AC Disconnect advice

[battmain]

I've decided to go with a mini split for my room. I am in the planning stages right now. The new condenser unit I plan to get requires 208-230v, 15amps. Where I plan to mount the unit on the wall, within 5FT, there is a disconnect switch for the sprinkler pump. Inside the existing disconnect, there are two 10 gauge black wires, two 30amp time delay fuses. One side of that disconnect box then goes to the main service disconnect.(1FT distance) Currently the sprinkler pump is disconnected. The other side of the disconnect has three wires. Two black and one green. The easy way out would be to use those same wires to the new condenser, but eventually the sprinkler will be fixed. Once the ac on this side is done, I'll have more questions for the other split unit on the other side of the house.

I can run wires without getting electrocuted and I can follow instructions. I will also pull permits for the AC install.

What's the best way to go?

 

[Aceman]

I've decided to go with a mini split for my room. I am in the planning stages right now. The new condenser unit I plan to get requires 208-230v, 15amps. Where I plan to mount the unit on the wall, within 5FT, there is a disconnect switch for the sprinkler pump. Inside the existing disconnect, there are two 10 gauge black wires, two 30amp time delay fuses. One side of that disconnect box then goes to the main service disconnect.(1FT distance) Currently the sprinkler pump is disconnected. The other side of the disconnect has three wires. Two black and one green. The easy way out would be to use those same wires to the new condenser, but eventually the sprinkler will be fixed. Once the ac on this side is done, I'll have more questions for the other split unit on the other side of the house.

I can run wires without getting electrocuted and I can follow instructions. I will also pull permits for the AC install.

What's the best way to go?

Get a permit. Run a new 12-2 dedicated to your new condenser unit.

Is your panel within sight of your condenser unit? If it is, you don't need a disconnect. You also need a 120v service receptacle within 25' of your condenser.

I usually buy the ac disconnects with the gfci receptacle inside it. Looks a lot cleaner than two seperate boxes, they're easy to wire, you just run two seperate circuits to it.

 

[battmain]

Get a permit. Run a new 12-2 dedicated to your new condenser unit.

Is your panel within sight of your condenser unit? If it is, you don't need a disconnect. You also need a 120v service receptacle within 25' of your condenser.

I usually buy the ac disconnects with the gfci receptacle inside it. Looks a lot cleaner than two seperate boxes, they're easy to wire, you just run two seperate circuits to it.

The service entrance is 15 ft from the panel, but I'd have to go through the main conduit into the house. I think it might be easier to just run the new wires from the main service disconnect to a new disconnect with it's own fuses.

I'm assuming the 120 leg would be used if the other parts of the unit needed it. Attached is a partial screen capture from the installation manual of the unit I'm looking at. It 'appears' that the 120 leg is provided via the condenser. Please feel free to set me straight.

Another idea I was thinking of, is to replace the existing 30 amp disconnect with a 60 amp disconnect (and new wiring), then run two separate 30amp circuits off that.

 

[Aceman]

Run a dedicated circuit from your main panel to the outside condenser. Tapping off a 60 amp disconnect for two 30 amp circuits isn't the way to do it. It looks like you need to run a 3 wire?? cable + ground from the outside unit to the indoor unit with a 3 pole disconnect, I don't know why 3 pole though, this is all single phase.

I personally haven't wired a mini split before, I'd want to look at it first if at all possible before running the wire. I don't like the 3 pole disconnect as well as the 3 wire cable or the fact you're feeding one unit from another. Seems hokey...

 

[VHF]

One unit feeding the other is the norm for mini-splits. I think it is typical to run a UF cable along with the linesets. Certainly different from central A/C!

But that disconnect between the indoor and outdoor unit seems a little odd... I would think a lockable disconnect feeding power to the outside unit would meet code requirements.

They don't really say what the 3rd wire 'S3' is being used for... is there also a low-voltage cable between the units, or are they using S3 to swtich the compressor? Presumably they expect you to run 12/3 or 14/3 UF between the outdoor and indoor units.

(BTW, I don't think the mini-split uses 120V internally... I think the whole thing--compressor, fans, control board--is powered by 240V so you only need two hots and a ground.)

 

[phbsales]

With a 230 volt mini-split, the indoor unit is powered off of the condenser. A disconnect is necessary at the condensing unit.

120 volt mini-split systems are powered independently from indoor to outdoor unit. The only things connecting the two are the communication wires and the refrigerant lines.

 

[battmain]

One unit feeding the other is the norm for mini-splits. I think it is typical to run a UF cable along with the linesets. Certainly different from central A/C!

But that disconnect between the indoor and outdoor unit seems a little odd... I would think a lockable disconnect feeding power to the outside unit would meet code requirements.

They don't really say what the 3rd wire 'S3' is being used for... is there also a low-voltage cable between the units, or are they using S3 to swtich the compressor? Presumably they expect you to run 12/3 or 14/3 UF between the outdoor and indoor units.

(BTW, I don't think the mini-split uses 120V internally... I think the whole thing--compressor, fans, control board--is powered by 240V so you only need two hots and a ground.)

It seems that the indoor unit is powered by a DC inverter. There is no low-voltage cable that I can see. The diagram shows the only electrical connection, other than the refrigerant lines. The install manual specs 14 gauge wire.