480v air condition feeder question

[Delect]

I have a 480v ac unit the has a nameplate with minimum circuit ampacity of 29.6 and a Max breaker size of 35a, My question is, I have an available 30a HACR breaker, do you think this will run properly with this breaker and 10 guage wire? and If not would I have to upsize the wire to 8 Ga. If I used the 35A breaker? There is a 10/4 MC run about 40' to the area with a 30A HACR breaker and just want to be able to reuse it if possible? Thanks

 

[jumper]

Assuming all terminations are 75 degree, #10 is good for both 30 and 35 amps.

You can try the 30 amp breaker, however it may not hold on start up because of inrush. I prefer to use the largest MOCP allowed, in your case a 35 amp breaker.

 

[infinity]

As Jumper stated you can use the 30 amp OCPD. Since you're within 5 amps of the maximum permitted in all likelihood will work just fine. Your #10 MC cable could be used up to a 35 amp MCA and even larger OCPD with 75? C terminations.

 

[Jraef]

MCA already includes the 125% factor(s), so 10AWG would be fine (assuming you have considered VD). The 35A MOCP issue is the MAXIMUM breaker, but anything smaller (that will hold in) will be acceptable. The risk however is yours, there is no way to tell for sure in advance if that particular breaker will hold in under the largest motor (usually the compressor) starting current.

Since it's already there and meets code, I would try it but explain in advance to the user that if it nuisance trips, you may have to come out again and up-size it.