250.122(B) or not?

[pete m.]

Looking for opinions...

If a person chose to use 4awg copper conductors for a 60 amp circuit would 250.122(B) apply if the reason for using the 4awg was based on 110.14(C)(1)(a) and 60 degree terminations?

Thanks,

Pete

 

[infinity]

You mean sizing the EGC for something like this:

 

[augie47]

My opinion would be you would not need to increase the size of the EGC in that case since the #4 is the required conductor by 110.14 under certain conditions

 

[pete m.]

Thats exactly what I'm referring to Rob. Thanks for the graphic!

Pete

 

[infinity]

Here's an old thread where a similar installation was discussed with some detail:

http://forums.mikeholt.com/showthread.php?t=108690

 

[pete m.]

My opinion would be you would not need to increase the size of the EGC in that case since the #4 is the required conductor by 110.14 under certain conditions

If, on the inspection, you found that the terminations were rated up to 75 degrees would it then be an issue with 250.122?

Pete

 

[pete m.]

Here's an old thread where a similar installation was discussed with some detail:

http://forums.mikeholt.com/showthread.php?t=108690

Thanks for the link... In the example you gave (using the 6awg due to the lug limitations) even if you used an 8 inch piece of #6 and then spliced #12 to it to complete the circuit back to the panel I could see an argument being made that 250.122(B) would apply. I could also see a successful argument to not apply 250.122(B) for the same application.

I guess it all actually boils down to 250.4(A)(5)

Pete

 

[augie47]

If, on the inspection, you found that the terminations were rated up to 75 degrees would it then be an issue with 250.122?

Pete

can I not look ? :grin:
If both ends of the cable were terminated on devices rated at 75?, then I would have to say you woukd need to follow 250.122

 

[infinity]

This is one of the more poorly written code sections. IMO it's almost impossible to draft this section so that every particular scenario can be accounted for. For me a simple solution would be to say that 250.122(B) does not apply when the raceway is a listed EGC. That would pretty much eliminate many of the problems associated with up-sizing the EGC.

 

[don_resqcapt19]

This is one of the more poorly written code sections. IMO it's almost impossible to draft this section so that every particular scenario can be accounted for. For me a simple solution would be to say that 250.122(B) does not apply when the raceway is a listed EGC. That would pretty much eliminate many of the problems associated with up-sizing the EGC.

I think they could get rid of the problem completely with a new Table 250.122 that based the size of the EGC on the size of the ungrounded conductors...just like is done in T 250.66.

 

[Volta]

I think they could get rid of the problem completely with a new Table 250.122 that based the size of the EGC on the size of the ungrounded conductors...just like is done in T 250.66.

Thank you.