Another electrical question

[Michael Perata]

I want to relocate my air compressor to a location outside my shop and next to my A/C compressor.

I have a 240V 50A disconnect feeding the existing A/C compressor and the tag says the minimum circuit is 31.9 Amps.

The disconnect has a 50 amp breaker and has an unused knockout.

Can I connect my air compressor, 240V 12.9 Amp, to the disconnect box?

I think the math works, I am more concerned about code issues.

Also, I want to put an automatic drain on the air compressor. How can I tap into the 240v circuit to run 110v to the drain?

[David Wilson]

Your math is correct but I would check on the code issue. Any licenced Master electrition in your area can answer that question. As far as the 110v issue, 220v is basicly 2 110v circuits out of fase with each other. You have 2 hot wires and a ground.
Connecting your 110v drain to 1 hot wire and the ground will give you 110v.

[Dennis Peacock]

Yea....you can do what you are asking...

The governing body is....your local electrical codes. Where I live, you can do whatever you like as long as you don't burn your house down or kill someone while you are doing the wiring. :eek: :D

I am an ex-electrician and have wired HUNDREDS of those service disconnects. If your outside breaker says it 50 Amps....you need to check your wire guage coming to the service disconnect. Normally, it's only a #10 guage wire, 2 hots and a ground....which is only really good for 40 Amps tops and 30 amps standard constant load.

50 Amps requires a #6 guage Aluminum wire or a #8 Copper wire.
40 Amps requires a #8 guage Aluminum wire or a #10 Copper wire.

If you see the insulation on the wire coming into the disconnect and it is WHITE or off White or some resemblance of white and plastic...it is Romex wire and is only a MAX of 40 Amps...(In case it's a #10 copper wire).
If you see Gray insulation and plastic on the outside...it can be any size wire between #8 and 1 Aught Service entry cable.

I guess I've said too much here.

<b>Check your local building codes.!!! It's not worth killing yourself or other over, nor is it worth setting fire to your house while you are asleep.!!!!</b>

The usual disclaimers apply here.....I know not what what I'm doing.. ;) :p

[Michael Perata]

David/Dennis

It looks like the service is gray plastic clad aluminum 3+ bare gound with the common not used.

I am thinking with a single breaker and needing two 220v and one 110v circuit I might be better off putting 50 Amp weather proof sub panel in.

Any manufacturers suggestions?

[Dennis Peacock]

David/Dennis

It looks like the service is gray plastic clad aluminum 3+ bare gound with the common not used.

I am thinking with a single breaker and needing two 220v and one 110v circuit I might be better off putting 50 Amp weather proof sub panel in.

Any manufacturers suggestions?

Michael,

I prefer the "non-homeline" Square-D boxes, panels and breakers. The breakers and parts for them are every where and very reasonable in prices.

[Rob Russell]

I want to relocate my air compressor to a location outside my shop and next to my A/C compressor.

I have a 240V 50A disconnect feeding the existing A/C compressor and the tag says the minimum circuit is 31.9 Amps.

The disconnect has a 50 amp breaker and has an unused knockout.

Can I connect my air compressor, 240V 12.9 Amp, to the disconnect box?

I think the math works, I am more concerned about code issues.

Also, I want to put an automatic drain on the air compressor. How can I tap into the 240v circuit to run 110v to the drain?



Yea....you can do what you are asking...

The governing body is....your local electrical codes. Where I live, you can do whatever you like as long as you don't burn your house down or kill someone while you are doing the wiring. :eek: :D

I am an ex-electrician and have wired HUNDREDS of those service disconnects. If your outside breaker says it 50 Amps....you need to check your wire guage coming to the service disconnect. Normally, it's only a #10 guage wire, 2 hots and a ground....which is only really good for 40 Amps tops and 30 amps standard constant load.

50 Amps requires a #6 guage Aluminum wire or a #8 Copper wire.
40 Amps requires a #8 guage Aluminum wire or a #10 Copper wire.

If you see the insulation on the wire coming into the disconnect and it is WHITE or off White or some resemblance of white and plastic...it is Romex wire and is only a MAX of 40 Amps...(In case it's a #10 copper wire).
If you see Gray insulation and plastic on the outside...it can be any size wire between #8 and 1 Aught Service entry cable.

I guess I've said too much here.

<b>Check your local building codes.!!! It's not worth killing yourself or other over, nor is it worth setting fire to your house while you are asleep.!!!!</b>

The usual disclaimers apply here.....I know not what what I'm doing.. ;) :p

Michael/Dennis,

If you're trying to meet the NEC, running 2 motors off of a single circuit/disconnect isn't as simple as adding up the motors' data plate FLA ratings.

You need to size conductors, short circuit protection (breakers) and overloads to the motors and combined loads. The calculations are all from Article 430 in the NEC.

What are the HP ratings for the motors on your AC unit and compressor? You've alreay provided the FLA ratings.

Thx - Rob

[Michael Perata]

Rob

I was trying to save the effort of having to crawl my subfloor to run a 220v circuit off my garage sub-panel.

Then I realized if I move the compressor out side I need to pipe for the air. (DUh)

Guess I'll find a small plumber and pull the wire at the same time.

Thanks all for the help!!

[Rob Russell]

Rob

I was trying to save the effort of having to crawl my subfloor to run a 220v circuit off my garage sub-panel.

Then I realized if I move the compressor out side I need to pipe for the air. (DUh)

Guess I'll find a small plumber and pull the wire at the same time.

Thanks all for the help!!

Michael,

What are the HP ratings of your AC unit and compressor?
Is the crawlspace under your shop/garage dirt floor or concrete?

You could do the piping for the air line yourself. That's pretty easy stuff and a great way to learn how to sweat copper without turning off the water in your house. DAMHIKT :D. If you're running an air line underneath the shop and that's anunheated space, it'll get cooler in the winter and become a condensation trap. I'd find a way to run an angled drain pipe with valve to a convenient place to bleed off water from the pipe.

Rob