Is there a code rule that prohibits "stacking" AFCI breakers on top of each other in a panel? Does the manufacturer recommend or require this?

Theres no problem with stacking ArcFaults. Why would you think there was one?

I received a copy of a home inspection report on a brand new house we just wired. I've never heard of it either. The report states:
"Arc fault breakers "stacked" in the panel - they should be separated by typical breakers"

Then again, another "problem" found was:
"Master bedroom outlets at bed location on arc faults"

The house is big money, a little south of 3 million, and I assume the report is being used as a negotiating tool.

There is heat concern with the heat distribution of the arc fault breakers in a panel. Another concern would be on the 2008 code change requiring arc fault in all living areas of a residential area.

I would say there is a concern with a home inspector who doesn't know what he is talking about.

The typical home report I see around here reports splices in the distribution panel. I have a friend that's a home inspector & he said they were taught about panel splices in class.

I quoted code to him & gave a rough calculation of how many wires and splices you could have in a panel. He said "You really like this stuff, don't you?"

I don't think they're taught NEC at all, I think they're taught what to look for, like a checklist. Sometimes they get confused.

Dave

I do wonder what happens when you get 15 or 20 AFCIs in a panel that is already living in a un-airconditioned garage that cruises in the 35c ambient range anyway. Breakers are usually rated at 40c (105f) or less.
I guess this will be like all the other rules they pass with unintended consequences.
It does sell books, classes and CDs. I think that is the main function of NFPA these days.

"Then again, another "problem" found was:
"Master bedroom outlets at bed location on arc faults""

... You could arc fault the whole house if you wanted...

You should print this page and send it to that guy.

It seems obvious to me that the heat situation pertaining to AFCI's is the reason Eaton submitted the proposal to end the 42 max OCPD's (which has been accepted in principal) in a panel, this will go along with their proposal for all circuits to be AFCI protected.

It will allow more spaces for selective positioning of the AFCI's

See proposals 9-117 and 2-111

I actually don't have a problem with allowing more OCPD's in a panel but, IMHO, Eatons reason for wanting it is way to predictable.

Roger

I like the code panel explination for the proposed AFCI in all living spaces:

"it appears that the intent of the AFCI in the NEC was to create a market for a product where the benifit of the device does not protect against all arcing problems".

More than 15 million AFCI installed to date.

I have not seen anything that said you can't "stack" AFCI or any other breakers. Did I miss that point? Why would there be any more heat with AFCI's than any other breaker? Maybe the manufacturers see that there is not a problem with heat so they are willing to add more breakers to panels? This would be especially true in non-continuous loads.

George,
The extra heat is from the electronic circuits that other breakers do not have. This may become a problem if the whole house rule stands.
Don

Don-

I have not seen anything official on that and was hoping someone else had. Seems that the manufacturers would have provided for that and had the breakers evaluated accordingly.

I have a comment in on 2-142 addressing this specifically. I can certainly see a problem if your garage is cruising in the high 90s and you are generating additional heat inside the panel.
Breakers seem to be rated at 40c. (104f)

George,
Why would you expect that when they have not even made the AFCIs do what they promised they could do in the original proposals some 13 years ago?
Don

edited to add left out word (not)



[This message has been edited by resqcapt19 (edited 09-12-2006).]

Okay Don– Now I get your point. I agree they are struggling to producer a product that meets code. I think most people thought these devices were going to detect series arcs and would also protect hazzards from appliances plugged in the outlets but this was never explained. Currently the devices are only capable of detecting parallel arcs but maybe ultimately series arcs. And I still have not seen anything on any stacking or heat problems.

George,
We only thought that because of the misinformation that was provided by the AFCI supporters. As far as the heat, I'd bet that they have never even looked at the heat when you fill the panel with AFCI breakers. They operate at a higher temperature than standard breakers as a result of the electronics. Whether this will be a problem of not, when you fill a panel with AFCI breakers remains to be seen.

Don

The boys over on the NACHI group (home inspectors) seem to be saying AFCIs run 5-10 degrees hotter than the regular breakers read with an IR thermometer.
I think that may just be anecdotal but it is worth a look by a NRTL when you have a panel full.
I doubt the electronics are good for much more than 70c (the typical non-milspec rating) and that is junction temp, not the outside of the CB case.

Won't it be interesting if the code change in 2008 leads to an increase in house fires, if that causes heat/meltdown problems in electrical panels. Not that I want such a thing to happen, do not get me wrong. But it will probably lead to a review of code making procedures and "ethics" of having manufacturers get so much decision weight, if such an unfortunate result does in fact occur.

I doubt there is any real fire danger. This is more likely to result in more nuisance trips on regular breakers and early end of life of the AFCIs

I'll also sympathize with all the homeowners who have 20 space 40 circuit panels now and they want to add a new circuit in 2008. Will there be any open slots for an AFCI? Will anyone make a tandem breaker that is AFCI? The panels are going to run out of slots if most of the circuits will require breakers that only come in the full size category and not tandems.

There's nothing quite like a Square D QO 100-amp, 32-space subpanel to add those full-sized breakers and circuits they need.

Dave

If they get the arc faults to really work, then we can relax the requirement for receptacle spacing since extension cords won't be a hazard. One receptacle per room again--ah the good old days.

This could really drive down overall costs.

Reminds me of how my bedroom was-- only two outlets in a 15x17 room. It was... interesting to find a place to plug things in. (Then they came in and installed outlets and only two of them share an AFF height, but that's another story).

You'd have the same issues with a 40-space/40-circuit panel.

"You'd have the same issues with a 40-space/40-circuit panel."
Larry, Who makes an AFCI twin CB?
The point Markp is making is there won't be an application for a 20/40 panel if the only single pole breakers available are full size. A 20/40 will just be a 20.

[This message has been edited by Fred (edited 09-21-2006).]

When the 2008 comes out and if the whole house requirement is in it how long would it be before the manufacturers started making AFCI main breakers?
The cost for the mains would skyrocket and the manufacturers could still market the 20/40 panels.

Do AFCI breakers have a high defect rate? 1 of the AFCI breakers I just put in trips even with no load connected. $35 for THAT kind of quality assurance? Gives me a real warm fuzzy on them doing their job if there IS an arc...

AFCI the main? I bet that would be popular. A little water in your outside outlet and the freezer defrosts.

I really don't foresee a main breaker AFCI. I think you're joking(?). Talk about the headaches. Then again, at a two hour minimum per serverce call...

As for the failure rate, I have had quite a few problems with quality as well. I'd say maybe one in ten or fifteen have given me problems, and that adds up. So does the hassle of taking them back. I don't think this new requirement is going to end well...

For you guys that install AFCIs and have problems with them, you need to submitt comments to CMP2. You can do it online until 5PM tomorrow.
Don

I have a comment addressing the effect of heat.

I have spoken with 2 different manufacturers of AFCI CB. The temperature difference from the standard CB to the AFCI CB is the electronics installed in the CB. They are changing the miliamp requirement of the electronics as the technology has improved, and the AFCI CBs that are to be marketed by the fall of 2007 will run cooler, yet still a little warmer than a standard CB. The heat of stacking the current type is of little consequence even now.
I am not a fan of the AFCI breakers yet, but there are issues with installation practices of wiring methods that these devices are bringing to the forefront... that is the poor wiring practices that some out there are performing and blaming on the AFCI tripping. I am not saying there are not issues with the current AFCI, but I (from inspecting) believe that there are issues with the wiring practices that these units do expose.

PCBelarge: Although I respect your opinion and agree that some of the wiring methods I have seen are less than professional, I have been landing panels for about 15 years and have been complimented by nearly every inspector and other electrician that has seen my work. I follow manufacturer spec's when installing AFCI breakers, and any other type of breaker I might be working with, and I don't believe that my methods are causing the issues that I have run across with the AFCI's. I believe that you are correct in that the technology is still evolving, but I feel that the AFCI requirement is being pushed through by the manufacturers prematurely, and I also think that their motivation (profit) is less than admirable.

It's a great idea to be able to impliment any type of device that may increase the safety of an electrical system, but I still foresee trouble in the first stages of implementation of the new regulation, and I think it will be because the technology still needs a lot of work.

I'll relate what I was told NFPA stands for after their "rescue rope" standard debacle in the early 90's:
Not For Practical Application...

I wholeheartedly agree with this. I've done new residential with guys who would trip AFCI circuits at least 50% of the time because of their hack installation techniques: Grounds touching neutrals, paralleled neutrals, shorted neutrals.

All it did was emphasise the fact that this was the quality of their work on every circuit but the AFCIs were merely sensitive enough to catch it.

That being said, I still don't think that arc-faults are the panacea that everyone makes them out to be. I've never had one trip on arc-detection, but seen many trip on ground-fault detection. Might as well throw in a bunch of tried-and-tested GFCIs and be done with it.

-John