Service size

[Leonan]

Hi everyone, I did a 400A service in MA and the inspector asked to use 800kcmil aluminum wire, but in code 310.12 I can use 600cmil. Am I right?

 

[augie47]

120/240 single phase service ??
If so, 600 kcmil

 

[infinity]

If not for a dwelling you can use 750 kcmil AL if the calculated load is 385 or less.

 

[Leonan]

120/240 single phase service ??
If so, 600 kcmil

Yes. 120/240 single phase, a dwelling.

 

[infinity]

Yes. 120/240 single phase, a dwelling.

Then you'll need a minimum conductor rated at 83% of 400 amps.

 

[zbang]

Does anyone sell or use 800kcmil (it's in the size charts)? I don't think I've ever seen larger than 750, get larger than that and it smaller sizes doubled.

 

[infinity]

Does anyone sell or use 800kcmil (it's in the size charts)? I don't think I've ever seen larger than 750, get larger than that and it smaller sizes doubled.

Almost 40 years never installed anything larger than 750 kcmil.

 

[Elect117]

Parallel runs of 4/0 aluminum work * As long as the load is less than 360A *. 250kcmil Al in parallel if the guy is just looking for you to have more than 400A of conductor (which is not required).

Or

Parallel 3/0 Cu.

Saying 800kcmil is wild because that is technically still less than 400A. So I don't exactly understand his point. Unless you have a load or line side tapped power system that requires it to be larger than 360A but less than 400A.

You are allowed to use the round up rule in 240 as long as the conductor ampacity is larger than the load.

 

[Leonan]

Almost 40 years never installed anything larger than 750 kcmil.

I've never seen that either. I just wanted to make sure I'm covered by nec 310.12 because I used a 600 cmil aluminum

 

[Leonan]

Parallel runs of 4/0 aluminum work * As long as the load is less than 360A *. 250kcmil Al in parallel if the guy is just looking for you to have more than 400A of conductor (which is not required).

Or

Parallel 3/0 Cu.

Saying 800kcmil is wild because that is technically still less than 400A. So I don't exactly understand his point. Unless you have a load or line side tapped power system that requires it to be larger than 360A but less than 400A.

You are allowed to use the round up rule in 240 as long as the conductor ampacity is larger than the load.

 

[Leonan]

My load is 260A I used 600kcmil aluminum based on 310.12

 

[roger]

Or

Parallel 3/0 Cu.