Just have to hear it from the field. How many people out there have installed AF Breakers? Any problems with tripping? Any horror stories? Anybody have a tripped breaker that they went back out to and found a problem? I would like to hear anybody about any story about arc fault breakers.
For the most part, they went in with no problems that a little troubleshooting couldn't quickly find and fix.
One of the bedroom lighting circuits was a different matter, though. No matter how we searched, we could not find the cause of the triping. In the end, we cheated, put in a regular breaker, and simply labled it 'lighting.'
We speculate that the complexity of the circuit ..... a multitude of dimmers, three-way switches, and fan/light combos .... may have been the cause of the problem.
That job was a good five years ago - I try not to get involved in new home construction - and things have worked well so far.
In new resi, there are unually no problems if it is wired correctly(no shared neutrals). I had to troubleshoot my own wiring once. Took me several hours(up and down the stairs to reset the breaker)until I finally found a shared neutral in a switch box. I learned that lesson. More of a problem is just bad breakers. I will put power on the house and they won't hold. I replace it and everything is good.
The bigger problem is remodels and additions. You can't just find a hot in the attic or crawl somewhere and tap on because you don't know how its wired.
The last issue is panel space. With the 08 code, you can end up with several afci breakers in the panel. They are not small but rather crowd into the neutral and ground bars.
I don't have any real horror stories, just a bunch of "Ahh Crap" stories.
For at least the last 4 years, we've had to put them on all bedroom circuits here in Orange County, CA. This usually requires 2 to 4 AFCI's per panel.
As Reno stated, I have also had problems with the lighting circuits, and dimmers seem to be the common thread when those problems arise. I'm not an engineer, but it seems to me that perhaps chopping the wave form, as most dimmers do, creates a "bug" for the AFCI system that causes problematic tripping.
I also got a call about a month after completion of a new construction home related to a constantly tripping AFCI breaker. I performed every test imaginable, including a megger, on the home-run portion of the circuit, and each branch (while isolated), and was unable to find a problem. A new AFCI lasted about another month before it started doing the same thing. I had to finally conclude that something the resident was plugging in was causing the problem, and just replaced the unit with a standard breaker. Problem solved, although I'll admit to cheating it.
Conclusion? AFCIs are not completely ready for the '08 NEC requirement. There are technical issues that the manufacturers need to iron out and, IMHO, the NEC jumped the gun on this one.
Also, there's the issue of panel space. They have yet to develop/release a tandum AFCI.
I avoid new construction too, but since I really only do service work anymore, I encounter a lot of problems with installations done by others. Most recently, I went to a pretty big house (2 yrs. old) that had three 200 amp, 40 ckt. panels. The original EC put all heavy loads (furnaces, heat pumps, ranges, etc.) in one panel, GPA and medium-duty circuits in the second one and all lighting/SA circuits in the third. There were eight AFCI breakers all together on one side of the panel that were tripping randomly and for no apparent reason. These were Square D QO panels.
I couldn't find anything wrong, so I contacted Square D. About a week later, they contacted me and suggested that I separate the AFCI breakers by one space to see what happened. There was plenty of room in the panel to do this, so all I needed to do was put in some blank filler plates. I wasn't crazy about doing this since it threw the load balance off, so I did the same thing on the other side of the panel with the standard breakers, just staggering them on opposite poles.
We never had another problem after that. They suggested that we try to minimize grouping AFCI breakers side-by side for more than two at a time due to potential heat. I never followed up after that except to stick to that rule with any brand from there on-out.
I'm a bit of a perfectionist, so I'd prefer to keep all similar breaker types grouped together. I like to start at the top with the two-pole breakers, largest on top. I then like to start at the bottom of the panel with single-pole 15's, then 20's above those. Any blank spaces are left in the middle so growth can fill in while still maintaining this arrangement. I guess I'll have to adapt.
I've installed 2, one for the lights and smokes in my bedroom and one for general circuits. Haven't had any real issues. I do have to run an extension cord outside the bedroom to run my treadmill. It will trip the AFCI everytime