# Circuits for cubicle farm



## 480sparky (Sep 20, 2007)

BrightLight said:


> .............Six current carrying conductors requires a 20% derating, 12 ga thhn with 90 degree insulation derates to 24 amps, so the hots should hold up ok, but what can I expect on the 10 ga neutrals that are going to return the current from two three phase circuits each? Will they hold up?


 
No need for a 10 neutral. 12 is just fine.

And it's the _grounding conductor_, not chassis ground. Keep the automotive terms in the garage.


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## BrightLight (Jun 24, 2009)

*Chassis ground*

Yeah, I was just looking for a way to distinguish the ground that bonds the chassis of the cubicles from the iso ground that serves the computers.

I have always preferred a #10 neutral, in fact the whip that is part of the cubicle system has four #12 hots and two #10 neutrals. I'm thinking the manufacturer knows something.

It is my understanding that computer loads in a three phase environment can create a harmonic that drives a current higher than that protected on the hots, possibly as much as twice the current as might be found on the hots. Hence the #10.

Now I am thinking about a neutral returning the current from two circuits in a three phase enviroment feeding computers, and I am wondering if I could conceivably cook a neutral and over volt a mess of computers and go bankrupt paying for the damage.


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## jbfan (Jan 22, 2007)

Sounds lie Herman Miller cubes. 
All the cubes we have have the upsized neutrals. Most of the time I feed them with mc cable with a #12, and so far never had a prblem.

Are yoiu deriving the 4th circuit from the same panel?
We tried that and relized it was a waste of time and money, as the people in the cubes wired anything anywhere they saw an open receptacle.

I run up to 10 cubes per boat, but all of our cubes are now 6x6 and people can not havbe as many devices as before, so no problems with overloads.


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## BrightLight (Jun 24, 2009)

jbfan said:


> "Sounds lie Herman Miller cubes.
> 
> I feed them with mc cable with a #12,
> 
> ...


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## pjg (Nov 11, 2008)

you might want to look at art. 605.


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## McClary’s Electrical (Feb 21, 2009)

You ever heard of a super neutral?,,,,,that's why there's two tens in the office manufactured wiring. I've been through this, you don't want to run a #12 neutral


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## Bob Badger (Apr 19, 2009)

BrightLight said:


> I think I am going to bring him four runs of conduit in the ceiling, with four circuits each. Black, red, blue, pink, (the color code in the whip from the cubicles) with two 10ga neutrals, and an isolated ground, allowing the conduit to be the chassis ground.


We would just run MC cable this.

We generally use AFC home run cable for this and I bet some equivalent is available in your area.

You can get it with conductors that match the furniture whips.


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## BrightLight (Jun 24, 2009)

mcclary's electrical said:


> You ever heard of a super neutral?,,,,,that's why there's two tens in the office manufactured wiring. I've been through this, you don't want to run a #12 neutral


No, I really don't. 

Yes, I am aware of a "super" neutral, although I have never heard it so named. I've read articles about third harmonics and having seen what can happen when a common neutral gets dropped, I would very much not like to be responsible for such a melt down.


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## BrightLight (Jun 24, 2009)

Bob Badger said:


> We would just run MC cable this.
> 
> We generally use AFC home run cable for this and I bet some equivalent is available in your area.
> 
> You can get it with conductors that match the furniture whips.



That's a good tip. I hate to think what the price differential is on 250' of 12-4/10-2 and just pulling into some 3/4" flex would be. Flex and individual wires costs $1.08 before taxes. The savings on pulling time and effort would be worth? another ten cents per foot? Were I wiring from scratch I certainly would want to use this stuff.

I'll see if I can find it. Thanks.


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## BrightLight (Jun 24, 2009)

Bob Badger said:


> We would just run MC cable this.
> 
> We generally use AFC home run cable for this and I bet some equivalent is available in your area.
> 
> You can get it with conductors that match the furniture whips.



Hmmmm. I can get a 250' coil for $340. That is $1.36/ft or 15 cents per foot more than flex and conductors. I almost certainly need more than 250', but the building engineer probably would prefer that I work in thin wall in the electrical closet anyway, so this may be just the ticket!

Thanks Bob, if I get the contract, I'll definitely be using this stuff.


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