Shared Nuetral Per Spec

[mstrlucky74]

Never came across this before in electrical spec.
"Provide shared neutral conductor (1) standard wire size greater than the branch circuit phase conductor, for all branch circuits to receptacles(except GFI)"

I know we then have to provide a handle tie or multi pole breaker but the neutral being larger is a first for me. So if I'm running #12 branch I have to have a #10 neutral. Why do you think they are requesting this.

So if I'm running out a 6 ckt homerun with #10's my neutral has to be #8's. Interesting

 

[iwire]

It is a super neutral spec.

Kind of pointless but not uncommon in office buildings for feeds to modular furniture.

The idea is that non-linear loads run on multiwire branch circuits can create harmonic currents that multiply on the neutral. The larger neutral is thought needed to protect it from overloads.

Price it that way and move on.

 

[mstrlucky74]

It is a super neutral spec.

Kind of pointless but not uncommon in office buildings for feeds to modular furniture.

The idea is that non-linear loads run on multiwire branch circuits can create harmonic currents that multiply on the neutral. The larger neutral is thought needed to protect it from overloads.

Price it that way and move on.

I hear ya. Just wanted to know....as I always do. Don't like to just "put it in" unless I understand it. I read up on non-linear loads. Thanks!:thumbsup:

 

[augie47]

see it required and installed without requirement occasionally ... also occasionally see jobs where it would have been a good idea...
It is actually rare these days for me to see MWBC but that may just be a local thing

 

[infinity]

Never came across this before in electrical spec.
"Provide shared neutral conductor (1) standard wire size greater than the branch circuit phase conductor, for all branch circuits to receptacles(except GFI)"

I know we then have to provide a handle tie or multi pole breaker but the neutral being larger is a first for me. So if I'm running #12 branch I have to have a #10 neutral. Why do you think they are requesting this.

So if I'm running out a 6 ckt homerun with #10's my neutral has to be #8's. Interesting

Sounds like they want you to not use MWBC's.

 

[iwire]

Sounds like they want you to not use MWBC's.

:?:huh:

I read it the opposite way.

 

[infinity]

:?:huh:

I read it the opposite way.

The way I see it using super neutral MC cable possibly requires a special order many contractors would just rather use off the shelf MC and forget the MWBC with over sized neutral.

 

[iwire]

The way I see it using super neutral MC cable possibly requires a special order many contractors would just rather use off the shelf MC and forget the MWBC with over sized neutral.

If they did not want MWBCs the specs would just say that right?


As far as MC cable, in this area I can get super neutral cable the next day. I can't say how it is in NJ / NY.

 

[petersonra]

People put all kinds of goofy stuff in specs. Just do what they want and pocket the money.

I have probably mentioned this before because it's one of the goofiest things I ever ran across but at a previous employer we had an engineering company specify that all enclosures had to include a lug for a 2/0 ground cable. It looked pretty strange on the sheet-iron of the 4 x 6 junction boxes we supplied.

 

[mstrlucky74]

Could you just run the homeruns with the oversized neutral and then branch out with a regular sized neutral MC cable? I know it says otherwise but I'm wondering if this too would electrically satisfy what they are looking to accomplish?

 

[iwire]

Could you just run the homeruns with the oversized neutral and then branch out with a regular sized neutral MC cable? I know it says otherwise but I'm wondering if this too would electrically satisfy what they are looking to accomplish?

:huh:

You say you know what it says but you don't know if they mean what they wrote?:huh:

 

[JFletcher]

:huh:

You say you know what it says but you don't know if they mean what they wrote?:huh:

I think I see what he is asking: provide oversized neutral MWBC to point x, then split circuit (no longer mwbc at that point) from there using regular mc.

~~~~

sounds like an RFI is in order if you want to go that way.

 

[growler]

I know we then have to provide a handle tie or multi pole breaker but the neutral being larger is a ​first for me. So if I'm running #12 branch I have to have a #10 neutral. Why do you think they are requesting this.

It is a super neutral spec.

Kind of pointless but not uncommon in office buildings for feeds to modular furniture.

The idea is that non-linear loads run on multiwire branch circuits can create harmonic currents that multiply on the neutral. The larger neutral is thought needed to protect it from overloads.

Price it that way and move on.

The idea of the super neurtal spec is nothing new. This goes back to at least the late 80's.