Underground 400 amp service sizing

[Stevenfyeager]

Code requires #600 AL for 400 amp residential service but none of the Elec supply stores seem to carry it. Only up to 500. Frustrating. I usually just run two parallel 4/0 AL runs. What do you do? Thank you.

 

[peter d]

I would run two conduits in parallel.

 

[ptonsparky]

I would prefer the two runs.

 

[Cow]

I've never tried to get 600 AL, I can get 750 AL easily though. But, like the others mentioned I'd probably just parallel it.

 

[shortcircuit2]

Code requires the services conductors to be sized for the calculated load.

If your installing a "400-amp" service with multiple switches, size the conductors to the load calculation.

If your installing a "400-amp" service with a single 400-amp switch then size for the rating of the switch (400-amp).

I install underground "400-amp" services with a 320-amp meter socket fed by 2-sets of 4/0 URD, then put two 200-amp main breaker panels grouped in the dwelling. Is it really a 400-amp service? No, it is a service with two 200-amp switches with a rating capacity of that of the 2 sets of 4/0 URD...depending if it is in the same conduit or separate conduits. It is generally referred to as a "400-amp" service though.