240v Receptacles

[mbushnell]

Hi Guys,
I am in the process of finishing off my attached 3 car garage.
When the electrician was here doing the rough-in, I had him run a 240v line for a 240v outlet in the garage (in addition to additional 120v outlets & lighting). He was adding 240v circuits anyways for a Mini-Split HVAC in the garage & for a humidifier for the house HVAC System.
Now that the garage walls are insulated & drywalled, his is asking what type of receptacle I want for the 240v outlet. For the moment, he installed a blanking plate over the 240v outlet box.
What do I tell him?
He said that he installed wiring capable of 40 amps, but installed a 30 amp C/B. All that would be required to go to a 40 amp circuit is to change out the C/B.
I was thinking that I would want it for a possible Air Compressor, yet all of the air compressors that I see in my local big box stores are 120v.
Any thoughts? Is there a "standard" 240v receptacle?
Thanks
Mark

 

[KenC]

https://en.wikipedia.org/wiki/File:NEMA_simplified_pins.svg

Lots of them. All depends on the load.

 

[pattenp]

Outlets are either 20A, 30A or 50A in 240V. Compressors with motors larger than 3hp will usually need to be hardwired.

 

[mike93lx]

Don't install a plug until you know what you want to use.

Compressor, welder, heater, table saw, planer, etc can all have different plugs or connection methods

 

[grerobinson]

I recently built a shop and had seven 220 dedicated circuits installed for future use. I had my electrician cap off the boxes until I decide what equipment to install. I plan to install the required outlets for whatever equipment I end up with. My plan is to set up some wood working tools.
I did install a 220v 1-1/2 ton split system HVAC that is hard wired on a dedicated 15 amp breaker.

 

[Stuart in MN]

Don't install a plug until you know what you want to use.

Compressor, welder, heater, table saw, planer, etc can all have different plugs or connection methods

Yes, there's no point in installing one until you know what you're going to use it for.

 

[dcg9381]

And the breaker needs to match the appliance it's on, typically.
For me, as I own an RV, I use the standard 4-pin (good for 50A) connector. It's NEMA: 14-50P. It's easy to find, a solid plug, and basically everything that I have which runs on 240v is now "wall compatible".

Your electrician used 8 gauge wire. This is the cord plug that I use, universally and it's great on extension cords that are 3-conductor and 10-gauge:

 

[wyliesdiesels]

Thats unfortunate the electrician used #8 NM-b because you would not be able to use that for a 50a circuit.

 

[Bert_]

Thats unfortunate the electrician used #8 NM-b because you would not be able to use that for a 50a circuit.

But you could install a 50a receptacle and breaker for use with most welders.

 

[wyliesdiesels]

But you could install a 50a receptacle and breaker for use with most welders.

Yes that would be the one exception.

 

[alfredeneuman]

If you run empty conduits either in the wall or on the surface, you'd be able to tailor the wire, receptacle, and breaker to the various equipment and change them at will.
Look into the future

 

[sberry]

What else needs an 8? Comp can hard wire to it, electric range is about the other thing most own needs a true 50.

 

[mbushnell]

Thanks guys for all the info.
As was stated in the replies, I guess that I will wait until I decide what compressor I will get in order to determine what what receptacle to use or to hard wire it.
The walls & ceiling are getting painted starting on Monday & the floor coating will probably go down later on in the week.
Mark

 

[kaffine]

What else needs an 8? Comp can hard wire to it, electric range is about the other thing most own needs a true 50.

EV's can frequently use 50amp, mine can use up to a 60amp breaker but requires a hardwired EVSE box at that point.

 

[wpozo]

My experience with charging my small tesla is that any 240 volt plug with 20 amps charges the car really fast. So that plug will be great for an electric car. I now live in a rental house and the 120 volt is enough for the most part. a 240/20 is only used with the dryer plug adapter and when i really pushed the charge to zero on a long road trip. Cheers from Virginia.

 

[dcg9381]

Thats unfortunate the electrician used #8 NM-b because you would not be able to use that for a 50a circuit.

I used 50A outlets on a 30A circuit with 10A wire. Wire has to match the breaker... Most things don't pull a full 50A.

On this 30A circuit, I regularly run a welder (MIG) and will run some RV stuff (not together). It's nice to have one "outlet type" for all your stuff.

 

[dcg9381]

What else needs an 8? Comp can hard wire to it, electric range is about the other thing most own needs a true 50.

50A, I wire 6 Gauge. Things that can use 50A:

EVs, at peak charge.
RVs - the really big ones, 3 AC units or more.
Hot tubs (via a GFCI feed)

 

[mike93lx]

I used 50A outlets on a 30A circuit with 10A wire. Wire has to match the breaker... Most things don't pull a full 50A.

On this 30A circuit, I regularly run a welder (MIG) and will run some RV stuff (not together). It's nice to have one "outlet type" for all your stuff.

Wire does not always have to match the breaker. Welders are the most common example.

50a outlet, 50a breaker, 12 gauge is acceptable. I think 14 may even be in some cases.

I used 10thhn for my welder for a little more headroom

 

[mm08822]

Wire does not always have to match the breaker. Welders are the most common example.

50a outlet, 50a breaker, 12 gauge is acceptable. I think 14 may even be in some cases.

I used 10thhn for my welder for a little more headroom

Not #14 on 50A cb. 200% conductor ampacity is max allowed for welder ckt cb's.

 

[dcg9381]

Not #14 on 50A cb. 200% conductor ampacity is max allowed for welder ckt cb's.

Didn't know that.. Thanks, guys... I just don't wire it that way.

What is it that makes it a "welder circuit"? Slapping a label on it?

 

[mm08822]

Didn't know that.. Thanks, guys... I just don't wire it that way.

What is it that makes it a "welder circuit"? Slapping a label on it?

Yes. Scary ain't it?

 

[alfredeneuman]

I've never agreed with the rule allowing reduced wire size for a welder receptacle.
Someone could see the 50A breaker and receptacle and use it for completely different piece of equipment drawing more current than the wire can handle.

 

[Norcal]

I've never agreed with the rule allowing reduced wire size for a welder receptacle.
Someone could see the 50A breaker and receptacle, and plug in a 50A pottery kiln (just as an example).

Don’t care for it myself, but has it been a problem?

 

[alfredeneuman]

Nobody can be sure

 

[sberry]

Yes, when 14 is used it needs 30.

 

[sberry]

Nobody can be sure

I can't say never but I asked this of a fire inspector and at a convention session. Have you ever seen fire from wire on comp or welder? Said,, no. Seen them used and set fire.I think number 1 was heaters, 2 on a tampered circuit or on lamp cords.
**** tampered with, hot light bulb.

 

[dcg9381]

Don’t care for it myself, but has it been a problem?

I can tell you that it'd be a problem in my shop. I have one 50A plug that's up front on 10GA wire, largely for use with a welder. Friends bring RVs and we use the same plug. Putting it on a 50A breaker is not a good idea. I have it on a 30A breaker.

I guess labeling it "welder only" is one solution... I'd just rather be safe than smoke a wire in a wall filled with foam.

RVs can function just fine on 30A @ 240V, but owners need to be aware that they shouldn't run 2 ACs and the micorwave at the same time...

 

[sberry]

Friends bring RVs and we use the same plug. Putting it on a 50A breaker is not a good idea. I have it on a 30A breaker.

Wrong recept, wrong plug to the wrong wire and the wrong breaker,,, none of it code compliant, not the code written wrong.

 

[sberry]

The code allows this wire to a welder outlet, not rv or range.

 

[dcg9381]

Right, but we're "bitchin'" about code, because the style of that welder outlet can be anything... And the highest capacity most easily found outlets are those NEMA 14-50R - which are dryer, range, and just happen to fit my welder..

 

[mike93lx]

Right, but we're "bitchin'" about code, because the style of that welder outlet can be anything... And the highest capacity most easily found outlets are those NEMA 14-50R - which are dryer, range, and just happen to fit my welder..

Then you installed the wrong plug on your welder.

 

[dcg9381]

Fair enough!

 

[wyliesdiesels]

Right, but we're "bitchin'" about code, because the style of that welder outlet can be anything... And the highest capacity most easily found outlets are those NEMA 14-50R - which are dryer, range, and just happen to fit my welder..

Ive never seen a dryer use a 14-50p.

Dryers use a 14-30p...

Also, welders dont use a 14-50p because they dont need a neutral

They use a 6-50p...

So you used the wrong plug and outlet for your welder and this is why the RV could plug into it.

Switch to a 6-50r and p and then only the welder would work on that outlet.

 

[anythingyoucanimagine]

Does this mean I'm not allowed to plug a 120V 30A device into edit: 18-30r ? (stupid siri mistake sorry)

 

[wyliesdiesels]

What is a 6-18r?

 

[mike93lx]

Does this mean I'm not allowed to plug a 120V 30A device into 6-18r?

What device do you have that is 30a 120v? Only thing i can think of is an RV

 

[dcg9381]

So you used the wrong plug and outlet for your welder and this is why the RV could plug into it.

Switch to a 6-50r and p and then only the welder would work on that outlet.

I get it. And yea, welder only needs 3 wires. More "convenient" for me to have everything to one plug type and protect the circuit appropriately.

Had to look up the slight difference between 14-30p and 14-50p, I had that wrong..

 

[anythingyoucanimagine]

What is a 6-18r?

18-30r, I was trying to get Siri to post here and I failed. Sorry. 30a 208y

 

[wyliesdiesels]

18-30r, I was trying to get Siri to post here and I failed. Sorry. 30a 208y

A 18-30r is non grounding so no you couldnt use it for a 120v device.

 

[eeprete]

Came across this thread in a search.

The welder draws higher amps for shorter spikes in time so it should be safe. While you cannot assume anyone will know not to plug a stove in at the garage, one can never be so sure... I've actually seen some recent ads for garages to be rented as living space! Can't wait to see the town come down on that.

As for the OP, build for your long term goals. Dream big, build for that. As for the big box store compressors, you will find a better and more durable compressor on Craigslist or Facebook marketplace, often paying 50% of what they may have retailed for. Also, not everyone needs an 60 or 80 gallon compressor. Not if all you're doing is filling bike tires and blowing out sprinklers. If restoring cars and doing bodywork and paint, yes a 60 or 80 will be of enormous benefit, but most importantly look at the compressor specifications to judge what is best. My 30 gallon CH compressor is almost as powerful as my older 60 gallon speedaire.