2 sets of conductors (3-wire + ground), one is copper and the other is aluminum.

[Magic Gorge]

During a recent survey, we discovered that these 2 sets of 500kcmil conductors were different metal types, I was wondering if this is allowable by the NEC.

 

[chris kennedy]

During a recent survey, we discovered that these 2 sets of 500kcmil conductors were different metal types, I was wondering if this is allowable by the NEC.

Are they connected in parallel?

 

[Magic Gorge]

Are they connected in parallel?

Yes, though only 1 is necessary for the 400A branch breaker it is fed from.

 

[iwire]

Yes, though only 1 is necessary for the 400A branch breaker it is fed from.

If say phase A has one aluminum conductor and one copper conductor it is a violation.

One the other hand if phase A is all copper and phase B is all aluminum that would be fine assuming correct sizing.

 

[Magic Gorge]

If say phase A has one aluminum conductor and one copper conductor it is a violation.

One the other hand if phase A is all copper and phase B is all aluminum that would be fine assuming correct sizing.

Yes, that is the case, each phase is one type. Thank you.

 

[Magic Gorge]

If say phase A has one aluminum conductor and one copper conductor it is a violation.

One the other hand if phase A is all copper and phase B is all aluminum that would be fine assuming correct sizing.

Do you have an NEC rule for reference?

 

[chris kennedy]

310.10(H)(2)(2)