that high frequency noise problem. I tripped a whole panel of them in a hospital when I keyed up my old Nextel push-to-talk in 2003-ish🙄

I do believe that much of that has been worked out for GFCIs. I can't recall any recent GFCI nuisance tripping that I didn't travel back to a real fault in wiring or appliance. It's been over 20 years I'm sure since I saw a GFCI trip for no reason.
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GFCI's more recently have been having issues with appliances with electronically speed controlled motors, particularly clothes washers and refrigerators. Too much high frequency capacitive leakage in the motor is generally the culprit.

Though they are normally hard wired and don't require GFCI, I once was going to run a newer gas furnace on a temporary 120 volt pigtail, plugged into temporary construction outlet that of course had GFCI protection. Done that many times in the past when didn't yet have permanent wiring for the furnace but they wanted to get it going right now. Found out that furnaces with variable speed blowers don't play well with GFCI either. Lights and preheats just fine, as soon as it calls for blower to start it trips, every time.
 
kwired said:
I haven't had any incidents yet that I can confirm was a true arc fault. Once had a melted down receptacle that a space heater was the load that contributed to the melt down. Customer called because it was tripping the AFCI breaker, they also did discover the melted receptacle before calling me.

I thought I maybe was going to have my first actual AFCI tripping case - but discovered the melted receptacle had developed a ground fault and this was likely what the breaker was responding to. Seem to also recall it would trip immediately after turning it on, even with no load, which also screams ground fault to me.
Click to expand...
I think removing the ground fault portion of the afci reduced its actual functionality by a great degree. It was the ground fault part that caught the failure, not the arc signature.
 
PCBelarge said:
I am trying to come up with a temporary resolve until the manufacturers find a resolve. The Attorney is going to help, involving some of his colleagues.
Click to expand...
I think its reasonable for a AHJ to want better ground fault / arc fault protection than a regular inverse time breaker offers, as a 15 amp breaker requires 45 amps to flow on the equipment ground to trip it in 2 seconds.
A GFPE breaker will trip at or below 30ma in a similar time, and they are available and cost about the same as a AFCI.
I would simply amend the code and allow a GFPE breaker to be used anywhere a AFCI is required.
 
PCBelarge said:
I did a presentation this week in NYC for electrical contractors. Not knowing a manufacturer of AFCI devices was in the group. He followed up on my portion of presentation of the issues with AFCI devices. He surprised me with his comments, agreeing with me and telling the Contractors the issue is going to get worse before a fix is resolved.
Click to expand...
There's a ten year old Electrical Contractor article that I have linked to in the past when this topic comes up where a spokesman for the manufactures fully admits that they have been using the public for beta testing of AFCI garbage.

We've had forced installation of AFCI for almost twenty years now and the manufacturer's current assessment is it is going to get worse still? My assessment is AFCIs are a fraud unjustly forced onto the public. The only hope is that they get installed in some senator's or high powered attorney's house and a class action suite is filed because of all the nuisance trips.
 
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