Compressor Wiring Help (pics attached)

[Boyd]

When our house was being built, I asked the electrician to include a 230v circuit. I only need 30amps for my compressor, but asked for a 50a circuit because I plan to add a welder or possibly a powder coat oven to my arsenal in the future. Since the builder wasn't sure what type of outlet to install he just ran the circuit (looks like 8/3) and covered it with a blank plate.

Well, I'm no electrician and haven't slept at a Holiday Inn recently, so here's where I need help.

How do I get this:

to plug into this?

with the ability to add a welder later on and not have any issues with the compressor motor in the mean time?

For reference, the motor on the compressor is rated 230v/15a (the plug in the pic is something I added for my previous garage)

Will I need to replace the 50a breaker for ,say, a 30a? Which outlet/plug do I use?

 

[Dan0myte]

You have to go buy one of these:

Install it in your box. Go to your circuit breaker panel and install a 30A circuit breaker on that line. That's it, done. Plug your Air Compressor in and start compressing air!

If down the road you do eventually buy a welder or device that draws more than 30 amps, then you can revisit the issue and look into getting the proper 50A circuit breaker, 50A outlet and 50A plugs for the devices. But since you don't have the high draw devices yet, I would say wait to buy the 50A hardware until you know exactly what kind of plug your devices will use.

 

[KCarGuy]

Most 220V welders will come with a "Range Plug", a straight blade plug same as most electric driers.
What you have there, is a "Twist lock" plug...a L6-30.
you could install a L6-30R "Twist Lock" Outlet and simply plug your compressor in...Or install a 30 Amp 220V "Range Plug" Outlet and make a "Cheater Cord" about 3 feet long with a "Range Plug" recepticle on on side and a "Twist Lock" Outlet on the other so you can plug in the compressor, or remove the "Cheater" and plug a welder straight into the outlet. (Or the other way around).

I have a "Range Plug" on my wall that My Welder plugs right into. and a "Cheater Cord" for a Second 220V Compressor if I need to.

 

[Boyd]

Thanks. Will that outlet allow for 3 conductors?

 

[Dan0myte]

Thanks. Will that outlet allow for 3 conductors?

No, two hots and a ground. The red wire will not be used in your case. I'm not quite sure why your electrician ran 8/3 in the first place unless he thought you might install a stove in your garage...

 

[KCarGuy]

Yes, Both Outlets are set up for a 3 wire 220V single phase wiring.

Twist Locks are Nice because they are inserted and removed easily, but dont fall out due to the twist design.

110V to Ground on X
110V to Ground on Y
220V from X to Y

Good Luck.

 

[KCarGuy]

Changes are, that your RED is a hot lead, Your BLACK is a hot lead and your WHITE is a Nuetral.
The Bare Copper wire should be Grounded to your Metal Box.
BUT...Check with a Meter first before wiring or plugging anything in.

Good Luck

 

[Dan0myte]

Yes, Both Outlets are set up for a 3 wire 220V single phase wiring.

3 wires, yes, but 2 conductors.

110V to Ground on X
110V to Ground on Y
220V from X to Y

You wouldn't want to run a device from X/Y to ground though... That's just for if you plug a meter into X/Y to ground you will see 110V, yes, which is correct.

 

[Charles (in GA)]

No, two hots and a ground. The red wire will not be used in your case. I'm not quite sure why your electrician ran 8/3 in the first place unless he thought you might install a stove in your garage...

The elec ran 8/3 because he asked for a 50 amp circuit and had no idea if he needed a neutral or not.

The above statement is incorrect, the WHITE wire (neutral) is the one that will not be used. Put a wing nut cap on it and fold it back in the box, hook up the red and black and the bare ground.

If you are using a 30 amp receptacle to match that twist lock, you will need a 30 amp circuit breaker on the circuit, despite the fact you have the heavier wire. If and when you need to upgrade to the full 50 amp capability, you can change out the breaker.

Charles

 

[JBurgess]

The elec ran 8/3 because he asked for a 50 amp circuit and had no idea if he needed a neutral or not.

Isn't 8/3 romex only good for 40 amps?

 

[Boyd]

Thanks to all for the advice. I'm waiting on some repair parts to come in for my compressor and wanted to get it wired before they arrive. This helps a bunch.

 

[Boyd]

Isn't 8/3 romex only good for 40 amps?

It would appear so. When I went to install the new 30a breaker the existing breaker was 40a.

Question: I just finished wiring the outlet, turned the breaker on, and hit the switch on the compressor. I could tell right away something was not right, so immediately turned it off. Is it possible to get the polarity wrong? Would the motor just run in reverse?

How I wired it:

Red - capped, not used.
Black - "X" position on outlet
White - "Y" position on outlet
Ground - Ground position on outlet

 

[Boyd]

The above statement is incorrect, the WHITE wire (neutral) is the one that will not be used. Put a wing nut cap on it and fold it back in the box, hook up the red and black and the bare ground.
Charles

Ok, I see that I should have wired it the above way -as the black/white combo was no bueno! Will report back shortly....

 

[Charles (in GA)]

You said this was 220v/240v. You need to cap the white and hook up the red in place of it. 240v does not use the neutral (white wire) and so you need to cap and stow it. When you turned it on, all it was getting was 120v, which is why it didn't sound right.

Scroll up to my post #9.

Charles

 

[Charles (in GA)]

We were typing at the same time.

Chas

 

[mrb]

you just gave your compressor 120v. This is why I am starting to get sick of the electrical forum here, too many people who have no clue what theyre doing giving improper advice. Its only a matter of time before someone gets hurt or burns their house down.

You are using a L6-30 receptacle. This is a 2P3W 250v receptacle. It gets two hot wires and a ground. You should be connecting Black to X, Red to Y, and Ground to the box and the green screw on the receptacle (or just to the receptacle if its a plastic box). The white wire is not used.

 

[Boyd]

We were typing at the same time.

Chas

It appears we were! Hooked it up the way you suggested and it's humming along just fine. Thank you sir!

...You should be connecting Black to X, Red to Y, and Ground to the box and the green screw on the receptacle (or just to the receptacle if its a plastic box). The white wire is not used.

Thank you for taking the time to post the correct information. Thanks to Charles and yourself, that is how it is now connected. I really appreciate it. Thought I fried a motor there for a second.

 

[mrb]

I forgot to mention, you should replace the breaker with a 30 amp breaker. Cant protect a 30 amp receptacle with a 50 amp breaker.

 

[GeorgiaHybrid]

I forgot to mention, you should replace the breaker with a 30 amp breaker. Cant protect a 30 amp receptacle with a 50 amp breaker.

It would appear so. When I went to install the new 30a breaker the existing breaker was 40a.

I think he did.....

 

[Aceman]

This is why I am starting to get sick of the electrical forum here, too many people who have no clue what theyre doing giving improper advice. Its only a matter of time before someone gets hurt or burns their house down.

I can't believe it took you this long!!!

Lucky me, I get to see a lot of this crappy DIY work doing service calls.

 

[mrb]

I can't believe it took you this long!!!

Lucky me, I get to see a lot of this crappy DIY work doing service calls.

i guess i have alot of patience. I know everyone means well, but there is some pretty bad advice given here from time to time.

 

[babzog]

i guess i have alot of patience. I know everyone means well, but there is some pretty bad advice given here from time to time.

Guys like me appreciate guys like you who do take the time to help those with less knowledge, acquire it to safely complete a job or simply to gain understanding. There are many sites out there where simply howto questions are not tolerated, like the skill must be protected with the determination of stone masons of centuries past. Thank you!

 

[mrb]

Guys like me appreciate guys like you who do take the time to help those with less knowledge, acquire it to safely complete a job or simply to gain understanding. There are many sites out there where simply howto questions are not tolerated, like the skill must be protected with the determination of stone masons of centuries past. Thank you!

and i dont mind helping those who are looking to do something right and are seeking advice. But when 20 other people come along and tell the OP to do this or that and its wrong or dangerous, or say you dont need to do it to code as long as it works, or that permits and inspections arent necessary, its irritating.

 

[Dan0myte]

The above statement is incorrect, the WHITE wire (neutral) is the one that will not be used. Put a wing nut cap on it and fold it back in the box, hook up the red and black and the bare ground.

Not if the white wire is coded hot, which is what I meant in the first place. You would not hook the white wire up to the neutral bar in the subpanel, that would give you 120V and be stupid and not work. I guess I maybe assumed too much in thinking that the OP would know this when I said to only use the two hot conductors...

 

[mrb]

Not if the white wire is coded hot, which is what I meant in the first place. You would not hook the white wire up to the neutral bar in the subpanel, that would give you 120V and be stupid and not work. I guess I maybe assumed too much in thinking that the OP would know this when I said to only use the two hot conductors...

but that cable had a red it in too. why would you even suggest using the white, when the cable has a black and a red?

 

[Dan0myte]

The way I was taught was the black and white were always used in a two conductor situtation no matter what. Whether it be 120v or 240v. In 240v you code the wire end black to signify that it's hot. The only time the red wire ever gets used is in a 3 conductor situtation such as an oven or dryer where the black and red are hot and white is neutral to provide both 240v and 120v. That's the only instance the red wire is used in a non-switching application (3-way, 4-way lights, etc.)

So in this case because the OP's electrician ran 8/3 for him when all he needed was 8/2, I suggested wire capping the red wire and tucking it up and using the black and white to run from a double pole breaker to the plug.

Hah, maybe it's a Canadian thing? We do a few things differently up here?

 

[mrb]

The way I was taught was the black and white were always used in a two conductor situtation no matter what. Whether it be 120v or 240v. In 240v you code the wire end black to signify that it's hot. The only time the red wire ever gets used is in a 3 conductor situtation such as an oven or dryer where the black and red are hot and white is neutral to provide both 240v and 120v. That's the only instance the red wire is used in a non-switching application (3-way, 4-way lights, etc.)

So in this case because the OP's electrician ran 8/3 for him when all he needed was 8/2, I suggested wire capping the red wire and tucking it up and using the black and white to run from a double pole breaker to the plug.

Hah, maybe it's a Canadian thing? We do a few things differently up here?

maybe it is a canadian thing, I am not familiar with the standards and practices there. Typically you would only use the white as a hot when there is no other option. With the 8/3 you have the two hots you need, the neutral is not needed so you leave the white disconnected in the box (it should still be landed on the neutral bar in the panel though)

 

[Dan0myte]

maybe it is a canadian thing, I am not familiar with the standards and practices there. Typically you would only use the white as a hot when there is no other option. With the 8/3 you have the two hots you need, the neutral is not needed so you leave the white disconnected in the box (it should still be landed on the neutral bar in the panel though)

I'm sure either way is acceptable by electrical code.

Recently I took out a permit for rewiring my garage, in which I added a 30A outlet for a Dayton G73 (among other things). The garage had existing 10/3 in the wall so I used that with the new subpanel and did exactly as I mentioned before (black/white hot, red wire capped, ground bonded). The SaskPower inspector passed the work and cleared my permit. So all I can speak from is personal experience. The codes in your State/Province may differ.