code requirements for romex leaving subpanel

[Matt Marsh]

It should also be mentioned that if the length of this raceway exeeds 24 inches, you must derate the ampacity of each conductor by a factor given in NEC table 310.15(B)(3)(a). As an example, where NM is installed, this would start causing problems with #12s at five 2 conductor cables (over 9 current carrying conductors), or with #10s at three 2 conductor cables (over 6 current carrying conductors). At 10 current carrying conductors, a #12 would need to be derated to 50% of 30 amps (15 amps), as per 90C column of 310.15(B)(16). At 7 current carrying conductors, the ampacity of a #10 must be derated to 70% of 40 amps (28 amps), as per the 90C column of table 310.15(B)(16). You would then be in violation by installing the #12s on a 20 amp breaker, or the #10s on a 30 amp breaker.

[Scot wolf]

It should also be mentioned that if the length of this raceway exeeds 24 inches, you must derate the ampacity of each conductor by a factor given in NEC table 310.15(B)(3)(a). As an example, where NM is installed, this would start causing problems with #12s at five 2 conductor cables (over 9 current carrying conductors), or with #10s at three 2 conductor cables (over 6 current carrying conductors). At 10 current carrying conductors, a #12 would need to be derated to 50% of 30 amps (15 amps), as per 90C column of 310.15(B)(16). At 7 current carrying conductors, the ampacity of a #10 must be derated to 70% of 40 amps (28 amps), as per the 90C column of table 310.15(B)(16). You would then be in violation by installing the #12s on a 20 amp breaker, or the #10s on a 30 amp breaker.

I think I did bring it up in post #3

[Matt Marsh]

Scot,

Why are you being so confrontational here? Do you feel threatened? Or what is the deal?

Because this is common practice where you live, doesn't make it the best way, nor does it make it code compliant. Steve pointed out the clamping requirements earlier in the post, and your reply to him implied that he was incorrect, when in fact his answer was more accurate than yours was. The exception to clamping that you alluded to only applies to surface mounted enclosures, and only after all the conditions of a through g are met.

[Randy Moore]

My Dad told me severals years ago about electricity this; PAY YOUR BILLS ON TIME AND DON'T MESS WITH IT, IT CAN KILL YOU.

[Matt Marsh]

My Dad told me severals years ago about electricity this; PAY YOUR BILLS ON TIME AND DON'T MESS WITH IT, IT CAN KILL YOU.

Where is that "LIKE" button LOL.

[Scot wolf]

Scot,

Why are you being so confrontational here? Do you feel threatened? Or what is the deal?

Because this is common practice where you live, doesn't make it the best way, nor does it make it code compliant. Steve pointed out the clamping requirements earlier in the post, and your reply to him implied that he was incorrect, when in fact his answer was more accurate than yours was. The exception to clamping that you alluded to only applies to surface mounted enclosures, and only after all the conditions of a through g are met.

Sorry, I didn't mean to come across as confrontational at all. As I posted above, it would be a good idea to check with his AHJ.