It seems that when wiring a new residence, if you feed the homeruns to the device boxes closest to the panel, less cable could be used. However, the more I think about it, I don't think it is true. What do you guys think?
Obviously, homerunning the farthest device would waste wire if you then had to back track to feed devices that you passed over on the way. I'm just not convinced that, say, starting several different branch runs from the room closest to the panel will result in less wire used overall.
I know this is a point of contention with those who feel strongly about the use of 2-wire circuits, but 3 and 4-wire ciruits are a savings in wire in themselves.
I try to maximize the use of them, and shed conductors of the circuit at nearest opprotunity, or best suitable location. Like some circuits are just stanard in method now. GB/DW is a 3-wire to a box under the sink. Kitchen Counters = another 3-wire, GFI the start of each. Baths are the same.... 3-wire for vanity recept GFI, and another appropriate 20A on the other.
Mark Heller "Well - I oughta....." -Jackie Gleason
Re: Conserving wire?#48491 02/14/0502:23 AM02/14/0502:23 AM
I also run a ton of three wire. My panel looks verrry pretty. It has alternating colors red-black-red-black. The only sitiuation is for GFI breakers and arc faults. Which brings up a ? I heard from a fellow electrician that you could share a nuetral with arc's. I told him that I never heard that before and went on my way.
What do you guys think about multiple sub panels? Are they cost effective? What size subs do you run for $4k sq/ft homes?
Re: Conserving wire?#48492 02/14/0507:51 AM02/14/0507:51 AM
I also use multi-wire ckts. as needed. But I am trying to reason through whether or not wire is saved by by the method described above. At first thought, it appears so. But the more I think about I don't believe so.
Re: Conserving wire?#48493 02/14/0509:02 AM02/14/0509:02 AM
210.4 says that when a multiwire circuit supplies the same yoke that it needs to be on a 2 pole breaker. My question is say with the 2 SA branch circuits do you put them on a 2 pole breaker just to be safe? It also seems that if somebody else at a later time goes to work on the panel, that they may notice quicker that the are mulitwire circuits in the panel and know not to start rearanging the circuits without thinking about the phasing first.
Thats how we do it up in the woods!
Re: Conserving wire?#48494 02/14/0509:11 AM02/14/0509:11 AM
if i remember right our inspector allows us to put them on single pole breakers as long as the breakers are on the same phase, so there's no possibility of 240v through a short to a device
I hope you are not remembering correctly.
Each leg of a multiwire branch circuit must be connected to different buses in the panel.
Any other way can result in overloading the neutral.
Branch Circuit, Multiwire. A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.
In order for the ungrounded conductors to have a 'voltage between them' they must be on opposite panel busses.
[This message has been edited by iwire (edited 02-14-2005).]
Bob Badger Construction & Maintenance Electrician Massachusetts
Re: Conserving wire?#48496 02/14/0509:35 AM02/14/0509:35 AM
detubbs, dude you are scaring me. First off Bob pointed out the danger. Second your inspector should go back to school or give up inspecting. Third do you always let the inspector instruct you (incorrectly) on how to do your work? Now for the original question. I din't see a meaningfull savings of wire in the average home. One way or another all the outlets on the circuit have to get wired together. I don't see how starting here vs there makes a difference.