Size Question

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RooKie12

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Question is can you run a #8 CU branch circuit to a non-fused A/C disconnect and the downsize the conductors in the A/C whip to 10AWG CU ?? I always thought you could not downsize the circuit at the end of the run. Just can't find a code reference saying so.
 
Max Fuse/Brk is 40A not sure what the min ampacity is. Let's say its 27.8 can you down size your wire like that at the end of a branch circuit ?
 
RooKie12 said:
Max Fuse/Brk is 40A not sure what the min ampacity is. Let's say its 27.8 can you down size your wire like that at the end of a branch circuit ?
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Sure esp. since the #10 is good for 27 amps. Did you run #8 for voltage drop and you are concerned about the #10at the end of the run being a problem. It doesn't matter where it is in the run.
 
The concern was later on someone could see a #8 in the panel thinking they could put a 50A brk on it but the end of the run is only 10awg
 
RooKie12 said:
The concern was later on someone could see a #8 in the panel thinking they could put a 50A brk on it but the end of the run is only 10awg
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It is not an issue. You could label it in the panel if that makes you feel better but anyone that changes the breaker should know better esp. if max OCPD is 40 amps. Also the 50 amp on the #10 probably wouldn't be a problem.
 
RooKie12 said:
Max Fuse/Brk is 40A not sure what the min ampacity is. Let's say its 27.8 can you down size your wire like that at the end of a branch circuit ?
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Keep in mind that A/C units have different requirements for overcurrent protection.

For an A/C unit the overcurrent protection device can't exceed that marked on the A/C unit nameplate and the conductors only need to be large enough to carry the minimum circuit ampacity.

So provided that the #10 has an ampacity greater than the minimum circuit ampacity marked on the A/C unit it would be OK.

Chris
 
RooKie12 said:
Question is can you run a #8 CU branch circuit to a non-fused A/C disconnect and the downsize the conductors in the A/C whip to 10AWG CU ?? I always thought you could not downsize the circuit at the end of the run. Just can't find a code reference saying so.
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Yes. Now tell me why you could not?
 
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