Feed Subpanel from existing outlet?

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Old 06-20-18, 12:39 PM
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Feed Subpanel from existing outlet?

I am installing a split ac system in my garage which uses 110v. I got a quote for a subpanel from my main breaker and because the wiring would have to go under my driveway or have all kinds of conduit in weird places, the cost was outrageous. I have an existing normal outlet inside the wall where I want to install the subpanel. Can I reroute the cable from the existing outlet to the subpanel as the feed if I use conduit through the wall to the outside?

Hopefully this is enough information. I can provide more if needed. Iím a little worried that may not meet code which would cause me problems if I ever try to sell the house.
 
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Old 06-20-18, 01:18 PM
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The mini split needs a dedicated circuit. It would be rare to have a dedicated circuit for one outside receptacle . Why did someone suggest a subpanel for one circuit ?
 
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Old 06-21-18, 09:30 AM
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The instructions say I need a subpanel since the electricity is provided from outside to the outside unit. Iím assuming taking off the outlet and running conduit from inside from the garage straight to the outside ac unit is even more rare than at least going through a subpanel box.
 
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Old 06-21-18, 09:50 AM
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Sounds like a bonehead translated the instructions. You might need a fused disconnect. Call the manufacturer. The unit is 120v only isn't it?
 
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Old 06-21-18, 11:13 AM
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Yes 120V. I know what Iím trying to do is not normal and trying to do it myself. I just donít want to pay thousands for 1 120v line to be run to a subpanel when I have an indoor outlet right behind the wall. I read the mini split should be the only thing on the circuit but since I want to pull from an existing outlet, I know itís not (plus I see the other outlets on that circuit). Iíve read some people add a simple plug to the wire outside the outside unit but online the manufacturer says not to do that. So basically Iím thinking if I disconnect the outlet, put in a small subpanel outside and feed the line to that, then feed the ac from that subpanel then either 1) itís ok to do that per code or 2) it wil look so legitimate that an inspector may not catch it if I ever sell the home. Of course if someone tells me this is not safe to do then Iíd never put a new homeowner at risk and Iíll just not install the unit at all. I canít see paying $2000 for the correct electrical to install a $800 ac. Iíd just buy a window unit I can plug straight in and hope it keeps the room a little cooler.
 
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Old 06-21-18, 11:16 AM
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Using a subpanel makes no sense. Even using a fused disconnect make no sense.
 
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Old 06-21-18, 11:37 AM
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Thanks but what does make sense other than a complete run to the main panel? Should just run the wire though the wall and cover it with conduit while outside?
 
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Old 06-21-18, 11:49 AM
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just run the wire though the wall and cover it with conduit while outside?
Yes. Note NM-b can not be run outside even in conduit. You would need THWN wires or UF-b cable to a Jbox and from the jbox to the unit a Seal-tite whip.
 
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Old 06-21-18, 11:53 AM
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A similar if not exact scenario to yours that might use a subpanel is when the total amount of power needed is more than 20 amps and individual pieces of equipment are intended for 15 and 20 amp circuits. An alternative to a subpanel is individual branch circuits from the supra panel with amperes ratings to suit individual devices or groups of small amperage devices. Good practice although not always a requirement is a separate branch circuit for any hard wired (no plug and receptacle) device that could draw more than half the amperes rating of the circuit.

For a detached garage only one circuit is permitted to run to the garage to feed everything there. With a significant amount of power needed, it is common to put a subpanel in the garage since the feeding circuit would need to be for more than 20 amps (maybe more than 30 amps) while branch circuits of no more than 20 amps each are needed for the lights and receptacles..

I should question your use of tapping into the wiring behind an ordinary receptacle to run your air conditioner. There is the question of whether that circuit (at most 20 amps) will run both halves of the AC unit and leave enough circuit capacity for other things in the garage.
 
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Old 06-21-18, 12:02 PM
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Thanks to all for you input.
 
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Old 06-21-18, 12:25 PM
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In some cities a disconnect switch needs to be on the wall outside near where the outside half of the A/C unit sits.
 
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