LuminousElectric
New member
- Location
- Wayne, New Jersey
got fail inspection today for running 10/2 Romex wire on 45 amp breaker.
name plate call for 27.7 amp min circuit amp and 45 amp Max over current protection
Welcome again.
In other words, you're correct, and the inspector is wrong. You've met both of the parameters specified on the equipment label.
When he mentions Art. 240.4 or 240.4(D) or 240.4(D)(7), you counter (politely) with "read 240.4(D) again and then see 240.4(G)."
I have been reviewing this same matter over the past few days also referring to an AC unit.. I have read where 240.4(G) refers to 440 parts 3 & 4.. I have read completely threw 440 3 & 4, but could not find the "Specific Permission" to allow the 240.4(D)"small conductor", in this case, #10 for breaker over 30amps.. please name where this "Specific Permission" is within this section, and also, have you had experience with this issue before where an engineer or code specialist had confirmed the matter for you? thank you for your knowledge..
I have been reviewing this same matter over the past few days also referring to an AC unit.. I have read where 240.4(G) refers to 440 parts 3 & 4.. I have read completely threw 440 3 & 4, but could not find the "Specific Permission" to allow the 240.4(D)"small conductor", in this case, #10 for breaker over 30amps.. please name where this "Specific Permission" is within this section, and also, have you had experience with this issue before where an engineer or code specialist had confirmed the matter for you? thank you for your knowledge..
It's not specifically called a special permission, but it's allowed by not being prohibited. The breaker is allowed to be large enough to carry starting current.I have read completely threw 440 3 & 4, but could not find the "Specific Permission" to allow the 240.4(D)"small conductor", in this case, #10 for breaker over 30amps.
Sorry, but I seem to be a little dense in following the responses you received on this topic. The nameplate rating states that the minimum OC protection is 27.7 amps but you're protecting it at 45 amps. Irrespective of what other Code sections might state Table 310.15(B)(16) does not allow you to protect # 10 wiring with a 45 amp breaker. This is an AC unit that will probably run for hours at a time. In my mind I would think that the insulation on the # 10 wiring would be severely taxed. Could someone please explain why # 8 would not be required ?got fail inspection today for running 10/2 Romex wire on 45 amp breaker.
name plate call for 27.7 amp min circuit amp and 45 amp Max over current protection
Sorry, but I seem to be a little dense in following the responses you received on this topic. The nameplate rating states that the minimum OC protection is 27.7 amps but you're protecting it at 45 amps. Irrespective of what other Code sections might state Table 310.15(B)(16) does not allow you to protect # 10 wiring with a 45 amp breaker. This is an AC unit that will probably run for hours at a time. In my mind I would think that the insulation on the # 10 wiring would be severely taxed. Could someone please explain why # 8 would not be required ?
Bear in mind the OP is in NJ and still on the 2014 NEC if that has any bearing.
Why couldn't that have been the answer from the start ?440.22 Application and Selection.
(A) Rating or Setting for Individual Motor-Compressor. The motor-compressor branch-circuit short-circuit and ground-fault protective device shall be capable of carrying the starting current of the motor. A protective device having a rating or setting not exceeding 175 percent of the motor-compressor rated-load current or branch-circuit selection current, whichever is greater, shall be permitted, provided that, where the protection specified is not sufficient for the starting current of the motor, the rating or setting shall be permitted to be increased but shall not exceed 225 percent of the motor rated load current or branch-circuit selection current, whichever is greater.
Exception: The rating of the branch-circuit short-circuit and ground-fault protective device shall not be required to be less than 15 amperes.
Thanks Augie & Dennis. The NEC is funny like that. For years you come to rely on table 310.16 for wire amp ratings. Then they change the table # to 310.15(B) and you have to get used to that. Then you have to take into consideration how other sections might modify that table's guidelines. Why can't they make it simple?
Anyway, I think this section sums it up :
Why couldn't that have been the answer from the start ?
If we're considering the cooling fan motor, isn't the condenser motor the largest load which ends up dumping you back to 440.22(A)? If not, what would the correct answer have been if not the section I cited ?Don't AC units typically have two motors?
Why couldn't that have been the answer from the start ?
Table 310.16 might have a different name today, but is still same table with only minor changes. All it is is minimum ampacity of conductors (per insulation temp rating) and at an ambient of 30 degrees C. Overcurrent protection starts in art 240, general rules require conductors to be protected at no more then their ampacity, but then there is other sections that modify those general rules for specific applications, air conditioning and refrigeration equipment is one of those other sections.Thanks Augie & Dennis. The NEC is funny like that. For years you come to rely on table 310.16 for wire amp ratings. Then they change the table # to 310.15(B) and you have to get used to that. Then you have to take into consideration how other sections might modify that table's guidelines. Why can't they make it simple?