Feeder Sizing

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ericstac

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Houston, TX
What would you say to run to a 1000 amp main from a transformer that's 160ft away?

This would be copper wire and fed underground. thanks
 
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If you're not worried about voltage drop 3 sets of 400kcmil copper gets you 1005 amps. Only two conduits complicates things.
 
If you're not worried about voltage drop 3 sets of 400kcmil copper gets you 1005 amps. Only two conduits complicates things.

thanks, sounds like my calculations.. and 3 of 500kcml would be 1140 amps, right?

The EE is trying to say it needs to be 3-400kcml in THREE 3" conduits..

EDIT: just noticed you said the two conduits complicates things?

damn. 3 sets = 9 wires? yeah that would complicate things. I was thinking 3 pairs.
 
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It is single phase and the transformer is pole mounted on the closest pole so there is no way of moving it. Sounds like the only way of doing this would be to add another conduit or change the main to 3ph huh..
 
What is the neutral load? If the calculated neutral load is 532 amps or less, you could put five 400kcmil in each of the 2 conduits. Four for the ungrounded conductors and one for the neutral. That gives you an ampacity of 1064 amps for the ungrounded conductors and 532 for the neutral.
 
Because it is underground, what configuration will the ducts be?

See Figure 310.60 for typical configurations and the associated tables or Figure B.310.15(B)(2)(2) and the associated tables depending on voltage.

If not a typical configuration, then get ready to do some calculations
 
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