Wiring 220 Compressor - Hook Up to Dryer Outlet?

[bulletpruf]

Fellas -

I'm in a rental house, but only for about 6 more months. I need to get my Quincy compressor going -- it's an 80 gallon unit, has a 23 amp Baldor motor, and it's only about 8' from the dryer outlet. The circuit breaker for the dryer is 30 amp, which should work mighty fine.

Isn't this as easy as buying the correct cord from Lowe's, along with a dryer plug, and then wiring the cord to the compressor and plugging it into the wall?

Thanks,

Scott

 

[Aceman]

Can you do it? Yes.

Is it code legal? Absolutely not.

The dryer wiring, breaker, and receptacle are all not rated for a 23 amp 5HP rated motor.

 

[bulletpruf]

Can you do it? Yes.

Is it code legal? Absolutely not.

The dryer wiring, breaker, and receptacle are all not rated for a 23 amp 5HP rated motor.

Ok, can you help me understand what the issue is? Is it just not code legal or is it potentially unsafe?

What I'm seeing - the dryer is either 23 or 25 amps (similar models have slightly different motors). If the breaker, wiring, and receptacle are good for a 23 amp dryer, why wouldn't this all work for a compressor that needs 23 amps?

I have limited experience with this type of stuff, so it's entirely possible I'm missing something here.

 

[Norcal]

Ok, can you help me understand what the issue is? Is it just not code legal or is it potentially unsafe?

What I'm seeing - the dryer is either 23 or 25 amps (similar models have slightly different motors). If the breaker, wiring, and receptacle are good for a 23 amp dryer, why wouldn't this all work for a compressor that needs 23 amps?

I have limited experience with this type of stuff, so it's entirely possible I'm missing something here.

One reason is that the receptacle is not rated for 5 HP, as Aceman correctly pointed out, the circuit has to be sized from NEC Table 430.248 which means that the minimum circuit is 35A, for a 5 HP single phase motor, which means if NM cable is used 8AWG is the minimum size wire, and if the receptacle is a 3-wire device, it is a non grounding, dual voltage 125/250V rated, the "L" shaped prong on those devices is a neutral, not a grounding conductor, because of 120 volt controls & drive motor on clothes dryers, even if a 4-wire receptacle exists it's still not code compliant to run a 5 HP 1Ø motor from it.

 

[shaggyant]

Ok, can you help me understand what the issue is? Is it just not code legal or is it potentially unsafe?

What I'm seeing - the dryer is either 23 or 25 amps (similar models have slightly different motors). If the breaker, wiring, and receptacle are good for a 23 amp dryer, why wouldn't this all work for a compressor that needs 23 amps?

I have limited experience with this type of stuff, so it's entirely possible I'm missing something here.

Read this for an explanation of why it is not code legal

https://www.ecmweb.com/motors/motor-nameplate-current-vs-nec-full-load-current-values

As far as safe goes. The circuit breaker is there to protect the wire and receptacle not your compressor. Keep that in mind if you do decide to try it.

 

[bulletpruf]

One reason is that the receptacle is not rated for 5 HP, as Aceman correctly pointed out, the circuit has to be sized from NEC Table 430.248 which means that the minimum circuit is 35A, for a 5 HP single phase motor, which means if NM cable is used 8AWG is the minimum size wire, and if the receptacle is a 3-wire device, it is a non grounding, dual voltage 125/250V rated, the "L" shaped prong on those devices is a neutral, not a grounding conductor, because of 120 volt controls & drive motor on clothes dryers, even if a 4-wire receptacle exists it's still not code compliant to run a 5 HP 1Ø motor from it.

Ok, that makes sense. It's a 3 prong plug on the dryer.

Thanks

 

[bulletpruf]

Read this for an explanation of why it is not code legal

https://www.ecmweb.com/motors/motor-nameplate-current-vs-nec-full-load-current-values

As far as safe goes. The circuit breaker is there to protect the wire and receptacle not your compressor. Keep that in mind if you do decide to try it.

Ok, that makes sense. If it matters, I would only be plugging it in for a few hours at most on a weekend.

If I did end up wiring up my compressor, what wire should I use? Would it make sense to check to see what size and type wire is running from the dryer to the breaker box?

I think it would be fairly expensive to hardwire my compressor. The breaker box that the dryer and kitchen stuff are hooked to is a 60 amp sub panel and it's full. It's also on the other side of the house (about 30' from the compressor). There's a box that's a lot closer (5' away), but it's already full of 20 amp breakers.

So, if it would cost me $300 to have my 80 gallon compressor hard wired, and we're only going to be here for 6 more months, I'd just buy a cheap/loud compressor that runs on 110 and get rid of it when we move.

EDIT - I could also just get a generator to hook it up to. Figure 5000W is about right?

Thanks

Scott

 

[Lassen Forge]

My dad did it, and about every 3rd time it would pop a breaker, as the breaker and wiring and receptacle are rated for constant, not surge. You're drawing way more than that 23 amps when that motor starts up, then levels off.

Can it be done? Sure. But you're gambling the wiring, etc., are built to handle that oversurge on start up. If it's sufficiently overbuilt and over-engineered, then you're golden; if not, then the flames at the breaker box or inside the walls will be...

 

[Sureshot]

My dad did it, and about every 3rd time it would pop a breaker, as the breaker and wiring and receptacle are rated for constant, not surge. You're drawing way more than that 23 amps when that motor starts up, then levels off.

Can it be done? Sure. But you're gambling the wiring, etc., are built to handle that oversurge on start up. If it's sufficiently overbuilt and over-engineered, then you're golden; if not, then the flames at the breaker box or inside the walls will be...

The breaker is there to protect the wiring.

I would do it in a heartbeat. I pounded steel posts in my yard years ago and wanted to weld tabs onto them to bolt my 2x4 rails so I called a sparky friend to borrow a chunk of heavy cable to run my buzzbox. He had me use the 14/2 wire I had on hand for the basement remodel as the duty cycle would be so low it would never heat the wire. It worked perfect. Be smart about it and don't run the compressor non-stop and be sure to unplug it when you are done.

 

[Bert_]

The plug isn't HP rated and the wire is marginal.

The plug is really only an issue if you try unplugging it when running. I wired lots of 5hp motors with #10 NM for years before I knew better. It doesn't make it right but it's never been an issue either.

The breaker will probably trip sometimes on start up. 5hp motor should have 40A breaker minimum 50A is better to keep from tripping on startup.

Code allows up to a 70A breaker with #8NM or #10THHN for a dedicated motor circuit. What your proposing is not a dedicated motor circuit so I'd keep the 30A and deal with the occasional trip.

I don't blame you for not wanting to spend money on someone else's property. I'd run it on the dryer plug for now and wire it properly when you get your own place.

 

[Bretny]

If a 120v job will do the trick i would be looking on Clist right now.

 

[pattenp]

Ok, can you help me understand what the issue is? Is it just not code legal or is it potentially unsafe?

Since electrical code is to provide safety; if it's not code compliant then it's potentially not safe. If it's potentially not safe then it's most likely not to code.

 

[wyliesdiesels]

What brand model breaker panel do you have? If its a zinsco or FPE, i would not be doing this seeing as how those breakers dont always trip when they should.

Also, since this is a rental you should not be modifying anything.

Is the dryer outlet wired to a subpanel?

 

[JRC3]

If a 120v job will do the trick i would be looking on Clist right now.

And then turn around and resell it for what you paid for it. Free rental.

 

[bulletpruf]

What brand model breaker panel do you have? If its a zinsco or FPE, i would not be doing this seeing as how those breakers dont always trip when they should.

Also, since this is a rental you should not be modifying anything.

Is the dryer outlet wired to a subpanel?

Yes, the dryer outlet is wired to a subpanel. At least that's what I think it is. The main breaker box is about 5 feet from the compressor, but it's already full, and all 20 amp breakers. The subpanel is outside, about 35' from the compressor, and has all the heavy duty stuff - kitchen, dryer, etc. I think it's called a 60 amp subpanel. And it's full, too; no room for more breakers. But I can only imagine how difficult it would be to hardwire something to it, since I would need to run the wire to it.

Thanks

 

[bulletpruf]

If a 120v job will do the trick i would be looking on Clist right now.

Yeah, it would do the trick for now, but space is a premium in the garage, so I'm not sure this is a good idea.

 

[bulletpruf]

The plug isn't HP rated and the wire is marginal.

The plug is really only an issue if you try unplugging it when running. I wired lots of 5hp motors with #10 NM for years before I knew better. It doesn't make it right but it's never been an issue either.

The breaker will probably trip sometimes on start up. 5hp motor should have 40A breaker minimum 50A is better to keep from tripping on startup.

Code allows up to a 70A breaker with #8NM or #10THHN for a dedicated motor circuit. What your proposing is not a dedicated motor circuit so I'd keep the 30A and deal with the occasional trip.

I don't blame you for not wanting to spend money on someone else's property. I'd run it on the dryer plug for now and wire it properly when you get your own place.

Appreciate the input.

If I end up doing this, what wire should I buy? This is something I can get at Lowe's or Home Depot, right?

Thanks

Scott

 

[wyliesdiesels]

For 5HP You will need #8/2 nm-b or #10 THWN in conduit.

Since the breaker box is not within sight of the comp you will need a disconnect as well. You would hardwire the compressor to the disconnect.

An A/c pullout disconnect would work

 

[bulletpruf]

For 5HP You will need #8/2 nm-b or #10 THWN in conduit.

Since the breaker box is not within sight of the comp you will need a disconnect as well. You would hardwire the compressor to the disconnect.

An A/c pullout disconnect would work

Thanks, I appreciate it.

 

[brewchief]

Can you post up some pics of the panels? Try to get a pic of the labels on them if you can as well, it may be possible to use a couple of tandem breakers to make room for a two pole for a compressor.

Sent from my XT1254 using Tapatalk

 

[bulletpruf]

Here's the box that the dryer is wired to.





Here are the breakers. That's a 30 amp 2 pole for the dryer circuit, right?



Dryer plug



Here's the compressor



And here's the other panel. This is the one that's about 6' from the compressor.

 

[nadogail]

In a rental, I would do this in a heart beat. I would "time share" the circuit between the compressor and the dryer.
In a previous house, I "time shared" the dryer and my table saw.
My welder, a Hobart Stickmate, was shipped from the factory with a 12 AWG power cable.

 

[wyliesdiesels]

Yes, the dryer outlet is wired to a subpanel. At least that's what I think it is. The main breaker box is about 5 feet from the compressor, but it's already full, and all 20 amp breakers. The subpanel is outside, about 35' from the compressor, and has all the heavy duty stuff - kitchen, dryer, etc. I think it's called a 60 amp subpanel. And it's full, too; no room for more breakers. But I can only imagine how difficult it would be to hardwire something to it, since I would need to run the wire to it.

Thanks

that panel you pictured next to the meter, which the dryer is connected to, is NOT a subpanel. It is the main service panel.

 

[marinusdees]

In a rental, I would do this in a heart beat. I would "time share" the circuit between the compressor and the dryer.
In a previous house, I "time shared" the dryer and my table saw.
My welder, a Hobart Stickmate, was shipped from the factory with a 12 AWG power cable.

Amen. Long ago, I did something similar while living in married student's housing at the University of Washington. Bungalow had a plug for electric range, and I added an outlet for a dryer. Same breaker, only dried clothes when not using range. Worked. Didn't burn the house down. Would never have passed inspection. Did I worry about a fire. Not even.

 

[yhprum]

I may or may not have done this same thing when I lived in the US .
I bought the plugs and heavy cable at the big box store and made about a twenty foot extension cord. The Husky branded 60 gallon compressor, and mig welder never tripped a breaker. The 3 prong plug never looked like it got hot. I always unplugged it when I was done with it.

 

[alfredeneuman]

Here's the compressor

Did that cable come with the compressor?
It doesn't look like it's cord; more like tray cable or NM.

 

[bulletpruf]

Did that cable come with the compressor?
It doesn't look like it's cord; more like tray cable or NM.

No, that's what the electrician used to wire it up with in Italy. It was plugged into an outlet on the wall on the garage.

 

[Norcal]

That explains the pin and sleeve plug.