Sharing a grounded conductor between two circuits

[jxofaltrds]

Re: Sharing a grounded conductor between two circuits

?This was mainly asked concerning a single-phase residential install, but it could have applications elsewhere?


?Since there is no voltage between the two ungrounded conductors in this arrangement,?

100 ?ungrounded conductors that HAVE a voltage between them?

Mike P.

 

[monkey]

Re: Sharing a grounded conductor between two circuits

I happen to be working on a residential job where a scenario very similar to this exists. What happened was a Sqare D loadcenter was filled and someone needed more space for a 220 circuit. There were 2 multiwire circuits (20A), one for the kitchen, one for the living room. To free up space, both hot conductors on each of the circuits were placed on the same breaker(Square D), resulting in two hots on the same leg sharing a neutral, but both on the same breaker thus eliminating the possibility of overloading the neutral. (All conductors are #12). Besides the issue of the kitchen being shortchanged is there a code or safety issue here that I am not seeing?
Brian

[ June 27, 2003, 11:50 PM: Message edited by: monkey ]

 

[hurk27]

Re: Sharing a grounded conductor between two circuits

Monkey
YES and No
1. The placement of two wires under the screw of a single pole breaker can violate some manufacturs listing and lableing if there only listed for one wire per terminal.

2. The combining of the kitchen and living room circuits would violate 210.52 (B) (2)

(2) No Other Outlets. The two or more small-appliance branch circuits specified in 210.52(B)(1) shall have no other outlets.

Now if these two circuits were wired to a stacked or piggy back type breaker you will still have the problem of the neutral being over loaded.

 

[jason]

Re: Sharing a grounded conductor between two circuits

this is rather interesting, and i understand all points made... BUT, the original poster spoke about this being residential but could be used in other applications. I've personally never seen NM with 2 14's and a 10.............. what would it be called? 14/1 10/1 w/ground NM?

 

[don_resqcapt19]

Re: Sharing a grounded conductor between two circuits

jason,
In many areas, NM is not permitted for residential wiring. When using EMT, there is no problem installing different size conductors for the cirucit.
Don

 

[monkey]

Re: Sharing a grounded conductor between two circuits

Jason,
A while back someone posted a link on this site or another electrical site which showed a romex product with a "Super" neutral. It was designed for commercial use when wiring circuits with non-linear loads and it has an oversized neutral. I just can't find the link now. Hopefully someone will have it.
Brian