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Old 06-17-2013, 12:02 PM   #1
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Disconnect for Mini split


I need to install a disconnect for a mini split heat pump. these are the power specs.

Outdoor Unit Power 208-230/VAC-1Ph-60Hz

Available voltage range 187-253VAC

Fuse Size, Max 30A

MCA 15.5A

what size wire would I use and is there a special way to hook it up. would the inside breaker be 15A and fuses no bigger than 30A. Any info would appreciated.

Anthony M

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Old 06-17-2013, 12:19 PM   #2
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Disconnect for Mini split


Inside breaker would be 30a. I would use #12 wire

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Old 06-17-2013, 12:21 PM   #3
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Disconnect for Mini split


You need to wire it with #12 and your breaker can be up to 30 amps. I wouldn't go less than 25. You'll feed the condenser and the AHU is wired off of that.

On a mini-split, the disconnect would just go outside with the condenser.
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Old 06-17-2013, 12:27 PM   #4
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Disconnect for Mini split


Thanks for the quick reply guys.....what size fuses for disconnect and should I use 12/2 or 12/3.

Thanks

Anthony M
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Old 06-17-2013, 12:35 PM   #5
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Disconnect for Mini split


12/2 to the disconnect, provided the wiring isn't outside. Then from the disconnect to the condenser with some liquid tight conduit and THHN wire.

The disconnect outside should just be a non-fusible pull out. The breaker is the "fuse".
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Old 06-17-2013, 12:56 PM   #6
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Disconnect for Mini split


The disconnect will be mounted on the house and the wire will enter through the rear of the box.
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Old 06-17-2013, 01:05 PM   #7
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Disconnect for Mini split


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Originally Posted by amoscara View Post
The disconnect will be mounted on the house and the wire will enter through the rear of the box.
That's cool.

There needs to be a receptacle within 25 feet and on the same level for servicing.
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Old 06-17-2013, 02:20 PM   #8
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Disconnect for Mini split


I do have a 15A outdoor receptacle which will be about 4' away from the disconnect, would that good. Also what does MCA 15.5A mean
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Old 06-17-2013, 02:44 PM   #9
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Disconnect for Mini split


Yes, the receptacle is fine. MCA= minimum circuit ampacity. So, you have to have a circuit that can handle a minimum of 15.5 amps and the maximum breaker size is a 30. Different rules apply to motors and HVAC equipment.

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Old 06-17-2013, 04:50 PM   #10
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Disconnect for Mini split


One more question...should the 30A breaker be a single or double pole...Im thinking double if I need 230......
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Old 06-17-2013, 04:51 PM   #11
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Disconnect for Mini split


Double pole
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Old 06-17-2013, 06:11 PM   #12
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Disconnect for Mini split


You could run #14 AWG if you wanted.

Also, nobody ever does this, but a disconnect is required on the inside as well... just saying.
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Old 06-17-2013, 09:22 PM   #13
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Disconnect for Mini split


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Originally Posted by stickboy1375 View Post
You could run #14 AWG if you wanted.

Also, nobody ever does this, but a disconnect is required on the inside as well... just saying.
I was wondering about that 'cause I had heard some talk about it and never researched it. Is that an '08 or '11 thing?
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Old 06-18-2013, 12:02 AM   #14
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Disconnect for Mini split


Quote:
Originally Posted by amoscara View Post
I need to install a disconnect for a mini split heat pump. these are the power specs.

Outdoor Unit Power 208-230/VAC-1Ph-60Hz

Available voltage range 187-253VAC

Fuse Size, Max 30A

MCA 15.5A

what size wire would I use and is there a special way to hook it up. would the inside breaker be 15A and fuses no bigger than 30A. Any info would appreciated.

Anthony M
Just becarefull with this part some inspectors will nail ya on this part.

Did the nameplate mention breaker as well ? if so you are good to go.

Normally for moi .,

Using the NEC art 430 et 440's

The conductor size is 14 awg size but normaly 12 awg will work just fine for this purpose

Max OCPD ( it can be breaker or fuse if the nameplate say either one or both ) will be 30 amp.

But a gotcha is if your unit say fuse only then install the outdoor fuseable A/C disconnect switch and install 30 amp time delay fuse that will take care of that ( the breaker can be still at 30 amp in the breaker panel )

I belive that was changed not too long ago but not sure which cycle they did enforce this part.

Merci,
Marc
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Old 06-18-2013, 03:48 AM   #15
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Disconnect for Mini split


Coming up through the ranks,I was always taught if you are feeding a fusible disconnect,you used wire size to compliment size of disconnect and fuse down at that point.

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