Junction wires in a Trough

[spencercagen]

How many 4/0 THHN can I fix in a 12x12x48 trough? What is the calculation for the trade size? This is going to be for a single family Mother/Daughter. 400 Amp single phase, 2 meter/Disconnects. Getting spliced in the trough. Is this allowed

 

[LarryFine]

The limit is 40% fill in cross-section area; you'll never get near it.

Yes, splicing is permitted.

 

[don_resqcapt19]

If you are using power distribution blocks for the splices take a look at 376.56(B)(1) if you are under the 2017 or 2020 codes.