Parallel conductors in same raceway...

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chevyx92

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VA BCH, VA
The way I read the code this is allowed although I have never seen it done before. I am now in a situation where I must achieve 3phase 480V 400A in (1) 4" Emt conduit. I would use 600 MCM CU but the boss says it costs too much and doesn't want to spend the money on it. So I propose to run (6) 300 AL and 1 ground in the conduit. We don't need a neutral as this is a sub-fed power panel and panel is loaded. (6) 300 AL would give me 408A ampacity which is what I need. My question is am I correct in only pulling the (1) ground in the conduit? The ungrounded conductors are parallelled and will be on a 400A breaker. I come up with a size of #1 AL based on table 250.122. Is this correct or do I need to parallel the ground as well??
 
the single #1 is sufficient.
as much as it pains me to say so, since money is an issuee and you are using EMT, the conduit can be your equipment ground
 
Keep in mind that for purpose of derating for temperature or number of conductors in a raceway, you can use the full temperature rating of the wire insulation.

-Jon
 
winnie said:
Keep in mind that for purpose of derating for temperature or number of conductors in a raceway, you can use the full temperature rating of the wire insulation.

-Jon
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Thanks and I have, that's why I selected 300 mcm AL which under the 90 degree column is good for 255A. So 255A X2 = 510A X .80 for the derating and you get 408A.
 
your boss cant be that that cheap alum is bad news no matter what anybody tells you run 1 set copper 500's youll earn your money that day
 
jrock0305 said:
. . . run 1 set copper 500's youll earn your money that day
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One set of 500 MCM Copper is only good for 380 amps. You can protect that size of conductor with a 400 amp breaker. But unless you can show, by calculation or other means, that the load is lower than 380 amps, you cannot use that size conductor. I think that is why the OP originally spoke of using 600 MCM Cu.
 
jrock0305 said:
your boss cant be that that cheap alum is bad news no matter what anybody tells you run 1 set copper 500's youll earn your money that day
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Who died and made you lord of the customers right to spend their money how they choose?

The fact is if the customer doesn't want to pay for copper, then aluminum is a fine alternative. Furthermore, your comment about aluminum conductors being "bad news" is idiotic at best and completely uninformed.
 
peter d said:
Who died and made you lord of the customers right to spend their money how they choose?

The fact is if the customer doesn't want to pay for copper, then aluminum is a fine alternative. Furthermore, your comment about aluminum conductors being "bad news" is idiotic at best and completely uninformed.
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I agree, well put.
 
peter d said:
Who died and made you lord of the customers right to spend their money how they choose?
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chevyx92 said:
I agree, well put.
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I do not agree. That was close to, if not actually beyond, the line between offering critical commentary and offering personal insults. Let?s not judge each other, shall we? And let's not be harsh, whether or not harshness appears to be called for.
 
charlie b said:

I do not agree. That was close to, if not actually beyond, the line between offering critical commentary and offering personal insults. Let?s not judge each other, shall we? And let's not be harsh, whether or not harshness appears to be called for.
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So you will allow someone elses opinion even if it holds no water what so ever and you will disagree with someone who is stating and disproving the other guy? You guys are the ones who try and make a false sense of security with this site by only allowing what YOU or what YOU think people want for answers. If he wants to lash out with idiotic remarks then he will get them back. Freedom of speech isn't just a one way street!
 
chevyx92 said:
So you will allow someone else’s opinion even if it holds no water what so ever. . . .
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Yes. I will allow anyone to express an opinion, even if it is clearly (to me, at least) wrong. Afterwards, I may or may not choose to post a contradictory opinion, or to simply state my disagreement.
chevyx92 said:
. . . and you will disagree with someone who is stating and disproving the other guy?
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What I disagreed with was that an insulting statement can be described as, “well put.”
chevyx92 said:
You guys are the ones who try and make a false sense of security with this site by only allowing what YOU or what YOU think people want for answers.
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This site is intended to provide a means for exchanging information and ideas. The moderators do not control what the members think, nor what they say. We will, however, intervene to prevent the use of rude or insulting language.
chevyx92 said:
If he wants to lash out with idiotic remarks then he will get them back.
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If he wishes to post idiotic remarks, we might not intervene to prevent whatever comments he gets back. If he wants to “lash out,” we might step in.
chevyx92 said:
Freedom of speech isn't just a one way street!
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Freedom of speech is not involved in this process. I can’t stop anyone from saying anything they want, nor would I want to have the authority to do so. But nothing in our set of laws (federal, state, local, or other) gives permission for anyone to say anything they want, at any time they want, and in any location they want, and in any tone of voice they want. You cannot, for example, use “freedom of speech” as justification for bursting into my kitchen at 3:00 in the morning and loudly shouting your opinions concerning the results of a recent election.

Well, this forum is Mike Holt’s house. He bought it, and he pays for its upkeep. He gets to set the rules for behavior. So if he says no cursing, and no rudeness, and no insults, and no non-professional behavior, which by the way he has said, then that’s how things are going to be. If you do not like these rules, then feel free to exercise your freedom of speech elsewhere.
 
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