Combo A/C disconnect and GFI

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Derating never crossed my mind. Yeah, someone might plug their Christmas display into it, but do you usually run the a/c in December? (OK, you do in Florida. :p )
 
You still are over 3 current carrying conductors so ampacity adjustments are necessary, however if you can start adjustments at 90C values your end result comes out being same conductor size needed, as long as any possible ambient temp adjustments don't get you into needing a different size conductor.:angel:
 
electrofelon said:
Uh, it's an AC unit, we are not restricted to the small conductors ampacify ;)
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But a circuit with 15/20 amp general purpose 120 volt receptacle outlet(s) is limited to the small conductors ampacity rules. (at least I am pretty certain it is - I did not look to verify)

electrofelon said:
But are you over the MCA of the unit?
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I guess I haven't been around enough mini-splits to know for certain, but your typical unit with an AC compressor that has MOCP of 20 amps usually will not have an MCA much higher then maybe 12 amps - but this would be for typical across the line starting for typical induction type motors, if there is a motor design involved with reduced starting current then you could get the MCA closer to the MOCP
 
kwired said:
I guess I haven't been around enough mini-splits to know for certain, but your typical unit with an AC compressor that has MOCP of 20 amps usually will not have an MCA much higher then maybe 12 amps - but this would be for typical across the line starting for typical induction type motors, if there is a motor design involved with reduced starting current then you could get the MCA closer to the MOCP
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I have seen them with MCA and MOCP pretty close to each other. Something like 18.2 and 20.
 
ActionDave said:
I have seen them with MCA and MOCP pretty close to each other. Something like 18.2 and 20.
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Those probably have reduced current starting methods or motor types that don't have that high of a starting current to begin with - like I said I haven't been around all that many of these to know them that well.
 
Using one leg of the disconnect doesnt always work out.
The GFI receptacle is not a motor load and the same rules dont apply to it as does the AC Unit.

Although you can upsize the breaker for the feed to AC Unit, if you do, and the overcurrent/short circuit protection is above 20 amps, I dont feel you could tap one leg to feed the receptacle above its rating , unless I'm reading it all wrong.


JAP>
 
jap said:
Using one leg of the disconnect doesnt always work out.
The GFI receptacle is not a motor load and the same rules dont apply to it as does the AC Unit.

Although you can upsize the breaker for the feed to AC Unit, if you do, and the overcurrent/short circuit protection is above 20 amps, I dont feel you could tap one leg to feed the receptacle above its rating , unless I'm reading it all wrong.


JAP>
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Pretty much but you could tap the line side and add a inline 20 amp fuse for the receptacle.
 
iwire said:
Pretty much but you could tap the line side and add a inline 20 amp fuse for the receptacle.
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Which opens another can of worms that has been debated here before regarding definitions of feeders and branch circuits - and whether that inline fuse is a branch circuit OCPD or a supplemental device.
 
kwired said:
Which opens another can of worms that has been debated here before regarding definitions of feeders and branch circuits - and whether that inline fuse is a branch circuit OCPD or a supplemental device.
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No need to over complicate it.
Just call it something that makes the receptacle work. :p

JAP>
 
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