VERY annoying electrical problem - cannot figure out - Pro advice needed

[zer0cell]

Hello,
I have a very annoying electrical problem which I simply cannot figure out. I will try to provide as much information as possible. First off, I rewired my entire house - from installing a new meter box, to a new breaker box, the whole thing. All circuits have at least 20 Amp breakers and 12 gauge wire or higher depending on what was required for code. Everything seemed to be working fine. Every circuit was turned on and none seemed to trip. I could use any receptacle I wanted - all good.

Because I got my permit at the end of 2007, I was not required to have AFCI breakers in any rooms except the bedrooms. The electrical inspector came by and used his little tester on various receptacles and all showed up as being fine. The inspector glanced over everything and had no complaints. However, when I completed the remodel and my brother and I moved in we have been experiencing some issues.

First of all, the kitchen is only semi-complete so I did not hook up the big refrigerator. Instead, both of our rooms have a small refrigerator. You know, the kind you have in college dorms. Maybe I am just blind but neither of them had a specification I could find in either the manual or sticker on the refrigerator which indicated the amperage or wattage so I have no idea how much power they are drawing. I can't imagine it would be that much, since they are like 1/3 the size of a regular fridge, and even a regular one has no problem running on a 15 Amp circuit.

I also do not have the central AC on at the moment so those two bedrooms also each have a small AC unit. When I say small, I mean the cheapest $100 one from home depot. I wired each bedroom so that each one is on its own 20 Amp AFCI breaker. So each bedroom has 5 receptacles on its circuit and nothing else. All the lighting in the house is also on its own circuit. I have been out of town for the past 2 months and will be going back soon. I noticed the problem right before I left, as that was when we were getting set up in the house and my brother has had to deal with a problem ever since, which I told him I would fix when I got back.

The problem - is that the bedroom breakers keep tripping. Not the bathroom GFCI receptacle, even when I had my 15Amp sawzall running on it. (this however, would trip the AFCI ones instantly) The water heater is fine and so is everything else except the bedrooms. Almost all the wiring runs through the attic and it does get blazing hot up there as I live in the south. The way in which I wired the receptacles may be a bit unconventional but I had my reasons for it.

See here: http://tinypic.com/r/rr7fw8/7

Note that those junction boxes are in the attic. What is weird is that the tripping of the breakers seems to be very random. Sometimes it will run for days and then they will trip. When you reset them, they appear to be fine until a few days later they trip again. I told my brother to hook the refrigerator up to a different circuit so that the AC unit and the refrigerator are not on the same one. The problem persists... This problem seems to be occurring only in the bedrooms. Not to sound full of it, but I highly doubt I made a bad connection as I am very careful when working with wiring, besides, its not just one bedroom it is all 3 of them. The wires were twisted together in a tight spiral, a wire nut secured tightly, and I even wrapped the bottom of the wire nut in electrical tape to further reduce the chances of a short.


Here are the possible causes I have thought of so far:

most probable:
- AFCI breakers cannot handle either a refrigerator or a window AC unit reliably.
less probable:
- The wiring in the attic is overheating.
- The breakers themselves are located in a room which is not benefiting from the AC.

I'm not sure what else could be causing it. If you think you may know, please help me so when I get back home I can fix the problem.

This is the first time I have even messed with AFCI breakers and I am not impressed. I wonder if code will allow me to replace them with GFCI ones??

 

[larry_g]

I don't have an expert answer but this thread; http://www.garagejournal.com/forum/showthread.php?t=4750

has some of the same symptoms so check it out.

lg
no neat sig line

 

[tfi racing]

- AFCI breakers cannot handle either a refrigerator or a window AC unit reliably.

This is the first time I have even messed with AFCI breakers and I am not impressed. I wonder if code will allow me to replace them with GFCI ones??

#1 is likely the culprit,the appliances are probably appearing as an arc to the AFCI and tripping them.The only solution is to use another circuit on a standard breaker.

#2-No you cannot replace the AFCI with GFCI breakers,they have a totally different purpose.Now if you replaced the AFCI breaker with a standard one for "diagnostic" purposes only,nobody could really say how how long a reasonable testing period is,could they...

 

[mrb]

how old are the AFCIs? could be something as simple as a relay or contactor inside the ac unit sparking when it opens and closes. supposedly newer afci breakers are immune to this but the older ones it was a problem. something else to check is if you drove any stapes too tight onto the romex. you could have a situation where you have a staple that cut into the insulation and as the cable heats and cools it causes the afci to trip

 

[walrus]

Motor loads can trip AFCIs

 

[sdowney717]

this was not a new service, right?
My inspector told me upgrades, which I did, meant no requirement for GFCI or AFCI breakers.
So I dont have any and no nuisance tripping.
did that upgrade 2 years ago.
Sure, maybe they are nice to have but what of the hundreds of millions of installed circuits
which just have standard breakers??

 

[zer0cell]

Thanks for the responses.

@sdowney717:
It was considered new service since all the electrical was new, including a new pole. It certainly is a nuisance...

@walrus:
So even if the appliance in question uses far less amps than the what the circuit breaker is rated for it can still trip it randomly like that? In the case of the sawzall (15A) it was obvious that it overloaded the circuit (maybe just at start up) because it tripped immediately. In this case however, it can be hours or days between the tripping.

@mrb:
Driving the staples in too much makes sense, but I don't think I would have made that mistake, especially not so many times... I hope that's not the case though because some of them are behind drywall The breakers were purchased in 2007 or 2008. I got them from home depot. Do you think they would all be defective or have this issue?

@tfi racing:
That is probably what I'm going to have to do... is replace them after the final inspection... at least temporarily until the fridge in the kitchen is hooked up again and the central AC is on again. Even so... does that not seem strange that if the AFCI breakers are at fault then people cannot, according to code, have a mini fridge in their room since every receptacle in a bedroom needs to have AFCI protection? I don't get it, how does one use a window AC unit if it will cause the breaker to trip in the bedroom? Am I missing something?? How can this not be possible?

@larry_g
Thanks I will look at it...

 

[walrus]

@walrus:
So even if the appliance in question uses far less amps than the what the circuit breaker is rated for it can still trip it randomly like that? In the case of the sawzall (15A) it was obvious that it overloaded the circuit (maybe just at start up) because it tripped immediately. In this case however, it can be hours or days between the tripping....

I doubt it overloaded it, its senses a fault and trips. AFCIs are known trouble makers whether a real issue is present or not. Their are questions to whether or not they really work or are they another code solution sold by an electrical manufacturer. If they weren't so expensive I'd tell you to try another. I'd check all your connections in every box related to those circuits. You're not sharing a neutral between circuits are you?
I use an extension cord to plug in my treadmill from my dining room to my bedroom, my AFCI trips every time the treadmill is turned on. My Vac trips it sometimes not always. Lights, fans are no issue?

 

[zer0cell]

I doubt it overloaded it, its senses a fault and trips. AFCIs are known trouble makers whether a real issue is present or not. Their are questions to whether or not they really work or are they another code solution sold by an electrical manufacturer. If they weren't so expensive I'd tell you to try another. I'd check all your connections in every box related to those circuits. You're not sharing a neutral between circuits are you?
I use an extension cord to plug in my treadmill from my dining room to my bedroom, my AFCI trips every time the treadmill is turned on. My Vac trips it sometimes not always. Lights, fans are no issue?

Okay, that makes sense but the funny thing is it is happening in more than one bedroom. Two bedrooms currently have a small refrigerator and a window AC unit in each which are on 24 hours a day. None of the circuits have a shared neutral. The bedroom lights are on a separate circuit. Each bedroom has 5 receptacles on an AFCI and that is it. My brother tells me it is happening even when he does not connect an additional appliance. It appears to happen at random.

I was really trying to make sure when I wired everything in the house that I would not skimp and use 14 gauge wire, or add too few receptacles etc. and if a problem arose, that it would be easy to know which location in the house the problem was. There are a few things I may have done differently now when looking back but still I was pretty pleased with my work until now. I hope its not something that I did wrong, but if it is I have no idea what it could be and it seems weird that its on both.

I will check all the wiring again as you suggested. Even though the breakers are only a few years old and the appliances are all brand new... do you still think they would trip the breaker of an otherwise well wired circuit? How would one even use a window ac unit or a fridge in the bedroom, have a dedicated circuit for that with a gfci receptacle? Would that be acceptable for code?

 

[walrus]

I will check all the wiring again as you suggested. Even though the breakers are only a few years old and the appliances are all brand new... do you still think they would trip the breaker of an otherwise well wired circuit? How would one even use a window ac unit or a fridge in the bedroom, have a dedicated circuit for that with a gfci receptacle? Would that be acceptable for code?

GFCIs are only used in wet areas, everything else in 08 code is AFCIs. I don't do residential work but I have friends who do and they have issues at times. I'm not sure how they work them out. In Maine window air conditioners aren't a big item(although after this summer their may be more sold) so I haven't heard about AFCIs and AC units. A dedicated circuit seems to be a good idea though but it would still have to be a AFCI.
What brand AFCI are you using?

 

[zer0cell]

Square D if I remember correctly...

 

[Charles (in GA)]

You've heard all the explanations already, the Arc Fault breakers are tripping, not because of an amp overload, but rather because of an "arc" detection, caused by the A/C units and the fridges.

Swap the breakers for regular breakers and forget about it. People have lived for years with regular breakers, Arc Faults must be the invention of someone's brother in law I think, who needed to sell them, because they are questionable in their ability to function properly.

Charles

 

[Aceman]

Since you most likely don't own a megger my advice would be to unplug the ac and fridge from the bedroom circuits for a few days to see if the breakers still trip. Run an extension cord to them from somewhere else if you have too.

Then you'll know for sure that it's the ac/fridge and not your wiring that's causing the nuisance trips. Which I bet it is....

 

[zer0cell]

Thanks I will try and let you know how it turns out...

 

[sdowney717]

http://www.electriciantalk.com/f2/afci-nuisance-tripping-3916/
I dont like AFCI nusinace tripping

I just love all the negative talk about AFCI.
for example they trip when you use a vacuum cleaner, so plug the vacuum into the GFCI bath outlet. And the problem is not the AFCI, it is the vacuum cleaner motor windings!

And this, the inspector says, after the inspection passes take them out and put in normal breakers.
And how normal breakers are soo cheap, the manufacturers need to improve profits so they are colluding with the NEC to force the change.

 

[rodnok1]

Those little cheap fridges are just that cheap, more than likely you could plug a reg fridge in and it would be fine. I second swapping the breakers until you get done remodeling.

 

[jwillis]

I keep wondering why each of you have to have a fridge in your bedroom. I know you said the kitchen fridge was not plugged in to the kitchen, but couldn't you have put it out in the garage and used it until the kitchen is done? Are they going to be there after you finish your kitchen? I have a fridge out in my garage but one in each bedroom is kinda funny. But when you click on the TV, fridge and A/C that is quite a bit of a load in each bedroom. Good luck....j willis

 

[gfd_703]

http://www.thecircuitdetective.com/afci_circuit_breakers.htm

Check this out I think it might help

AFCI Circuit Breaker Troubleshooting
An arc-fault circuit interrupter (AFCI) is a circuit breaker located in your electrical panel that serves the functions of a normal breaker but also senses hazardous arcing on its circuit and will trip off for this. It can be identified by the special colored test-button near its handle. (Ground-fault breakers also have a button, so read with a magnifying glass to be sure which kind your breaker is.)

AFCI breakers began to be required by Code in 2002 for new wiring supplying bedrooms. The areas to be protected were expanded in 2008 (where that national Code has been adopted locally) to most rooms of the home. The areas left out of the requirement were garage, bathroom, kitchen, and laundry; these were already required to have ground-fault protection. Apparently two-fold protection is considered overkill.

It is relevant to AFCI circuit breaker troubleshooting to note that overkill was, however, required of manufacturers from the beginning: the arc-fault circuit interrupter must have a degree of ground-fault protection built into it as well. The rationale seems to have been that as long as a new device (the AFCI) was being designed, it should incorporate super-safety by tripping off for ground-faults too. At first, the level of ground-faulting was not required to be as strict as GFCI outlets around the home have. But by now, I understand that many AFCI brands have the same sensitivity as the GFCI outlets. It would make sense that the Code should simplify itself (and life) by just requiring all 120-volt wiring in the home to have protection from AFCI circuit breakers which incorporate the more sensitive ground-fault protection. Then all these GFCI outlets around the home could be eliminated.

These facts present a problem for AFCI circuit breaker troubleshooting. When these breakers in newer homes trip off, there are five possible causes:

An Overload -- when electrical usage would have begun to overheat a circuit's wires
A Short Circuit -- very high current resulting from a fault on the circuit
An Overheating Breaker -- when the breaker itself has poor contacts or connections
A Ground-Fault -- leakage off of the intended circuit. In this I include shock hazards, neutral to ground faults, and the "fault" that occurs to the phase of another circuit if these two circuits share one neutral.
An Arc-Fault -- sparking happening on the circuit or its lights or appliances
A standard breaker will trip for any of the first three causes above, and it can take some thought and investigation to determine which cause is at work. But the fourth and fifth causes add even more complication. Which of the five causes has tripped an AFCI breaker can be quite important in how you go about solving the problem.

If the AFCI breaker lets you reset it and does not repeat its tripping, you do not need to know or to worry about the cause. For the record, it was probably an overload or an arc-fault that was only a one-time event.

If the arc-fault breaker re-trips immediately (up to 5 seconds) when you reset it (see How to be sure you have reset), this is typical of a short circuit or a ground-fault. If re-tripping only occurs from one minute to one month later, the cause is more likely an overload, an overheating breaker, or an arc-fault.

For systematic help to troubleshoot these various causes, see Troubleshooting or Diagnosing. In order to tell specifically whether it is an arc-fault that is causing repeated tripping, you might have to temporarily replace the AFCI breaker with a standard breaker (putting the solid white wire from the AFCI's terminal into the panel's neutral/ground bar). If the standard breaker holds, then the problem is either an arc-fault or a ground-fault. If so, you could then introduce A GFCI receptacle (with a white piece from the neutral bar to "line" neutral on the receptacle) after the standard breaker. If the GFCI holds, the problem was an arc-fault; otherwise, a ground-fault.

If you have a recurring arc-fault, rather than one of the other conditions that will trip an arc-fault breaker, what signs will you be looking for out on the circuit? Although you might find something melted, charred, or sooty, an arc is more likely to trip the breaker without leaving visible signs. In any case, if the tripping continues to repeat without much delay, the Procedures for diagnosing the location of a short should be applied.

Also, as long as you do not leave it in place beyond your time of vigilant searching, a standard breaker, as mentioned above, could be put in the panel in place of the AFCI. You might then be able to hear, see, or smell signs of heat or arcing; blinking lights on the circuit would give additional clues. I am comfortable suggesting what might sound like playing with fire, because few cases of arcing are ever able to start fires. In most homes (most don't have AFCIs), when arcing at connection points ("series" arcing) has been happening for a while, it does commonly show itself eventually as a partial outage of the circuit, from the arcing point on. This can then be troubleshot more easily. But a 2005-or-later AFCI may not let the problem get to the point of interrupting power in this way; if the series arcing is large enough, this AFCI would stop the arcing before it could start to affect things in this way.

What is the difference between series arcing and parallel arcing? Series arcing (a kind of partial open) would occur along the normal circuit path, typically at connections meant to pass the normal current of a load along. With parallel arcing, on the other hand (as with a short circuit), current runs from hot to neutral or to ground, unlimited by any loads of the circuit.

How common in practice are arc-faults? In all my troubleshooting, from when these protected circuits began to be required for bedrooms in 2002 up to the present, I have not once been called on to deal with a repeatedly tripping AFCI. This may change a little beginning in 2008, because more rooms of new homes must have the protection. So far, the arcing faults an AFCI will interrupt do not seem to me to be very common at all.

Many people will think that a tripping breaker has something wrong with it. This would be rare. One reason an AFCI would trip immediately is that its white neutral or that of the circuit is not hooked up right (this will be a case of tripping for a fault -- namely the fault of the installer). The most common way an AFCI is actually bad is when its Test button will not trip the breaker. With that, there isn't much AFCI circuit breaker troubleshooting to do; just replace it; there is something wrong with it.

Finally, a note on how Code on AFCIs will affect new wiring practices. Where the 2008 national Code is adopted, dining rooms are required to be AFCI protected. Since dining rooms receptacles are commonly put with some kitchen receptacles on one circuit, and since such kitchen outlets have a GFCI requirement, there may now be a circuit run from an AFCI breaker that will also have a GFCI outlet along it. With the AFCI already sensing a degree of ground-faulting, there might be a potential for nuisance tripping or at least confusion over where a ground-fault is occuring. An alternative is to add one more AFCI breaker to the panel to serve just dining room receptacles.

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[BillK]

Zero,

Regardless of all of the other answers, the first thing you really need to do is find out how much current the AC's and the little Fridges need. There are not many window AC's that I have seen that do not specify a dedicated outlet. I would bet that combining the AC with the fridge, especially if both of them decide to start at the same time, will pull more than 20 AMPS. Until you find out what the current draw is for these two things, I personally think you are wasting your time on everything else.

Both the appliances (AC & Fridge) should have a lebel on them somewhere or go to the manufacturers web site and find the specs.

Just my opinion,

 

[Greatbear]

Motor loads play hell on AFCI breakers. Even small dorm-style fridges draw a substantial surge at start-up despite needing at worst only a couple amps while running. an air conditioner, even one as small as 5000 btu will draw 30 amps or more on initial startup. An AFCI does not respond as much to current surges as much as it does to high-frequency short-duration current waveforms that are caused by arcing. If an appliance is turned on when the ac voltage is at it's negative or positive peak, the resulting sharp square-wave current impulse will likely trip the AFCI. Anything with a universal (brush-type) motor like a vacuum or power tool has a very noisy current waveform with lots of high-frequency "edges" to it, and these will nuisance-trip AFCI breakers. The earliest models of AFCI breakers were a bit sensitive, the newer dual mode units are a bit more refined. You can sometimes alleviate the nuisance tripping by putting a line noise filter between the outlet and the load. Unlike a surge protector, the noise filter has a network of capacitors and inductors meant to filter line noise out of a power source before it gets to the load. Likewise, if the load itself produces noise, the same filter will attenuate this from reaching the outlet, since the filters are bidirectional. This will act to "soften" the current impulses seen by an AFCI breaker and keep it from tripping in many cases. Corcom makes turnkey inline filters along with devices meant to be installed inside equipment.

 

[Norcal]

Do the AFCI's trip w/ out a load or do they only trip w/ a load? IMO your going to have to check every device, box in those circuits to make sure there is no grounding conductor touching a neutral terminal on a receptacle, mixed neutrals* from other circuits, AFCI's have 30ma GFCI protection in addition to the "arc detection circuitry" & simple wiring errors can play havoc with the circuits.


* A example would be connecting a neutral from a lighting circuit & one from a receptacle circuit, that will cause some issues w/ a normal circuit but will make life hell w/ a AFCI circuit.


A properly made up splice using a wire connector such as wire nut or wing nut does not require tape around them, it just raises a red flag when troubleshooting that there are bad splices in the box.

 

[jay50]

I've see this happen and the problem turned out to be a nicked wire due to a staple that slight cut into the wire.

Isolate the circuit and remove all the loads and see if it happens again. If it does, then you have a short due to this condition.

Get ready for some fun then....

 

[cowboyjosh]

Im betting your cheap fridges and window ac units are the culprits in this problem. Cheap is cheap, I see this all the time with vacumms; Dyson's for example are the most expensive junk vacuum folks can buy, they put cheap Panasonic motors in them in the USA (so that they run on our 120 volts) and once they wear a bit causes AFCI's to trip whereas a quality vacuum motor like that in say a Kirby or Miele causes few if any issues with AFCI breakers; when someone calls us with such problem we always ask about the devices plugged into the offending circuit, often times they eliminate the cheap window AC unit or in your case the fridge the problem will likely go away.

Another thing when wiring or re-wiring a house is to put multiple circuits in for bedrooms. I didn't do it on my house because the AHJ wouldn't allow it, but I also like bedroom lighting on a seperate breaker then the bedroom outlets, I also like to wire every other outlet in a bedroom to two separate breakers, those 2 breakers can then serve 2 bedrooms. In other words, I like to over wire.

 

[djb2]

You can sometimes alleviate the nuisance tripping by putting a line noise filter between the outlet and the load.

The noise filter will remove the high frequency component of the current draw that the AFCI recognizes as arcing. It effectively disables the arc fault detection, turning the breaker into an less reliable, more expensive version of a standard breaker.

That may be the desired effect if the goal is to conform to the letter of the electrical code while eliminating annoyance trips. But everyone should be aware that it's not a fix but a bypass.

I have a few 'spark monster' appliances, including my vacuum cleaner, an older heavy-duty drill and a hand mixed. Their common theme, besides being able to trip sensitive AFCI breakers, is that I'm right there operating them.

IMHO, AFCI breakers should not have been mandated when there are common appliances that trip them. A slight increase in technical safety at the expense of far more nuisance trips will result in a long term decrease in safety. We are training people to treat breaker trips as common, harmless events rather than warnings.