Parallel conductors

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Robert02857

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What size parallel conductors (in copper & aluminum) would be needed to feed a 400 amp load center at 277-480 volts. These conductors would be fed by the 400 amp I line breaker, would be 400 feet in length, at an ambient temperature of 96-104 degrees.

What size conductors (in Copper and Aluminum) would be needed to feed a 400 amp load center at 277-480 volts. These conductors would be fed by a 400 amp I line breaker, would be 400 feet in length, at a ambient temperature of 96-104 degrees.

Thanks,
Bob
 
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iwire

iwire

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infinity said:
Even at 400' in length? IMO larger conductors and less conduit would be cheaper.
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I have run the numbers a few times, and if you are using copper and if the installation of the conduit is fairly easy it is cheaper to use more runs. If the conduit is really easy to run, like across a roof it is much cheaper to run more sets.

I don't know how to put this correctly but the larger the conductor, the less current you can move per pound of copper.
 
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petersonra

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iwire said:
I have run the numbers a few times, and if you are using copper and if the installation of the conduit is fairly easy it is cheaper to use more runs. If the conduit is really easy to run, like across a roof it is much cheaper to run more sets.

I don't know how to put this correctly but the larger the conductor, the less current you can move per pound of copper.
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yep. copper is expensive. pipe is relatively cheap.

in any case, I pretty much use 1/0 for everything I can inside panels. It is small enough to bend fairly easily in MTW, and is the most cost effective way to get more than about 200A of ampacity in almost all cases.

sometimes I am trapped into using something bigger (like the 200 feet of 350MCM on my latest project), but 1/0 is my default for paralleling conductors. not real practical at 1200 or 1600A levels though.

the lugs are usually cheaper and easier to work with as well.
 
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iwire

iwire

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When I did my numbers I used 4/0 copper as the smallest size. 4/0 carries 200 amps and is still IMO very easy to work with.
 
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petersonra

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iwire said:
When I did my numbers I used 4/0 copper as the smallest size. 4/0 carries 200 amps and is still IMO very easy to work with.
Click to expand...

It probably varies by what your wire and labor cost is, and what you are used to doing. I don't have any pipe cost to worry about at all for the most part, so how many runs I have to make is not normally a consideration.
 
kwired

kwired

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How easy is it to find 400 amp equipment that will accept 3 conductors per line? Most of what I see has lugs designed for single 600's or two 250's or something very close to that anyway, never designed for 3 conductors though.
 
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petersonra

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kwired said:
How easy is it to find 400 amp equipment that will accept 3 conductors per line? Most of what I see has lugs designed for single 600's or two 250's or something very close to that anyway, never designed for 3 conductors though.
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two lugs on top and one on the bottom?

it may be impractical in some cases even with the lower cost in copper.
 
don_resqcapt19

don_resqcapt19

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kwired said:
How easy is it to find 400 amp equipment that will accept 3 conductors per line? Most of what I see has lugs designed for single 600's or two 250's or something very close to that anyway, never designed for 3 conductors though.
Click to expand...
While most equipment with a 400 amp rating does not come with lugs suitable for 3 conductors, a lot of it has optional lug kits that you can buy to permit the use of 3 or 4 conductors.
 
don_resqcapt19

don_resqcapt19

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Take a look at the rules in Article 310 and tell us what size you think you need and we will go from there.
 
Dennis Alwon

Dennis Alwon

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I would use an online calculator to help out. Remember if the load is not 400 amps then you only need to plug the calculated load in the formula. Using the calculator will give a wire size smaller than what the code requires. In that case just use whatever T. 310.16 requires
 
iwire

iwire

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OK, I tried to merge the OPs two similar threads into one. For whatever reason it did not go right and I lost some posts.

I apologize to the OP for any inconvenience.
 
kwired

kwired

Electron manager
Location
NE Nebraska
don_resqcapt19 said:
While most equipment with a 400 amp rating does not come with lugs suitable for 3 conductors, a lot of it has optional lug kits that you can buy to permit the use of 3 or 4 conductors.
Click to expand...

And is it worth it vs using 2-3/0 conductors vs 3-1/0 conductors in most cases. Meter sockets and safety switches often you put in your own lugs, circuit breakers - the optional lug kit may cost enough to not be worth it, unless you are ordering a panelboard, breakers, and other accessories all together, otherwise stock items you will get honked hard on pricing - especially accessories.
 
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