Standard 240v 30amp Receptacle

Augus7us · Oct 25, 2018

Hey Gang,

I thought I saw something on this in the past, but I just spent the last 20 minutes searching GJ on google and couldn't find anything.

So I need some help standardizing a receptacle for my 240v tools. Almost all of them will run on a 20 or 30amp circuit so my plan was to run a couple of 30amp circuits with 3 or 4 outlets on each circuit.

I'll also have a few dedicated runs for certain tools.

To be more specific:

What receptacle should I use to future proof my shop and standardize on one receptacle? Would I be better off with 4 wire receptacles? If so can I plug in tools that only use 3 wires? I read you could on here.

What box should I use? I assumed I could just use a 1 gang box but looking at some old threads I saw guys with one receptacle in a 2 gang box. Thinking about it this would probably be better since I'm was planning on 10/3 wire for these circuits.

Thanks

-Clint

wyliesdiesels · Oct 25, 2018

Augus7us said:
Hey Gang,

I thought I saw something on this in the past, but I just spent the last 20 minutes searching GJ on google and couldn't find anything.

So I need some help standardizing a receptacle for my 240v tools. Almost all of them will run on a 20 or 30amp circuit so my plan was to run a couple of 30amp circuits with 3 or 4 outlets on each circuit.

I'll also have a few dedicated runs for certain tools.

To be more specific:

What receptacle should I use to future proof my shop and standardize on one receptacle? Would I be better off with 4 wire receptacles? If so can I plug in tools that only use 3 wires? I read you could on here.

What box should I use? I assumed I could just use a 1 gang box but looking at some old threads I saw guys with one receptacle in a 2 gang box. Thinking about it this would probably be better since I'm was planning on 10/3 wire for these circuits.

Thanks

-Clint

If ALL the tools are 240v only, then why would you need 4-wire outlets?

4-wire outlets are for equipment that needs 120v AND 240v because the 4th wire is a neutral.

240v equipment does NOT need a neutral.

dogdog · Oct 25, 2018

I install all my 240v Capable outlets with 4 wire L14-30R.... it also happens to be popular with generators that has the 30Amp Receptacles... If all I wanted is 240V from that outlet, I'll just do HOT HOT GROUND and ignore neutral.... if I needed to use that on a generator, I don't needed to pigtail... or breakout..

nadogail · Oct 25, 2018

I admit to only having enough knowledge to be Certified Dangerous, so any advice I offer is guaranteed to be worth only what you have paid me for it. In fact I offer an unconditional money back guarantee; you will be refunded every cent of what I am paid for my opinions.

That being said, this is what I did when wiring my workshop 208/220 receptacle. My entrance panel is on the exterior of the garage the shop is in. I used a 50Amp three prong Range Receptacle and landed the two hots on a 50 amp breaker and the third wire onto the Neutral Buss that is also tied to Ground. I feel this is acceptable because it is the Entrance Panel, not a Sub Panel.

The 208/220 receptacle is shared by my welder and my table saw.

Your situation, location, and results may vary; but to this point it all works for me.

ishiboo · Oct 25, 2018

dogdog said:
I install all my 240v Capable outlets with 4 wire L14-30R.... it also happens to be popular with generators that has the 30Amp Receptacles... If all I wanted is 240V from that outlet, I'll just do HOT HOT GROUND and ignore neutral.... if I needed to use that on a generator, I don't needed to pigtail... or breakout..

I have several L14-30Rs for the same reason. It's great because I can use my generator cords and L14-30 -> 5-20 adapters with them.

dogdog · Oct 25, 2018

ishiboo said:
I have several L14-30Rs for the same reason. It's great because I can use my generator cords and L14-30 -> 5-20 adapters with them.

Yea my Generator came with a 30Amp L14-30P to 5-20R cord 25' super heavy... you can hang a cow off that thing just for being a 10 Gauge wires and so heavy rubber jacket...... :lol_hitti

I just figure it's more convenient...Actually for my dual voltage welder, when I wanted to use it on a 120V outlet... I have a designated pigtail to convert it from L14-30R to 5-20P, just for that welder so I don't have to unscrew stuff to switch plugs....

Augus7us · Oct 25, 2018

wyliesdiesels said:
If ALL the tools are 240v only, then why would you need 4-wire outlets?

4-wire outlets are for equipment that needs 120v AND 240v because the 4th wire is a neutral.

240v equipment does NOT need a neutral.

I'm not sure I do, that is one of the reasons I asked the question. I thought I might be missing something.

What would require both 120 and 240? Maybe I will need it, probably not if it is only something I would run into if I was using a generator.

Assuming I don't need 120 & 240, would something like this work?

https://www.homedepot.com/p/Leviton...Flush-Mounted-Outlet-Black-5207-S10/302480849

Daisy chain 3 or 4 on the same circuit in 2 gang boxes?

-Clint

mike93lx · Oct 25, 2018

I can't think of a tool that needs a 4 wire plug. Very little actually does.

I appreciate trying to think ahead, but putting in that many outlets up front, with a receptacle that doesn't match any ahop equipment seems silly. People don't generally roll around heavy duty 240v equipment. Find a spot for your table saw and leave it alone. Your dust collector is also unlikely to be moved around, same with a big planer or disc sander

Augus7us · Oct 25, 2018

dogdog said:
I install all my 240v Capable outlets with 4 wire L14-30R.... it also happens to be popular with generators that has the 30Amp Receptacles... If all I wanted is 240V from that outlet, I'll just do HOT HOT GROUND and ignore neutral.... if I needed to use that on a generator, I don't needed to pigtail... or breakout..

Was there a reason for using L14-30R aside from being the same as the generator? I'm asking because those receptacles are expensive compared to what I linked above.

The Cobbler · Oct 25, 2018

My lathe uses 120/240 so I have a 4 wire plug wired in my shop . it does give me the option to use 120@ 30 amp, 240@ 30 amp etc. glad I have it wired in the shop if I need it.

exranger06 · Oct 25, 2018

Augus7us said:
What box should I use? I assumed I could just use a 1 gang box but looking at some old threads I saw guys with one receptacle in a 2 gang box. Thinking about it this would probably be better since I'm was planning on 10/3 wire for these circuits.

240V receptacles won't physically fit in a 1 gang box. They're too wide. You need to use 2 gang boxes.

Augus7us · Oct 25, 2018

mike93lx said:
I can't think of a tool that needs a 4 wire plug. Very little actually does.

I appreciate trying to think ahead, but putting in that many outlets up front, with a receptacle that doesn't match any ahop equipment seems silly. People don't generally roll around heavy duty 240v equipment. Find a spot for your table saw and leave it alone. Your dust collector is also unlikely to be moved around, same with a big planer or disc sander

I'm trying to make sure the shop can withstand some future growth. I already have a decent number of 240v tools and I'd prefer not to move them. However if I were to buy something down the road and it would be best to rearrange a few tools to fit it in, I'd like to be able to do so without rewiring receptacles or using pigtails. I'm sure no matter what I do, I'm going to have issues down the road, just trying to avoid as many of them as possible, up front.

-Clint

dcg9381 · Oct 25, 2018

I like the 14-50 socket. Why? Probably because I have an RV and a bunch of adapters that will work with it. I've wired my welder to use the socket type and will eventually wire everything to standardize on this format.

It has the added benefit - I can run several in series electrical parallel), as each pin will easily hold 2 x 10GA wire. Meaning - I treat it like a standard wall romex run and attach more than one outlet to it. I only use one at a time...

Norcal · Oct 25, 2018

exranger06 said:
240V receptacles won't physically fit in a 1 gang box. They're too wide. You need to use 2 gang boxes.

That applies only if you use straight blade devices if locking type receptacles are used single gang boxes should be used.

Norcal · Oct 25, 2018

dcg9381 said:
I like the 14-50 socket. Why? Probably because I have an RV and a bunch of adapters that will work with it. I've wired my welder to use the socket type and will eventually wire everything to standardize on this format.

It has the added benefit - I can run several in series electrical parallel), as each pin will easily hold 2 x 10GA wire. Meaning - I treat it like a standard wall romex run and attach more than one outlet to it. I only use one at a time...

You use 10 AWG on a 50A circuit????

Bert_ · Oct 25, 2018

dcg9381 said:
It has the added benefit - I can run several in series electrical parallel), as each pin will easily hold 2 x 10GA wire. Meaning - I treat it like a standard wall romex run and attach more than one outlet to it. I only use one at a time...

I'll probably get flamed for this but I do the same thing with #8THHN all the time when wiring multiple 50A outlets.

TractorJeff · Oct 25, 2018

Norcal said:
You use 10 AWG on a 50A circuit????

He said for a welder
Maybe like this?
https://www.ecmweb.com/qampa/code-qa-45
"Stolen from another Thread"

dogdog · Oct 25, 2018

Augus7us said:
Was there a reason for using L14-30R aside from being the same as the generator? I'm asking because those receptacles are expensive compared to what I linked above.

If it is purely 240V plugs, there is no reason for neutral or L14-30R... I just like the convenience of going straight to generator when I needed it, and an available neutral wire (not shared) when I needed 120V off it on some equipment... ... they are not that expensive,

I think I got them off ebay for about $15-ish each... the R (receptacle) and the P (Plugs)... Hubbell brand, NOS.. My shop/garage is not that big, and it's a one time investment to get everything the same things IMO and some spare... they take about the same space of two gang box to install... I wire each outlet with a dedicated breaker.. but it is right next to the 120s, one EMT over to them and a 2 gang box for 120s right next (about 6") to it a 2 gang box for 240... same conduit... fits perfect. Wire in this case is not that expensive... but harder to pull after everything is set... or rather more PITA to pull an extra Neutral if I ever wants one later... rolls of flexible 10ga is only about $50-ish each x4... still plenty left

also the L14s are twist locks, that may or may not be a feature you wanted... but what ever it is, decide on one system... they get expensive and not interchangeable without pigtails and stuff...

dogdog · Oct 25, 2018

Bert_ said:
I'll probably get flamed for this but I do the same thing with #8THHN all the time when wiring multiple 50A outlets.

I thought you are not suppose to wire anything over 20AMPs to multiple outlets...(just a question, not flaming)

Bert_ · Oct 26, 2018

dogdog said:
I thought you are not suppose to wire anything over 20AMPs to multiple outlets...(just a question, not flaming)

NEC says it's fine. Supposedly if you have to follow international building code then it could be an issue. I have never ran into this though. Other parts of the country may be different. This topic is covered almost weekly it seems, there is a thread on the subject active right now.

I mainly talking about the issue (or non issue) of multiple wires under a lug.

Crazyjake8493 · Oct 26, 2018

exranger06 said:
240V receptacles won't physically fit in a 1 gang box. They're too wide. You need to use 2 gang boxes.

They do physically fit in a single gang, the dryer receptacle in my house and welder outlet in my garage are each in a single gang box. I'm not sure why they would make single gang covers for them if it wasn't allowed.

Does code prohibit this due to box fill? I'm not sure what the calculations would be for two or three 10awg conductors plus the receptacle.

dcg9381 · Oct 26, 2018

Norcal said:
You use 10 AWG on a 50A circuit????

No! I use a 14-50 socket - which, as you mention is rated for 50A. It's the "most common" type of 240V socket in my garage, so I standardize on it. These circuits (at least the ones that are electrical parallel) are on a 30A breaker. So 10GA wire. The socket is rated for more than the breaker, the wire is rated for the breaker, so the breaker is the weak link - as designed.

My welder uses 20A.
My RV - it's probably under 25A on both sides of the circuit. (actual draw)... So it'll work with this too. It's the RV that requires the neutral in my case. But having that neutral means I can pull off 120V at 30A with an adapter.
Obviously, you can only do one thing at a time, but it makes wiring a lot simpler.

As mentioned prior (and I learned on this forum) - multiple 240vs on one breaker IS allowed if it's not "residential use".

wyliesdiesels · Oct 26, 2018

nadogail said:
I admit to only having enough knowledge to be Certified Dangerous, so any advice I offer is guaranteed to be worth only what you have paid me for it. In fact I offer an unconditional money back guarantee; you will be refunded every cent of what I am paid for my opinions.

That being said, this is what I did when wiring my workshop 208/220 receptacle. My entrance panel is on the exterior of the garage the shop is in. I used a 50Amp three prong Range Receptacle and landed the two hots on a 50 amp breaker and the third wire onto the Neutral Buss that is also tied to Ground. I feel this is acceptable because it is the Entrance Panel, not a Sub Panel.

The 208/220 receptacle is shared by my welder and my table saw.

Your situation, location, and results may vary; but to this point it all works for me.

Not correct for 240v equipment according to code since a 3-wire stove receptacle is 120/240v non grounded. This is a nema 10-50.

The correct receptacle for 240v 50a equipment is nema 6-50p.

and the ratings are 240v not 220v

there is no 220v in the US.

Augus7us said:
I'm not sure I do, that is one of the reasons I asked the question. I thought I might be missing something.

What would require both 120 and 240? Maybe I will need it, probably not if it is only something I would run into if I was using a generator.

Assuming I don't need 120 & 240, would something like this work?

https://www.homedepot.com/p/Leviton...Flush-Mounted-Outlet-Black-5207-S10/302480849

Daisy chain 3 or 4 on the same circuit in 2 gang boxes?

-Clint

No thats the wrong outlet. That is a non-grounded 120/240v outlet. aka nema 10-30

You need a nema 6-30 which is a grounded 240v outlet.

dcg9381 said:
No! I use a 14-50 socket - which, as you mention is rated for 50A. It's the "most common" type of 240V socket in my garage, so I standardize on it. These circuits (at least the ones that are electrical parallel) are on a 30A breaker. So 10GA wire.

My welder uses 20A.
My RV - it's probably under 25A (dual) sides... So it'll work with this too.
Obviously, you can only do one thing at a time, but it makes wiring a lot simpler.

As mentioned prior (and I learned on this forum) - multiple 240vs on one breaker IS allowed if it's not "residential use".

The NEC has no such prohibition even in residential use.

Bert_ said:
NEC says it's fine. Supposedly if you have to follow international building code then it could be an issue. I have never ran into this though. Other parts of the country may be different. This topic is covered almost weekly it seems, there is a thread on the subject active right now.

I mainly talking about the issue (or non issue) of multiple wires under a lug.

You cannot put multiple wires under a lug unless its listed and rated for multiple wires.

dcg9381 · Oct 26, 2018

wyliesdiesels said:
The NEC has no such prohibition even in residential use.

It's not an NEC prohibition.
To me, it's a "resale" issue with inspectors - perhaps - but I'm being conservative.
It's IRC E3702.5

wyliesdiesels said:
The correct receptacle for 240v 50a equipment is nema 6-50p.

Agree. Another "correct" plug is 14-50P, which gives you the neutral and some "adapter" options out of the RV section. It also seems to be standard on dryers, EV plugs, and RVs.

wyliesdiesels · Oct 26, 2018

dcg9381 said:
It's not an NEC prohibition.
To me, it's a "resale" issue with inspectors - perhaps - but I'm being conservative.
It's IRC E3702.5

Agree. Another "correct" plug is 14-50P, which gives you the neutral and some "adapter" options out of the RV section. It also seems to be standard on dryers, EV plugs, and RVs.

Dryers use 14-30 not 14-50...

Norcal · Oct 26, 2018

Why do folks get so orgasmic over having a neutral for 240 volt equipment?

Bert_ · Oct 26, 2018

wyliesdiesels said:
You cannot put multiple wires under a lug unless its listed and rated for multiple wires.

Better not tell that to the outlets in dozens of shops I've wired this way, might burn down tonight if they knew...

Most of those shops have 10-50's too :shocking:

I shouldn't advocate doing it "wrong" but I do get tired of the code nazi attitude. I have never met an inspector as strict as many on this forum. Most of the time it more common sense then to the letter of the code.

For instance shoving a #6 and a #10 solid in the same lug would not be good since unlikely you'll get even pressure on each wire. But with two wires of the same size especially stranded it just has never been a problem.

wyliesdiesels · Oct 26, 2018

Bert_ said:
Better not tell that to the outlets in dozens of shops I've wired this way, might burn down tonight if they knew...

Most of those shops have 10-50's too

I shouldn't advocate doing it "wrong" but I do get tired of the code nazi attitude. I have never met an inspector as strict as many on this forum. Most of the time it more common sense then to the letter of the code.

For instance shoving a #6 and a #10 solid in the same lug would not be good since unlikely you'll get even pressure on each wire. But with two wires of the same size especially stranded it just has never been a problem.

Do it right or dont do it at all.

If we dont care about all of the code then why bother with any of it?

dogdog · Oct 27, 2018

Norcal said:
Why do folks get so orgasmic over having a neutral for 240 volt equipment?

Well Neutral can turn it to a multipurpose instead of a single purpose...

sberry · Oct 27, 2018

I have never needed to change a welder outlet to 4 wire for another appliance. There are exceptions for welders, never seen them for a 14-50 no matyer how common they are in your garage.
I havnt always been perfect, still have a coue code violations to fix regarding plugs from old stuff but wr grmerally font advocate poor practice. 14-50 are for ranges and heavy wire, true 50a

alfredeneuman · Oct 27, 2018

sberry said:
matyer, havnt, coue, wr grmerally font .

Huh?

sberry · Oct 27, 2018

alfredeneuman said:
Huh?

Phone auto shate.

gtae07 · Oct 28, 2018

Norcal said:
Why do folks get so orgasmic over having a neutral for 240 volt equipment?

I ran 6/3 to a 14-50 in my shop. I'm glad I did, because I was able to take our old oven and plug it in out in the shop so I can bake paint onto parts. Did the same in the garage because I had enough left over wire, and now I could power a car charger (if we go electric) or an oven/kiln if my wife gets into ceramics.

I also use the same outlet for my welder and plasma cutter, with an adapter cord.

Did I need that neutral? No, and I probably could have gotten away with undersized wiring by calling it welder use only. But for a few more dollars I added additional capability and I've now made use of that capability productively.

Who knows what else I might use in the shop in the future...

sberry · Oct 28, 2018

I shouldn't advocate doing it "wrong"

I agree.

sberry · Oct 28, 2018

I learned code from these forums and the code Nazis. It took me a while and I studied pretty intently answering questions and reading for about a year under John Nelson and Warren Goodrich on DIY and some with Bob Keis on ETF. My design and installation skills were good enough that a lot of people didn't know I didn't oknow, did a lot of things wrong back in my younger days for a long time, even went back to a few local jobs I did and fixed a couple things. \
The code guru types on forums are really good, I always have to comment when someone suggests finding a local guy to learn from vs the collective wisdom of a forum like this where there are several masters and it gets sorted out. The beginner doesn't know if the guy doing the teaching really knows in some cases, most are great but also have seen my fair share of guys with the paper in their pocket aint worth a shate and some of the worst work is done by them, some of the very best by hobby/part timers too.

sberry · Oct 28, 2018

I try not to forget who I am talking to on these forums and remember that my experience may not always apply or be relevant to the poster, this is a bit more true with welding where not everyone needs an SA400 and has to learn the way I did to do simple hobby work, I try not to let some of the experience get in the way of simple advice.
But,,, I also am willing to share and most of it that stands out to me is in the area where I have changed my mind and some of the long term experience has proved itself out contrary to the speculation I based some of the early design on.
The compulsive worry about pressure drop, line size, extra pipe and wire has cost me a lot of money effort and worry for stuff that never proved out. I have never longed for a larger pipe I ran to a light so I could run wire down it for a welder circuit, never needed to convert a welder outlet to an oven one, never overheated a 10 wire on a welder, havnt suffered v drop on typical 120V circuits and found the real load to be closer to 10A than the 20 that the breaker is.

Found out that a 1/2 air line would have worked as well as the inch I ran on the first one and the list for this is long compared to the "I should have" which is rare and few and any extra work would have been way easier than all I did the first time to future proof it. By the time I needed new or extra the design and the technology had changed, needed a new route, different wire or none at all. Could have used 2 circuits in my storage vs the 10I have and some have NEVER been used, lots of wire parked snuggly for a long time "just in case" and would have been easier and cheaper to cross some of the bridges when I came to them.
This is why Norcal made the comment about the neutral,,, its so rare that a circuit needs to be converted that there are millions of pounds of copper and dollars parked in the walls all over the country and a good chance there are other aspects of the circuit design that make it impractical for additional circuits.
Some of the best I did was where I wired as I went as needed, saved a lot compared to where I plan it all in advance that may not have turned out exactly right in the end anyway,,, especially in shops.

TractorJeff · Oct 28, 2018

gtae07 said:
I ran 6/3 to a 14-50 in my shop. I'm glad I did, because I was able to take our old oven and plug it in out in the shop so I can bake paint onto parts. Did the same in the garage because I had enough left over wire, and now I could power a car charger (if we go electric) or an oven/kiln if my wife gets into ceramics.

I also use the same outlet for my welder and plasma cutter, with an adapter cord.

Did I need that neutral? No, and I probably could have gotten away with undersized wiring by calling it welder use only. But for a few more dollars I added additional capability and I've now made use of that capability productively.

Who knows what else I might use in the shop in the future...

In another thread, I offered the same advice 6-3 instead of 6-2.
Most were not happy about it? Electric oven, ceramic kiln were the 2 suggestions I had on the re-sale end. Didn't think of the EV. :beer:

sberry · Oct 28, 2018

They probably didnt need 6 in the first place,,, ha

dcg9381 · Oct 29, 2018

sberry said:
The code guru types on forums are really good, I always have to comment when someone suggests finding a local guy to learn from vs the collective wisdom of a forum like this where there are several masters and it gets sorted out. The beginner doesn't know if the guy doing the teaching really knows in some cases, most are great but also have seen my fair share of guys with the paper in their pocket aint worth a shate and some of the worst work is done by them, some of the very best by hobby/part timers too.

I've seen electrical forms where they aren't even allowed to respond to a "homeowner" post - probably due to liability. And it's unfortunate, especially as you've got the collective wisdom of 20 code nazis that are literally sitting around arm-chair taking apart installs. Simply posting a photo of an install, gathering all the "did this wrong" comments save tons of time and money over having the local power company come out and go through inspections.

And look, I get that you probably shouldn't teach this stuff to everyone and it can be dangerous. But hell, real "electricians" around here - I'm seeing crews making some pretty basic mistakes, so I'm not sure that local help is always the right answer.

Tmsboss · Oct 31, 2018

I just installed 5 each 30 amp 220v circuits in a commercial kitchen. The Chef, got to love chefs, knows he wants 5 outlets for present and future requirements. The convection oven he has ordered has a 6-30 plug. He has no,idea what future requirements he will have. He insisted on 30 amp circuits. I pulled in 10-3 with a ground. The white, common conductors are in the two gang boxes Incase it’s needed in the future. A whole lot easier to leave the common in the box than pull another wire later. Receptacles are $30.00 or less. Change as needed.

Standard 240v 30amp Receptacle

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