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"So when the next NEC requires AFCI for nearly every circuit in the house, how will you stagger the breakers? "

Actually I brought that up in a comment on the 2008 and NFPA rejected it as unfounded. They refuse to believe there would be a problem with a panel, stuffed with AFCIs, even at ambients approaching 40c.


Greg Fretwell
Joined: Feb 2002
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H
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John, will figure out why I asked the question. It is because here in NJ we are getting ready to adopt the '08 NEC. I still don't think that the AF breakers have proven their reliability. Since NJ doesn't require them yet, I need some of the people out there who have used them. Right now NJ will adopt the '08 and use AF breakers on new construction only. We have a separate code for rehab houses. Anymore stories out there? I would like to know them. Thanks.

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G
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They've been required and used in Chicago since 2000.
Most of the problems that I see are caused by sharing neutrals (old habits die hard) and by plugging in loads that cause the AFCI breakers to trip.


Ghost307
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pdh Offline
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So when do the 84 circuit panels start to show up in the regular markets rather than the underground?

pdh #181699 10/24/08 03:27 PM
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pdh Offline
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Anyone know of any bad experiences (false trips) when a large UPS (1200 VA) serving computers is connected to a circuit protected by an AFCI breaker? How about a small neon indicator lamp?

The kind of UPS I am interested in the effects from is the "dual conversion continuous online" type, that is always converting the input AC to an internal DC, paralleling with the internal battery through some control circuit, and then converting that DC back to near-sine-wave AC to supply its outlets.

pdh #181742 10/28/08 07:06 AM
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Originally Posted by pdh
Anyone know of any bad experiences (false trips) when a large UPS (1200 VA) serving computers is connected to a circuit protected by an AFCI breaker? How about a small neon indicator lamp?

The kind of UPS I am interested in the effects from is the "dual conversion continuous online" type, that is always converting the input AC to an internal DC, paralleling with the internal battery through some control circuit, and then converting that DC back to near-sine-wave AC to supply its outlets.
They make AFCI breakers rated for 1200kVA? I don't think it's a requirement, though you'd likely have to have ground fault protection built into the switchgear serving it. I've seen some problems with harmonics from the UPS rectifier in a pair of 500kVA UPSs causing relays in the switchgear to go nuts (my kingdom for a PLC!), but installing input filter cabinets fixed it. There's no hard and fast rule, but I like to spec out UPSs with less than 13% THD if it's a significant % of the generator/building load. Some of the better 12-switch UPSs meet it inherently, but nearly all 6-switch rectifiers (VFD, UPS or otherwise) need to have an input filter or the THD is just ridiculous.

Edit: wait, 1200VA or 1200kVA? You threw me off when you said "large" instead of "desktop"!

Last edited by SteveFehr; 10/28/08 07:14 AM.
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pdh Offline
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It's "large" in the sense that it is larger than the stuff you might buy at places like Best Buy or Circuit City. It took 2 people to lift it, probably due to having dual batteries inside, same as the next higher capacity unit that requires a dedicated circuit.

I haven't heard of computers causing AFCI issues, so I'm assuming modern PSUs are clean enough.

pdh #181767 10/29/08 10:42 AM
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I've had to install them since around 2002 ish.
We started by protecting just the bedroom receptacle circuits as per the 99 code but later included all outlets.

I've been using GE in both single pole and two pole in new construction and I can't say anyone has reported a nuisance trip.

I recently used CH type BR in an addition and had one trip a couple of times. The first time I suspect my fat finger hit the trip button as I was closing the panel but the second one is still unexplained.

I've always grouped them together with no problems.

The biggest problem (other than high cost and completely changing how I might design my circuits) is the space they eat up in a 20/40 or a 12/24.

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pdh Offline
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Originally Posted by ChicoC10
The biggest problem (other than high cost and completely changing how I might design my circuits) is the space they eat up in a 20/40 or a 12/24.

I've long believed that it would be a better panel design that would integrate the neutral bus along side the non-neutral bus, and allow breakers to have 2 connections into the bus, instead of just 1. That would eliminate all the pigtails that panels are going to be full of in the coming years. But such a thing would be an all new standard most likely incompatible with what exists now. So it is unlikely any manufacturer would want to switch to it.

pdh #181821 11/02/08 10:42 AM
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Cat Servant
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.. incompatable ...

Funny, it actually seems that some firms - Square D in particular - do all they can to ensure that their panels are unique.

Don't encourage them laugh

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