Gutters/Conductor Fill

[TWGJ24]

Existing Condition
A 12"x12"x10' Trough. With (51) Current Carrying Conductors. None are a continious Load or lighting circuits.
Was Told max amperage could only be 9.

How I see to do this.
1) Article 110-14-C
2) Table 310.16 #12 THHN at 90 degree 30A
3) Article 366-22 20% fill
Equals 28.80 #12 is .0133
4) Table 310.15(B)(2)(A) Adjustment Factors.
5) Annex B Table 310.11 Adjustment Factors with Diveristy.
6) Which comes to 15A. Then able to go to the next breaker size being a 20A Breaker.


If I am wrong how do you go about this issue.

 

[don_resqcapt19]

Assuming a metal wireway see 376.22(B). Your derating factor is 35%. You can't use the "diversity factors" without engineering supervision.

 

[infinity]

If you had an adjusted ampacity of 15 amps then that would be the maximum size of the OCPD since it's a standard size. Also if those circuits contain multi-receptacles then you cannot use the next size up rule.