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#89136 09/03/04 10:58 PM
Joined: Feb 2004
Posts: 41
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rknikko Offline OP
Member
I know that we cannot share the neutral or ungrounded wire for AFCI. Which mean no multi circuit wiring, otherwise we will need a 2 pole AFCI. BUT what about wiring the lights and receptacles under the same circuit? Will that cause the AFCI to trip? Will that cause the unbalance in neutral?

2017 / 2014 NEC & Related Books and Study Guides
#89137 09/03/04 11:33 PM
Joined: Jul 2004
Posts: 9,645
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I can't see where the unbalance would occur.

My worry has always been that every bedroom in a home would end up on one 20a AFCI. Using the 3va/sq.ft rule you could have 800 sq/ft of bedrooms on one circuit.


Greg Fretwell
#89138 09/04/04 08:20 PM
Joined: Mar 2001
Posts: 345
T
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Quote
I can't see where the unbalance would occur.

My worry has always been that every bedroom in a home would end up on one 20a AFCI. Using the 3va/sq.ft rule you could have 800 sq/ft of bedrooms on one circuit.
The US NEC requires that the load be balanced so you have to evenly proportion the square footage over the Lighting and appliance branch circuits that are the result of the square footage computation. In other words if two thirds of the square footage is bedrooms then two thirds of the required L&A circuits must be used to serve them. If you install more L&A circuits than the code requires you still have to evenly proportion the square footage or the outlets over those circuits.
--
Tom H


Tom Horne

"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
#89139 09/04/04 08:34 PM
Joined: Jan 2003
Posts: 4,391
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Moderator
Tom I have heard that from other people and I have also heard that is not the case.

I really do not know the answer, where does the NEC spell this out?

Bob


Bob Badger
Construction & Maintenance Electrician
Massachusetts
#89140 09/04/04 09:54 PM
Joined: Jul 2004
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If someone is building to minimum code why would you expect the rest of the general lighting circuits to work out to much less than 3va per foot? 800 sq/ft is a lot of "bedroom" in a 1600 sq/ft house.


Greg Fretwell
#89141 09/04/04 10:23 PM
Joined: May 2003
Posts: 2,876
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e57 Offline
Member
Now isn't the 3va/sqft deal for calculation, not connection?

The circuit needs to be sized for what it is connected to....

Balance is not required, but strongly implied that some idea of balance on the connection is what they're looking for right?

Anyway, rknikko, I have had problems with AFCI's on certain types of loads. Dimmed LV lighting, flouresant lighting, and a flat screen monitor. If this type items have problems on a 2-wire circuit, why bother trying to chance it with a 3-wire?


Mark Heller
"Well - I oughta....." -Jackie Gleason
#89142 09/05/04 02:16 PM
Joined: Jun 2004
Posts: 220
T
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I beleive 210-11(B) talks about this.

#89143 09/05/04 04:33 PM
Joined: May 2003
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e57 Offline
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Yeah, was going to mention it, but started ww3 before on it....


Mark Heller
"Well - I oughta....." -Jackie Gleason

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