Exceeding HVAC 600 volt 40 amp Breaker Rating.

[powerplay]

Hello,

I have an 600 volt HVAC that says the maximum Breaker is 40 amps. I have someone that has an good deal on an 600 volt 45 amp Breaker that tells me there should be no problem. The cable can handle the larger Breaker but are there other issues it may cause? I was thinking it is mostly an motor which should be ok with the "next breaker size up"?

Thank you very much for your feedback!

 

[texie]

Hello,

I have an 600 volt HVAC that says the maximum Breaker is 40 amps. I have someone that has an good deal on an 600 volt 45 amp Breaker that tells me there should be no problem. The cable can handle the larger Breaker but are there other issues it may cause? I was thinking it is mostly an motor which should be ok with the "next breaker size up"?

Thank you very much for your feedback!

If the data plate indicates a max breaker of 40 amps that is just what it says. It would be a violation the UL standards and the NEC to use a 45 amp breaker.

Edit to add: since you mention 600 volt maybe you are in Canada? I think the same UL standards apply and the Canadian code would be the same.

 

[hillbilly1]

You could always use a fuseable disconnect at the unit, but that would probably negate your savings on the breaker, unless you already have a fusible disconnect.

 

[powerplay]

If the data plate indicates a max breaker of 40 amps that is just what it says. It would be a violation the UL standards and the NEC to use a 45 amp breaker.

Edit to add: since you mention 600 volt maybe you are in Canada? I think the same UL standards apply and the Canadian code would be the same.

Yes it is an CEC application.
I was curious if it had to do with fault current or some other issue as the cable is protected by the Breaker, and I thought an Motor Load would short out once it exceeds it's max ampacity. Depending on the Motor we can go 150- 250% of FLA on an Circuit Breaker, but HVAC has more controls that shouod not be drawing more than it's rating either.

I am in the process of finding the proper 40 amp Breaker.

Thanks for the Feedback!

 

[Jraef]

The MOCP (Max. Over Current Protection) rating is a value derived from multiple factors all based on what is inside of the packaged HVAC unit. So yes, it's more than just the conductor protection, that's why it has that label.

 

[powerplay]

I was just considereing that an group of Motors can be fed from one Breaker as exceeding the FLA would eventually cause an short circuit from overheating, but realize that the HVAC has solid state controls etc.

I was curious if going to the next breaker size up would void warranty... If the breaker still respond to overcurrent, I was wondering what would be damaged from slightly more available current?

I have ordered the proper Breakers to ensure compliance and avoid complications, but it would be interesting to know what the Approval Sticker is based on and if the next size Breaker could cause issues... aside from an Inspector rejecting it.

Thank you!