Alum ser

[Oakey]

Ah yes 310.15 my bad. What is the breaker size for #2 for a sub feed?

 

[hmspe]

Ah yes 310.15 my bad. What is the breaker size for #2 for a sub feed?

Table 310-16. 75A for the 60C column. 90A for the 75C column. That's before temperature derate.

 

[wireman3736]

No. #2 al may only be protected at 100a when it's the main feeder, not a sub-feeder.

Ah, Another one of those code sections that is misused by many.

 

[Oakey]

I realize that 310.15(b)6 makes the rules for this size but pls bear with me here Im a little confused (doh!)..A #4 alum sub feed rated at 65 amps can be on a 70 breaker in the 75 column ...but a # 2 alum rated at 90 cannot be on a 100 breaker? Last question I promise LOL

 

[infinity]

I realize that 310.15(b)6 makes the rules for this size but pls bear with me here Im a little confused (doh!)..A #4 alum sub feed rated at 65 amps can be on a 70 breaker in the 75 column ...but a # 2 alum rated at 90 cannot be on a 100 breaker? Last question I promise LOL

Yes, because 65 amps does not correspond to a standard sized breaker listed in 240.6(A) you can go up to the next standard size of 70 amps. Since 90 amps is on the list no such rounding up is permitted.

 

[Oakey]

Thank you for the help.