Condensing unit

H

hhsting

Senior Member
Location
Glen bunie, md, us
Occupation
Junior plan reviewer
I have condensing unit MCA: 24.9A, MOCP: 30A. The condensing unit has fused disconnect with fuse size of 30A.

The engineer has provided 40A feeder breaker feeding the condensing unit fused disconnect. The engineer has provided #10 awg feeder cable s feeding the unit fused disconnect.

Should the feeder cables be #8 awg not #10 awg?
 
The conductors are required to be a minimum size of 24.9 amps. #12 THHN/THWN-2 in a raceway would be code compliant with the 30 amp OCPD. The feeder conductors are a different matter which is your question?
 
infinity said:
The conductors are required to be a minimum size of 24.9 amps. #12 THHN/THWN-2 in a raceway would be code compliant with the 30 amp OCPD. The feeder conductors are a different matter which is your question?
Click to expand...

My question is about feeder conductor size feeding the unit fused disconnect. Should it be #10 awg or #8 awg?


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hhsting said:
My question is about feeder conductor size feeding the unit fused disconnect. Should it be #10 awg or #8 awg?
Click to expand...
This has been debated here dozens of times. I don't think that anyone has come up with a clear answer. Can you protect the undersized feeder conductors at 40 amps when the MaxOCPD is 30 amps?
 
infinity said:
This has been debated here dozens of times. I don't think that anyone has come up with a clear answer. Can you protect the undersized feeder conductors at 40 amps when the MaxOCPD is 30 amps?
Click to expand...

Its condensing unit. It has fused disconnect fused at 30A integral. The feeder breaker feeding it is 40A. Enginner gave #10 awg because MCA is 24.9A.

I have no clue about feeder conductor should the feeder conductor size be based on MCA 24.9A or the 40A breaker?
 
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