Mark…that’s exactly why I asked about that in the prior post. Even the US standards say as much (unless I’m reading it wrong):
Thanks, for your help. None the less there is some variables invloved regarding this particular issue. It appears, as per Canadian and US electricial code that the AMP rating for a 6 AWG Aluminum conductor can be between 40 and 75 AMPS depending on the type.
I believe, I made the right call as identifying conductor type was not readily accessible without shutting off breakers. Further investigation by a qualified electrician should be conducted and was. Unfortunately, the electrician was very unprofessional with his communication and service. I am going to recommend to my clients that they have this electrician provide them in writing that the conductor type is appropriate.
Now, if we get back to the InterNACHI courseware how do we state that 40 AMP breaker on a 6 AWG is appropriate? As in fact it is correct if it is type TW but incorrect if it is type R90. Maybe this should be noted in the courseware to help prevent this issue from arising again. As table 4 of the Canadian electrical code states variables in the columns.
Furthermore, the Carson Dunlop text I refered to earlier (6AWG for 60AMPS) was for service drop and service entrance (free air), my mistake. Carson Dunlop states on pg 45 of module 3 in the Electricial courseware that ALUM wire size should be 6 AWG for 40 AMPS (same as InterNACHI).
I sincerely appreciate and respect everyones help on this thread. Thanks Nick and all fellow InterNACHI inspectors. The electrician I talked to today was very ignorant and I plan on filing an official complaint with his company.
An AC unit can be on an undersized wire as long as the the wire is big enough to support minimuim ampacity on the AC unit’s data plate. As far as I know that only applies to AC units. I read that in “Electrcal Inspections Of Excisting Dwellings”, great book
There is no requirement for the use of the anti-oxidant paste. Good practice but not required.
Secondly the rules for sizing the wiring goes by a different sizing criteria. The nameplate will have the needed info on it. The wire is sized based on the minimum circuit ampacity. The breaker is sized based on the maximum overcurrent size.
Please review Article 440 so you do not needlessly cost the customer money because you wrote up something that is proper.
I agree with Jim. However, I do need to add that in some cases you get a disconnect that will indeed call for Anti-Oxident in the listings posted on the product. In that case the Anti-Oxident would be required as part of the listing requirement.
However as Jim Said in a previous post, Anti-Oxident is not a requirement by the NEC in itself but rather a guideline for use when specific conditions warrant the application and use of an Anti-Oxident per the condition or listing of equipment.
I am not aware of any panelboard that requires Anti-Oxident paste but as jim said and I agree it is good practice and I always did it in my installations.
P.S. In case anyone is wondering…I am on Vacation Today !!! 11/30/2009
Enjoy your vacation!!
Mark, you need to correct a typo in the above quote…
A 40 amp breaker is always allowed with any of the 6 gauge wire temperature ratings.