Surprised that the ark fault breaker didn?t trip

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david

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I did a final inspection fir a dental office. I removed a panel cover and found the neutral in the panel not landed along with a red conductor. The red conductor because they ran out of 12/2 and the red conductor wasn't used at all. At first I didn?t think much of it. I already asked if any multi-wire circuits where run for any of the branch circuits and was told no.

Then I asked what is this neutral for did you run any spare circuits. The answer was no spare circuits.
And the electrician also stated everything is working.

As most of you already figured out if the circuit is working and the neutral is not landed then something is wrong. The electrician then landed the neutral for the circuit then got a little ticked when I said you need to trouble shoot that circuit he said why everything is working.

I asked if he had an amp meter and I had them run a small shop vac. On the circuit 2.4 amps on the ungrounded and .4 amps on the grounded conductor. He was still agitated so I ask if he had a spare ark fault breaker in his van he said yes, and used it for a test on the circuit to my surprise the circuit held. I then said it may have been a poor choice on my part to suggest an ark fault breaker for this test I then suggested a GFCI circuit breaker when the GFCI opened the circuit I was then able to convince him it was important enough to trouble shoot the circuit. It turned out that an equipment ground was pushed up against a neutral in one of the hall rec. outlets.
 
GoldDigger said:
Your test arc fault breaker may have been one that did not include a GF component.
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I thought about that after the fact and the equipment ground may have been pushed up tight to the neutral not creating any ark when the circuit was under load.
I just had Ark faults trip so fast in the past when touching the neutral an equipment grounds I was just surprised in this case one held.

You know I never would have investigated the circuit had the neutral been landed when I opened the panel and that was one of the comments the electrician made when he was ticked off. I wonder now how many circuits are amped when there is no indication of something wrong. I also wonder about the rest of the circuits in this building now.
 
A circuit analyzer (not just the go/no go plug in tester with lights) will detect a ground to neutral short from the far end if it is close enough to the receptacle.
 
GoldDigger said:
A circuit analyzer (not just the go/no go plug in tester with lights) will detect a ground to neutral short from the far end if it is close enough to the receptacle.
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HUH, It will show a close but not touching connection.
 
This all coming from memory here -neutral to ground fault will not necessarily have enough current flow to cause trip. I believe GFCI standards though do require circuitry that injects a signal in the neutral that does result in immediate trip if it faults to ground whether there is normal circuit current flow or not. AFCI with GF component don't necessarily have this feature included, and may actually need normal circuit current flow before significant current can leak to ground (probably at least 30mA) to cause the GF component to respond.
 
kwired said:
This all coming from memory here -neutral to ground fault will not necessarily have enough current flow to cause trip. I believe GFCI standards though do require circuitry that injects a signal in the neutral that does result in immediate trip if it faults to ground whether there is normal circuit current flow or not. AFCI with GF component don't necessarily have this feature included, and may actually need normal circuit current flow before significant current can leak to ground (probably at least 30mA) to cause the GF component to respond.
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OP said 2.4 amps ungrounded and .4 amps grounded. That means that 2 amps would have been on the grounding conductor, right?
 
K8MHZ said:
OP said 2.4 amps ungrounded and .4 amps grounded. That means that 2 amps would have been on the grounding conductor, right?
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That is how i would understand it.

hurk27 said:
Or a different neutral path back to source if all the neutrals in a junction box got made up as one neutral:happyyes:
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I also thought of that but the electrician insist that there is only one neutral in any junction point, he said that all the splices are in the device boxes for the recs. and there is only one circuit involved
 
They only other thought that I had was I noticed some white paint from over spray that was on the Ark Fault breaker that was brought from his van. I dismissed it though because I reasoned that he wouldn?t knowingly use a breaker that he knew to be faulty, but I guess that is a possibility that the ark fault breaker just was damaged and not working correctly.
 
david said:
They only other thought that I had was I noticed some white paint from over spray that was on the Ark Fault breaker that was brought from his van. I dismissed it though because I reasoned that he wouldn?t knowingly use a breaker that he knew to be faulty, but I guess that is a possibility that the ark fault breaker just was damaged and not working correctly.
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Arc
Just sayin............:)
 
Does AFCI's with no GF component have a neutral termination, or at least a load side neutral termination? Never seen one so I don't know and the GE's are the only ones I am aware of that exist. If so, it still likely doesn't care about current imbalance as that is what GF protection is all about, AFCI is not the same thing.
 
kwired said:
Does AFCI's with no GF component have a neutral termination, or at least a load side neutral termination? Never seen one so I don't know and the GE's are the only ones I am aware of that exist. If so, it still likely doesn't care about current imbalance as that is what GF protection is all about, AFCI is not the same thing.
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I have heard that Siemens had done away with the afci-- that was the answer I got from their tech guy but I don't think he was aware of what I was talking about.

GE afci hook up the same as the other brands however their dp afci which is really just 2 sp breakers with a breaker tie only use the neutral to one breaker
 
Here is ge's diagram for a dp afci

ry%3D480
 
kwired said:
Does AFCI's with no GF component have a neutral termination, or at least a load side neutral termination? Never seen one so I don't know and the GE's are the only ones I am aware of that exist.
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The breaker needs its own neutral pigtail to get power for its electronics.
Whether it makes a difference to AFCI sensitivity whether you connect the load neutral to the breaker I do not know. I could see the arc signature being twice as large if you look at both hot and grounded leads.
 
GoldDigger said:
The breaker needs its own neutral pigtail to get power for its electronics.
Whether it makes a difference to AFCI sensitivity whether you connect the load neutral to the breaker I do not know. I could see the arc signature being twice as large if you look at both hot and grounded leads.
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I kind of figured they would at least need the neutral for powering the logic elecronics, but was curious as to whether it actually monitors anything connected to the load side neutral or if it is just a place to land such conductor? If so one could connect the return neutral from the load to the neutral bus of the panel and things would still operate "normally". Now if it does monitor current in the neutral, it apparently is not looking for same current that left the ungrounded conductor(s) to return on that neutral like a GFCI will. This could still allow the circuit to work if the load neutral is not connected, but may possibly have reduced performance of the AFCI protection features - assuming they actually do what the manufacturers claim they do that is.
 
The only CB manufacturer to actually remove the internal GFI function was GE. Here is their verbiage on their new AFCI technology.


"Until now, using a shared neutral (multiwire branch circuits) on arc fault protection circuits required the
use of 2-pole AFCI breakers, since the AFCI circuitry uses a ground fault CT to help it detect arcs. But
with GE?s newly developed combination AFCI technology, no ground fault CT is required, so shared
neutral circuits can be used with two 1-pole AFCIs connected together with a handle tie (see Figure 1).
The use of shared neutral circuits produces significant copper savings when two branch circuits are
close to each other but far from the circuit breaker panel. A shared neutral circuit uses 3-conductor
NM-B wire to join two adjacent circuit breakers in the panel to a junction box near the branch circuit
loads/outlets"

My thoughts are that the example given where the improper "Case to Neutral" connection did not trip the AFCI "ARC" Circuit Breaker was simply a fluke moment. Traditionally the AFCI's will react to improper downstream C to N connections. Without all of the actual steps taken it is hard to determine anything other than that at this point.
 
MasterTheNEC said:
My thoughts are that the example given where the improper "Case to Neutral" connection did not trip the AFCI "ARC" Circuit Breaker was simply a fluke moment. Traditionally the AFCI's will react to improper downstream C to N connections. Without all of the actual steps taken it is hard to determine anything other than that at this point.
Click to expand...
But the question is do they react to such a fault because they have the GF component or does the AFCI component see this as a fault condition as well? My understanding is AFCI technology isn't so much about where current is flowing (that is what GFCI technology is all about) but rather characteristics of the current wave form.
 
@kwired,

You are correct in terms of how the GFCI and AFCI function differently. The AFCI is looking for a signature characteristic that is common to an arcing condition, it measures the last half cycles of the waveform looking for this condition. When it is present the AFCI functions as intended. The GFI portion of some CB's are to aid in passing one of the test procedures for UL 1699 but plays no role in the function and the GFI function is not needed IF your technology passes the test without the GFI component part of the assembly, as with GE for example.

In terms of the Case to Neutral condition, I can only assume that in some units the imbalance of current flow causes the internal GFI component to assist in this detection while in those without GFI internal rely on advanced equivalent circuitry that aided in meeting UL 1699 evaluation.

I can tell you the definitive person to ask would be Mr. Thomas Domitrovich at Eaton, as getting in the the internal "HOW" it is done other than explaining the characteristics of the waveform he would be the one to ask.
 
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