AC Disconnect for 120V mini-split

[gamp945]

Hi all,

I am finally adding power to my small outbuilding that I built a while back.

I am going to be using a 120V mini-split.

I have a 240V disconnect box and want to use it on the exterior of the building for the 120V mini split.

Here is what I think I need to do:
-Wire the 120V black/hot from the building's panel and the 120V mini split to each side of the switch
-Connect the white neutrals from the building's panel and the mini split inside the box with a wire nut
-Connect the ground wires from the building's panel and the mini split to the ground bar inside the disconnect box
-Ignore the terminals in the top-left and top-right of the panel that are intended for the second 120V hot wire in a 240V circuit

If I understand correctly, using the 240V disconnect box in this way is not a code violation and the 240V breaker will work normally with the lower voltage. Please correct me if I'm wrong on any of the above!

I've attached a photo for clarity. Thanks for reading

 

[pattenp]

That's just a switch, not a breaker. It gives no overload protection. No problem using just one side of it. You need to use top and bottom of one side. Large lugs at top are line-in, small lugs on bottom of switch are line-out.

 

[Norcal]

That's just a switch, not a breaker. It gives no overload protection. No problem using just one side of it. You need to use top and bottom of one side. Large lugs at top are line-in, small lugs on bottom of switch are line-out.

Read paperwork carefully if my memory serves me correctly that molded case switch is 10 AWG minimum, screwy thing if correct though.

 

[gamp945]

Thanks for the replies.

Norcal: good catch! I looked and the switch is a QO200 which lists a wire size of 8 AWG. I think that means that is the minimum? If so, I obviously can't use this disconnect box. I think it was the smallest one they had at Lowes. Maybe I should just use a 120V toggle switch in a weatherproof box instead.

 

[rlitman]

Thanks for the replies.

Norcal: good catch! I looked and the switch is a QO200 which lists a wire size of 8 AWG. I think that means that is the minimum? If so, I obviously can't use this disconnect box. I think it was the smallest one they had at Lowes. Maybe I should just use a 120V toggle switch in a weatherproof box instead.

The toggle switch will not have the horsepower rating. Use a proper disconnect.
A $10 one with a pull-out is sufficient.

https://www.lowes.com/pd/Eaton-60-A...nclosed-Molded-Case-Switch-Disconnect/1114583

 

[wyliesdiesels]

skip the fancy switches and get a pullout disconnect like posted above. no need to complicate things

also, make sure you have a 120v receptacle within 25' for servicing equipment such as vacuum pump

 

[Norcal]

Non fusible pullout discos are cheap and functional & if a non fusible model is used you can switch both line and neutral and still be code compliant.

 

[gamp945]

Great info guys - I'll get a simple pull-out disconnect.

I do have a 120V receptacle within 25'.

Norcal: can you explain what you mean by your statement regarding switching both line and neutral? I was planning on just wire nutting the neutral lines in the disconnect box.

 

[wyliesdiesels]

Great info guys - I'll get a simple pull-out disconnect.

I do have a 120V receptacle within 25'.

Norcal: can you explain what you mean by your statement regarding switching both line and neutral? I was planning on just wire nutting the neutral lines in the disconnect box.

you cannot switch the neutral/grounded conductor by itself. the grounded conductor can only be switched if the corresponding ungrounded conductor(s) is switched at the same time.

you really dont need to switch the neutral for this but hes just throwing that info out there

 

[rlitman]

...you really dont need to switch the neutral for this but hes just throwing that info out there

You don't NEED to switch the neutral, but if you do, you can skip the wire nut and just use the terminals in the disconnect. It looks cleaner this way.

 

[gamp945]

So using this pullout disconnect as an example (the photos clearly show the line/load terminals):

https://www.amazon.com/gp/product/B000LF42NK/?tag=atomicindus08-20

You are saying that I could wire the hot line/load on one side, then wire the neutral line/load on the other side, and then wire the ground to the ground block?

 

[pattenp]

Read paperwork carefully if my memory serves me correctly that molded case switch is 10 AWG minimum, screwy thing if correct though.

****.. its #8 min. That's the disconnect I tout using for compressors and such. I've got 3 of them in use with #10's hooked up. Oh my..now I won't be able to sleep at nights.

 

[Terry D]

So using this pullout disconnect as an example (the photos clearly show the line/load terminals):

https://www.amazon.com/gp/product/B000LF42NK/?tag=atomicindus08-20

You are saying that I could wire the hot line/load on one side, then wire the neutral line/load on the other side, and then wire the ground to the ground block?

Yes that are what they are saying. It would eliminate a splice and look cleaner. There is nothing wrong with disconnecting the grounded conductor as long as the ungrounded conductor is disconnected simultaneously. You could always put a label on it saying "120 volts"

 

[gamp945]

****.. its #8 min. That's the disconnect I tout using for compressors and such. I've got 3 of them in use with #10's hooked up. Oh my..now I won't be able to sleep at nights.

LOL...glad I was able to help, er, hinder!

Yes that are what they are saying. It would eliminate a splice and look cleaner. There is nothing wrong with disconnecting the grounded conductor as long as the ungrounded conductor is disconnected simultaneously. You could always put a label on it saying "120 volts"

Great - thanks for clarifying