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

[zer0123]

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??

[jadnashua]

AFCI are designed to detect arcs, as indicated by the name. A brush type motor makes arcs. It's almost certain that your saw used a brush type motor, and the frig and a/c units may as well. I think you'll have trouble if you plan to leave those things on AFCI breakers. Things like lamps, electronics, and most heating pads don't normally generate arcs nor do they have brushes in their motors, so those things, more common in a bedroom, wouldn't create problems. It sounds like the breakers you have are doing what they were designed for, and tripping when detecting the arcs from those motors. Brands vary in their input circuits as to how sensitive they are, and whether they detect that the arc is dangerous or not and likely to overheat things and start a fire (which is why they were legislated).

If you could run the frig and a/c units off dedicated circuits, or move them elsewhere other than circuits protected by AFCI temporarily, I think you'll probably find the problem goes away.

[zer0123]

Okay, I will give that a try. You would think that a brand new mini-fridge and a new window ac unit would have been designed with AFCI breakers in mind... That's what doesn't make any sense to me. How is someone supposed to put a mini-fridge in their room or dorm room, or even use a window AC unit? Even a dedicated circuit run to that bedroom would need to be AFCI by code right? I've heard that even refrigerators are supposed to be on AFCI now. How is that possible? This all just seems strange to me...

[jadnashua]

Not all motors are brush-type. As experience increases, they have been tweaking the arc detection circuitry and they are better now than when they were. While I don't necessarily agree to their mandate, it is what it is. A dedicated circuit to something like an a/c unit might not require an AFCI breaker...I'm not sure. You'd have to read the code carefully to determine.

[drick]

Do you have a Cutler Hammer panel and breakers? Back around 2006 my company went through a period where 10-20 percent of the arc fault breakers we installed were , um, faulty. The problems include what you are describing. Also whenever we ran into one bad arc fault there were always others in the same shipment that were also bad. Eventually whenever we got a call about a randomly tripping arc fault we had installed our solution was to replace all the arc faults in the panel with ones we purchased from another supplier. I cannot think of one case where this did not fix the problem. Wait, I can think of one, but it involved computer equipment - go figure.

Anyway the problems I saw were with Cutler Hammer, but even if you have a different panel my recommendation is going to be the same: Replace all of your arc faults with new ones. I'd be willing to bet you never see the problem again.

Also if small motors were causing all arc faults to trip everyone with an arc fault and a window a/c, fan or vacuum would be complaining and they are not.

-rick

[hj]

Motors, such a refrigerators, frezers, and water coolers, CAN randomly trip even a GFCI breaker. I have had customers with all three problems, so I would expect it would be even more prevalent with an AFCI.

[ballvalve]

I would take out the AFCI unless you used aluminum wire, and do what the world did fine with for 100 years. Since we are soon to be mandated to have fire sprinklers inside, they might as well remove the AFCI politically demented requirement altogether.

Those little fridges are power hogs, and if you build them in, can run non stop forever. I think they are outside the energy saving specs, and I'll bet a real 18CF Kenmore uses less power.