a/c compressor wire size

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westelectric

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westchester county, NY
Heres what I have. Min cir amp=20, max fuse 35a, min fuse 30a, rla=15.4
Therefore 15.4x125=19.25a. Is the min cir amp the same as doing that calc? If yes, then #14 @60 deg. is good for 20a. My question is, is all this correct? Is it ok to run #14 and put on 30a c.b. for this single motor compressor (440.32). I think I'm ok doing this. Big savings from #10 to #14.
 
westelectric said:
Heres what I have. Min cir amp=20, max fuse 35a, min fuse 30a, rla=15.4
Therefore 15.4x125=19.25a. Is the min cir amp the same as doing that calc? If yes, then #14 @60 deg. is good for 20a. My question is, is all this correct? Is it ok to run #14 and put on 30a c.b. for this single motor compressor (440.32). I think I'm ok doing this. Big savings from #10 to #14.
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Yes it is. You got it correct. But that 20 only applies to certain situation. art. 240.4-- the asterik at the bottom of Table 310.15
 
westelectric said:
Heres what I have. Min cir amp=20, max fuse 35a, min fuse 30a, rla=15.4
Therefore 15.4x125=19.25a. Is the min cir amp the same as doing that calc? If yes, then #14 @60 deg. is good for 20a. My question is, is all this correct? Is it ok to run #14 and put on 30a c.b. for this single motor compressor (440.32). I think I'm ok doing this. Big savings from #10 to #14.
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is that what the nameplate is saying? if it is the 125% is already multiplied in the nameplate ratings. so i would say u need a #12awg with a 30a breaker
 
cloudymacleod said:
is that what the nameplate is saying? if it is the 125% is already multiplied in the nameplate ratings. so i would say u need a #12awg with a 30a breaker
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Why? 14 gauge is good for 20 amp.
 
Dennis Alwon said:
Why? 14 gauge is good for 20 amp.
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well i always perceived that the art 240-4(d) says for 14 awg it's rated for 15a, 12awg it's rated for 20a, and 10awg is rated for 30a, unless u r derating or using correction factors for ambiant temps. but i do see the a440-32 but i always thought the 125% is already calculated out for u on the nameplate rating, so u should have to not to do any calc's to that particuler nameplate info. i could be misreading 440-32 wrong.
 
cloudymacleod said:
well i always perceived that the art 240-4(d) says for 14 awg it's rated for 15a, 12awg it's rated for 20a, and 10awg is rated for 30a,
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240.4(D) does not apply here, 240.4(G) does.
 
You are correct the 125% is already in the namelate for the min. cir amps Art. 240.4(D) It says unless specified in 240.4(E) or (G).... (G) gives the except. for ac units
 
Dennis Alwon said:
You are correct the 125% is already in the namelate for the min. cir amps Art. 240.4(D) It says unless specified in 240.4(E) or (G).... (G) gives the except. for ac units
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ok, i didn't read further into a240-4(d), so basically it saying u can use the 60c column for a/c units.
 
cloudymacleod said:
ok, i didn't read further into a240-4(d), so basically it saying u can use the 60c column for a/c units.
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Not really-- it says you can use the 20 amp rating of #14 wire when used for a/c. I think that is what you meant. :D
 
Dennis Alwon said:
BTW I loved your response on the puck lights. :)
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Danke!

Len said:
You cannot put a 30amp cb on #14 wire. You really should get a licensed electrician to properly do work.
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If the label says MCA 15a and MOC 30a, you sure can. Note the note at the bottom of Table 310.16.
 
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Len said:
You cannot put a 30amp cb on #14 wire. You really should get a licensed electrician to properly do work.
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Len you can put a 30 amp breaker with a #14 branch circuit in certain situations. The a/c is one of them. The unit is protected with an internal overload protection. The 30 amp is only for ground fault or short circuit protection.
 
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