Compressed CU Conductors for 1000A service?

[Lbartowski]

I'm trying to determine if I can get 1000 amp service into (2) existing 4" PVC conduits.

The tables in annex C or show the max number of conductors allowed in conduits for standard stranded copper (concentric) or compact aluminum. I'm being told they make "compressed" CU, which is different than standard CU or compact AL.

The way I figure it, I'd need to be able to fit (4) #400 MCM (compressed) CU conductors in each 4" to make it work.

 

[Lbartowski]

Because #400MCM CU is rated at 325A x 4 conductors = 1340amps x 80% derating factor gives me 1072 amps.

 

[electrofelon]

I am not sure why are you are getting that you need compressed copper, it looks like regular THHN will work with 8 conductors in a 4 inch PVC.

If you do need more room, other strategies are go up to three sets per conduit (will get you more room even though you would have a .70 derating factor). You could also consider a reduced neutral.

 

[electrofelon]

By the way it appeared you didn't derate from the 90 degree column. even 300 MCM will work.

 

[Lbartowski]

Good call, thank you. I was in the wrong table and using the wrong column.

They should still add a table for conduit fill for compressed CU, but you're right, it doesn't apply here!

 

[infinity]

Also given that standard conductors are readily available and would work I wouldn't even consider something like a compressed conductor. I agree with electro, just go with regular old 300 kcmil.

 

[winnie]

IMHO a table would not be of much help.

If you are in such a tight corner that you need compressed or compact Cu, then you are probably also doing things like using reduced neutral, bare EGC, etc. So you would need to calculate for different conductor sizes.

On top of this different manufacturers have similar but not exactly the same conductor diameters, and if things are this tight you should be using the conductor diameter supplied by the manufacturer.

Finally, if you are in a really tight corner, you can probably get compressed _segmented_ conductors. Though you'd probably paying so much for the custom cable that you might as well just bite the bullet and get larger conduit installed.

-Jon

 

[Terminator5047]

Good luck pulling compressed wire around any kind of offset or 90 even with a 10k