400 overhead riser

[wire monk]

400 amp overhead service what is the proper wire size for the riser in a piece of 3" EMT. Copper

 

[augie47]

lot of varibles.....
residential, commercial, 120/240 volt or other ?, temperature...

 

[davidaengelhart]

400 amp overhead service what is the proper wire size for the riser in a piece of 3" EMT. Copper

At least 500CU as long as the load is no greater than 380 amps commercially using a 75 or 90C conductors and sunlight resistant. #400 for a dwelling unit as applicable to 310.15(B)(6) '05NEC, in its entirety.

 

[wire monk]

Commercial 120/240

 

[480sparky]

Commercial 120/240

Single phase?

 

[augie47]

Commercial 120/240

sorry, in detail that might even lead to additional questions.,.,., but assuming 240/120 single phase with no ambient problems.
We now need to consider load. As David referenced, if the calculated load is 380 amps or less, then 310.16 & 240.2(B) would allow a 500 kcmil Cu
for the phase conductors with a neutral sized per 220.61 but not smaller than 1/0 per 250.24(C)