service

[teco]

Hello, Can I use eight 500 kcmil T.H.W.N per phase for a 3000 amp 480/277 volt service or do I need to count the neutral as current carrying and increase to 600 kcmil?

Thanks

 

[bob]

Hello, Can I use eight 500 kcmil T.H.W.N per phase for a 3000 amp 480/277 volt service or do I need to count the neutral as current carrying and increase to 600 kcmil?

Thanks

Is this in an underground duct bank?

 

[raider1]

Take a look at 310.15(B)(4)

Chris

 

[teco]

No. It is eight 4" p.v.c. raceways and they are about 30' long.

 

[teco]

Hello, It is 310.15-4c that makes me think I need to go to 600 kcmil. I wasn't sure if I interpreted it right.

Thanks

 

[teco]

Is this in an underground duct bank?

No. It is eight 4"p v c raceways they are underground some of the way but they do travel on the building for about 15' Thanks.

 

[teco]

Take a look at 310.15(B)(4)

Chris

Thanks Chris. It is 310.15b4c that makes me think I needed to increase to 600 kcmil.

 

[infinity]

What type of load do you have? IMO it's really unlikely that a load would have more than 50% harmonic current, therefore the neutral is not a CCC.

 

[Joe Villani]

I agree with Trevor on this one. You should be to go.

However before installing these conduits, you might want to check with you AHJ requarding those conduits travelling 15' into the building without overcurrent protection. Some jurisdictions have very tight requirements with respect to 230.70 (A) (1). You might want to put them in the slab or cover them with at least 2" of concrete.



Joe Villani

 

[raider1]

Thanks Chris. It is 310.15b4c that makes me think I needed to increase to 600 kcmil.

Your welcome.

Does the load really consist of more than 50% non-linear?

I agree with Trevor and Joe, check the load to see if you really have that much non-linear harmonic loading.

Chris

 

[raider1]

By the way welcome to the forum.

Chris

 

[teco]

Thanks Joe. These conduits will be run from under a pad mount up a rear outside wall then along the wall for about 15'. They will enter the main breaker directly upon entering the building.

Thanks

 

[teco]

By the way welcome to the forum.

Chris

Thank You and thanks for the help.

 

[Dennis Alwon]

Thanks Joe. These conduits will be run from under a pad mount up a rear outside wall then along the wall for about 15'. They will enter the main breaker directly upon entering the building.

Thanks

Sounds like you are good to go.