Air Conditioner hookup

Old 06-15-15, 12:10 PM
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Air Conditioner hookup

Hi All...

I'm installing a Mitsubishi split system ductless 12K BTU AC unit. I think I have the process laid out, just want to confirm a few things. First, the specifics of the install: 240V, 15A feed (using 14-2) from panel to a disconnect box on the outside wall. From there a liquid tight flexible conduit carrying more 14-2 runs to the power input panel of the external unit. Lastly, a 14-3 connection runs along with refrigerant pipes from the external unit up the outside wall and then thru into the living space and connects to the wall mounted internal unit. These are the specs from the install guide..mine is the 2nd column.

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Now, a couple questions:

- For the 240 volt feed I use the same standard 14 gauge wire that I would use for your basic lighting circuit...right? I've not done that before so it seems a little strange to run 240 though that small of a wire...but there are plenty of 2-pole 15A breakers out there, so I guess it's "normal".

- the disconnect box is/will be non-fused. I can only find 60 amp models at Lowes/HD...will that be ok to use?

- for the 14-2 run that goes thru the liquid tight conduit I was going to use individual THHN conductors...ok? Should I use 2 blacks since they're both hot? black & red? black & white?

I will also be running grounds for all connections as well.

Thanks in advance...
Old 06-15-15, 12:19 PM
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The ampacity determines the wire size, not voltage.

The disconnect can be rated for 30 or 60 amps. That is the maximum circuit size so you have no issues with either.

The white in a cable will need to be marked as a hot. Use individual conductors in the conduit. Two blacks and a green are fine. You could also use black and red if you like.
Old 06-16-15, 03:37 AM
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The 3 wires up to the inside unit could be run up along side of the ref. piping in PVC pipe and changed over to LT flex on both ends.
Just Saying!

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