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Stacked AFCI's


DonTx
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I hadn't heard that before. They have always been stacked together in the houses I've seen.

I try to run my hand down the breakers to feel any heat but to be honest I bet I don't do it on the newer stuff. I guess i should. Have you seen any differences with a laser thermometer.

Buster

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Hi,

I did to the studs remodel yesterday where the electrician had, for reasons unknown, installed a sub-panel next to the new service panel and every circuit in that sub-panel had AFCI protection. My theory is that those are K & T circuits that were left in place, but I couldn't prove it.

Anyway, no excessive heat at that panel and it had ten AFCI's in it, five to a bank and all one on top of another.

ONE TEAM - ONE FIGHT!!!

Mike

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Originally posted by Donald Lawson

Is there any truth that AFCI breakers should not be stacked in a service panel because they can build up heat?

If so, is there any documents to back this up?

Thanks

Donald

No, the heat is normal. At least that's what we think now. Wait ten years and ask again.

The AFCI breakers have an internal power supply that generates some heat even when there's no load on the circuit. In addition, when there is a load on the circuit, there'll be some I²R losses that create heat just as there would be in a normal breaker.

If the panel has more than a few AFCIs and they're stacked together, the problem gets more severe. As I recall, typical residential breakers are rated for use at an ambient temperature of about 104 degrees. They'll still work at higher temperatures, but they may trip more easily.

If someone's having a problem with nuisance tripping and there's a big stack of AFCIs, it might be worth separating them to see if it helps.

By the way, I'm becoming more and more convinced that AFCIs are pretty much useless. At least they certainly aren't worth the aggregate amount of money that is being spent on them across the nation.

- Jim Katen

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Originally posted by Terence McCann

Jim stated:

**By the way, I'm becoming more and more convinced that AFCIs are pretty much useless. At least they certainly aren't worth the aggregate amount of money that is being spent on them across the nation.**

Why is that Jim?

I'll give my reason for agreeing w/ the Katen.

They're only required in new construction where we have outlets every 8-12 feet. In other words, the base reason for having them (too many extension cords in old BR's), is eliminated by adding outlets. Where's the hazard in BR's in new construction?

When they are required to be retrofit into old Section 8 rental properties, I'll get behind them. For the time being, they are a perfect example of large amounts of money being thrown @ a problem that doesn't exist.

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The microprocessors in AFCI circuit breakers do produce heat. When the circuit breakers are stacked the temperature rises. I haven't been able to find an authority which states the breakers shouldn't be installed stacked nor have I found anything which addresses a temperature limit above which one should be concerned. In my house, which I built three years ago, I had the electrician seperate the AFCI breakers by at least two regular breakers. I have no hot spots on the dead front cover of my MDP's

NORM SAGE

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Douglas gave an excellent class on these at IW in January, in which he more or less agreed with Jim's accessment as far as the current generation of AFCI's goes. For the life of me I can't pull up the details in my weary brain right now, but as I recall he had more hope for the next generation being a genuinely meaningful safety item.

Can anyone else who was there help me out with the whys and wherefores? Warga? Jimmy?

Brian G.

What Was My Name Again? [:-crazy]

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Originally posted by Terence McCann

Jim stated:

**By the way, I'm becoming more and more convinced that AFCIs are pretty much useless. At least they certainly aren't worth the aggregate amount of money that is being spent on them across the nation.**

Why is that Jim?

There are two basic types of arcing in a household electrical system, series and parallel. Series arcs occur when there’s a break in a wire or when there’s a loose connection; the electricity is traveling along its intended path but has to jump over the break. Parallel arcs happen when there’s a short circuit between two different conductors, for instance between a hot and a neutral or between a hot and a ground. This last condition, a short between a hot and a ground is also called a ground fault.

The present generation of branch circuit AFCIs only protects against parallel arcs, they’re useless against series arcs such as those you’d get with old aluminum wiring, loose connections at receptacle terminals or stab-backs, loose wire nut connections and broken or partially broken wires.

They will protect against hot-to-hot shorts and hot-to-ground shorts. Of course regular breakers will protect against those too. The AFCI’s will just do it more quickly and at a lower threshold.

So for all those times when you drive a nail through a piece of Romex and it makes enough of a path between the hot and the ground to cause an arc, but not enough of a path to trip a conventional breaker, the AFCI will save your butt.

In the final analysis, these things only protect against a tiny portion of the arcs that can happen out there (beyond what regular circuit breakers do). That said, the next generation of AFCIs should be much more useful.

- Jim Katen, Oregon

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In most new panels I've seen with AFCIs, they are generly grouped. I don't recall ever having an issue with it causing any trip problems.

The real problem that I have with AFCIs is do they actually work. Like with a lot of devices or certain materials required by the code, you wonder should they actually be required or just suggested by the electrician. There are a lot of manufacturing representatives who take a device that a company has developed and tested under certain circumstances, get a UL listing for that application. Then they lobby to have it adopted into NFPA 70. Don't get me wrong, I beleive that the people that are on the code commity are commited to life safety and are convinced by these people that their product can save lives. For instance, the GFCI recepticles, has anyone noticed thay have gone up in the last year about 3 or 4 dollars? Thats because UL found out that after these things trip a few times the fault protection is depleted to the point of no prtection at all. Now, they have some sort of internal sensor that will not allow the GFCI to reset if it has been damaged, some have a light. But how many people are out there using GFCIs that don't have any protection. Same with AFCIs, they developed them, tested them, somewhat, and threw them on the market. Seimans AFCI's would not reset in unheated garages in the winter here below 65 degrees, that was a recall. To my knowledge,none of them can share a common nuetral with another circut or they will trip. Thats the reason you don't see them in old work, you can't track down were the nuetrals are going and feeding what devices. I have heard of a AFCI recepticle that is in developement or has been developed. What good is that for concealed wiring in the walls? These will probably be required in bedrooms of houses for replacements. Does anyone have any stats that show how many less fires there have been since these were required January 1, 2002. I'll bet you don't. Ok I'll shut up. Thanks ,

Troy

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