2 computer circuits sharing a neutral

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aftershock

aftershock

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Location
Memphis, TN
Im gonna bid a job wiring 2 computer circuits. Im not a big fan of computer circuits sharing a neutral.
What do you folks think?
Do they make a #12 mc cable with 2 hots 2 neutrals and a ground?
Should I just run 12/3 mc?

I know I could use a 12/4 mc and tape the blue wire white, but that is a code violation.
 
They do make an MC cable with 2 hots and 2 neutrals.

You could also run 2 12/2 MC cables. One for each circuit.

Chris
 
How about a multi-wire then? With single phase will reduce voltage drop on the grounded conductor circuit which is a good thing.
 
480sparky said:
Use the 12-2-2 MC.
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I called our supply house and they do not stock it. After speaking with my boss, it looks like we will go with 12/3.

Seems the supply houses are not stocking much recently. Even if they could order it, we are so low on work my boss wants to get this estimate out rather quick.
 
Unless my client insists on separate neutrals (and some do precisely that), I commonly design office environments with common neutrals. A 12/3 MC should be fine.
 
Thanx for all the replies. I was mainly more curious as to what you folks would do in this situation.

Being as 12-2-2 is not readily available where I am 12/3 will do.
I have seen what a broken neutral can do when shared by more than 1 hot.

Anyone got a link to a site which supplies 12-2-2?
 
dereckbc said:
How about a multi-wire then? With single phase will reduce voltage drop on the grounded conductor circuit which is a good thing.
Click to expand...

Could you explain this statement a little better please? I don't see what the difference would be whether it is single phase or 3 phase. I also don't see where voltage drop plays into this any different than it would any other ordinary application.

He could still share a neutral even if it's 3 phase as long as the 2 circuits are landed on seperate phases.
 
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steelersman said:
Could you explain this statement a little better please? I don't see what the difference would be whether it is single phase or 3 phase. I also don't see where voltage drop plays into this any different than it would any other ordinary application.

He could still share a neutral even if it's 3 phase as long as the 2 circuits are landed on seperate phases.
Click to expand...


With seperate neutrals, you have the full length of both the hot and neutral on both circuits. With a shared neutral, you have only one length of the neutral.

Someone posted an image showing it. Maybe they'll repost it here.
 
steelersman said:
Could you explain this statement a little better please? I don't see what the difference would be whether it is single phase or 3 phase. I also don't see where voltage drop plays into this any different than it would any other ordinary application.
Click to expand...

Anytime you use a multiwire branch circuit you can reduce voltage drop. (Assuming same loads, same size condutors, same length etc.)

From a long ago thread
roger said:
Here is an illustration from Ed MacLarren that will help visualisation.

Ed's3wireverses2wire.gif


Roger
Click to expand...
 
iwire said:
Anytime you use a multiwire branch circuit you can reduce voltage drop. (Assuming same loads, same size condutors, same length etc.)From a long ago thread
Click to expand...


Ok this is something new to me. I now can understand this concept, however, what dereckbc said makes it sound like you will only reduce the voltage drop if you use the shared neutral on single phase. I don't see how this would make any difference. Another words this concept should also work on 3 phase just the same.
 
steelersman said:
however, what dereckbc said makes it sound like you will only reduce the voltage drop if you use the shared neutral on single phase. I don't see how this would make any difference. Another words this concept should also work on 3 phase just the same.
Click to expand...


I am not sure what he was driving at, I will not try to guess. I am sure he will get back to us. :smile:
 
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