CU TO AL

[Alwayslearningelec]

Engineer calls out for 4 #250 CU in 3" for 250A.
I come up with that #400 AL would be needed for same ampacity.
I also come up with that the conduit could remain the same size(3"). Make sense that conduit could remain 3" for #400Al? THanks

 

[Tulsa Electrician]

What is the feeder for.

 

[augie47]

From the Tables, it appears the 3" would have been larger than required for the 250s but the engineer may have been taking other factors into consideration such as the length of the run

 

[winnie]

Unless you are in a corner case for voltage drop, Al 350s are good for 250A.

-Jon

 

[infinity]

You could possibly use 300 kcmil aluminum (230 amps) and the next size up rule.

 

[electrofelon]

Engineer calls out for 4 #250 CU in 3" for 250A.
I come up with that #400 AL would be needed for same ampacity

Remember aluminum is two sizes up for the same ampacity (or very very close). Only hard part is remembering what the sizes are for some of the KCMIL sizes

 

[don_resqcapt19]

This is not a change that a contractor can make without the approval of the engineer. Some do not permit the use of aluminum on their projects.

 

[David Castor]

If this work was contracted under a bid process, the owner has essentially already paid for the specified copper wiring and the 3" conduit. You would have to submit a change order request and indicate the reason for the change and cost difference.

 

[Alwayslearningelec]

What is the feeder for.

Panel to panel

 

[infinity]

Panel to panel

Are you asking about switching to aluminum for value engineering purposes?