240V receptacle preferences? And a boo-boo confession...

[Jack Llewyllson]

Hello, Crickers:

I'm getting a little bit wrapped around the axle with my wiring.

First the good news: shop is erected, sheathed, roofed, sided, and mostly caulked. Walk-in door is installed, but needs latch set mounted. Garage door due a week before Christmas. Walls are still open, as it just passed its electrical rough-in inspection. Electrical trim just hit the top of the list.

So today, I cheerfully opened my wiring device order, looked around the new space for a final as-built count, and realized I roughed the 240V stations (all 19 of 'em, on two circuits) into single-gang boxes.

D'oh!

This leaves me with two questions, one important and the second likely futile:

1. Is there a consensus choice of 240 receptacle types among woodworkers? I've typically used 20A single outlets on 12 AWG romex in a 4s box, but I've got a boxful of 30A breakers mounted so I won't (also _can't_, per NEC, AFAIK) connect 20A outlets to those circuits. So what works well for folks? I've also run NEMA L630Rs in the past, albeit at con$iderable co$t.

I'll have about four outlets (table saw, dust collector, planer, future upgraded lathe) semi-permanently connected. The balance are for layout flexibility, future changes, etc., and may indefinitely stay wired straight through with blank faceplates. I'm hoping not to open my walls for quite some time after they're paneled up.

2. Is there, in fact, a 240V 30A outlet generally available that would fit neatly into a 1G box? I mean, I don't THINK so... but the one thing I'm certain of is that I don't know everything.

Thanks for your indulgence of a non-electrician.

Cheers,

Jack

[ray grundhoefer]

250 volt 30 amp power outlet 6-30R will fit a single gang box. Or a 30 amp 250v twistlock rec

[Mike Henderson]

If you put in 30 amp breakers I think you should use 10 gauge wire. 12 gauge wire is only good to 20 amps (if I recall correctly).

Mike

[Also, I think they make a four pin receptacle for 30 amps, in case you need to bring out the neutral. It's used for electric clothes dryers.]

[Jack Llewyllson]

If you put in 30 amp breakers I think you should use 10 gauge wire. 12 gauge wire is only good to 20 amps (if I recall correctly).

Thanks, Mike. Happily, that part I got right -- my 120V are wired with 12 gauge for 20 amps, and the 240s with 10-gauge.


[Also, I think they make a four pin receptacle for 30 amps, in case you need to bring out the neutral. It's used for electric clothes dryers.]

Four-wire is probably also great for grand, world-conquering Felders, but those aren't in my budget if I ever want to pay off this shop. :D

[Paul F Franklin]

With 30 amp breakers you need to run 10 ga. You may find a 30 amp receptacle that can mount in a single gang box, but you likely will exceed the allowable box fill, especially if you run neutrals and especially if you daisy chain the circuit, meaning you have 3 wires entering the box and 3 wires exiting the box to go to the next receptacle.

Here's a decent box fill calculator that will tell you how many cubic inches you need for different scenarios: https://www.constructionmonkey.com/calculations/electrical/boxfill

But even if you can meet the box fill requirements, it's going to be a *^*&( to wire. As painful as it might be, I'd rip them out and put in 4" deep boxes.

[Jim Becker]

All of my 240v receptacle in my shop are twist locks and amperage specific. The 30 amp versions do benefit from a "more generous" box, IMHO. The 10 gage wire is quite stiff and harder to bundle up neatly in a really tight space. I honestly like at least deep boxes for almost any application, not just 240v terminations.

[Anthony Whitesell]

I'm with Jim. All of my 240V outlets are twist lock 250V 20A. I like have the super obvious differentiation between the 120V outlets and the 240V.

[Charlie Velasquez]

With 30 amp breakers you need to run 10 ga. You may find a 30 amp receptacle that can mount in a single gang box, but you likely will exceed the allowable box fill, especially if you run neutrals and especially if you daisy chain the circuit, meaning you have 3 wires entering the box and 3 wires exiting the box to go to the next receptacle.

Here's a decent box fill calculator that will tell you how many cubic inches you need for different scenarios: https://www.constructionmonkey.com/calculations/electrical/boxfill

But even if you can meet the box fill requirements, it's going to be a *^*&( to wire. As painful as it might be, I'd rip them out and put in 4" deep boxes.
This....

Leviton has the specs for that 6-30R having a volume of about 8 cu. inches, then the wires, pigtail for the ground, not sure if that receptacle is rated for two wires at the terminals, else you have a red and a black pigtail. My calculations have the fill at about 23+ cu inches with only the ground pigtailed.
But that may be moot Leviton has the width as 52mm wide. That exceeds the NEC limit of 50mm for a single gang device, by just a tad. It will physically fit in the box, ....but....

[Tom Bain]

Here is an out of the box idea ... what about surface mounting a 4” square box in front of the single gangs to give you extra room for the wiring? I don’t think that violates code but I’m not an expert on those particulars.

[John Lanciani]

You said the walls are still open, just bite the bullet and replace the boxes.

[David M Peters]

I'd also vote for switching everything out to 4" square boxes. The guys who wired my shop did everything with "4 squares" (as they called them) and it has made it a lot easier to modify after the fact. Even the light switches are 4" boxes - no stuffing & twisting, just simplicity.

[Jack Llewyllson]

250 volt 30 amp power outlet 6-30R will fit a single gang box. Or a 30 amp 250v twistlock rec

Cool; thanks. I'll give one a try, but I don't value my chances of stuffing it in there with daisy chain pigtails.

[Bob Riefer]

You said the walls are still open, just bite the bullet and replace the boxes.


In my opinion, this. Easy to do now while the walls are open, I can't imaging it's hundreds of boxes to change out... you'll be done box swappin' in 20 mins.

[Jack Llewyllson]

Okay, I'm pretty well settled on this one: 1G boxes are coming out. I knew better in the first place, but wasn't thinking fast. I'll plan to replace with the same type boxes used for my 120V double duplexes with 2 circuits, which are the extra-capacity blue Carlons with 48.2 cu. in. capacity. That gives me room for stiff fingers to wrassle the stiff romex.

Re outlet types: is the consensus choice to use twist locks? I have done that once before, and thought it worked well in practice.

One thing I'd rather NOT do is replace the pricey breakers, which are at 30A. I believe that NEC requires 30A-rated outlets due to breaker sizing, which may herd me into using L6-30R twisties. The straight blade 250V 30A outlets don't seem to be as commonly available near me.

[Bill Dufour]

If you happen to find some matched twist lock cord ends snap them up. Do not worry about amps or 3 or 4 wire. When I work on a big machine I cut the motor cord and install a twistlock set. Cut cord as close to the motor as possible then install new short cord into the motor on the bench. Makes any trouble shooting much easier as well as motor work like bearings etc.
Bil lD

[Alex Zeller]

By code only 15a 120v receptacles can have multiple outlets on one run. If you have stationary equipment this isn't too much of an issue. If you move your tools around it usually means lots of cords. If you have 30 amp breakers then everything downstream from it also needs to be rated for 30 amps. If you choose not to follow code I recommend you make it so you can easily remove it if you sell your shop. I personally have two 30 amp runs with multiple 30 amp outlets because I know that I'll never use both receptacles at the same time. I also have short pigtails with a 30 amp plug and a 20 amp receptacle inside a metal box so I don't need to put 30 amp plugs on all my tools. But I'm a hobbyist and the only person who works in my shop.

[Tom M King]

I've had Hubbell receptacles, plugs, and cord ends in service for so long, that I forget which model they are. I did like Bill, and have a short tail on each tool. I have a fair number that have been in service since the mid 1970's. I did destroy one end, but that was because I forgot to unplug it before I drove off in the tooltruck stepvan. I sold that truck in the early 1990's. It was a 1970 model. I outgrew it.

[John Lanciani]

By code only 15a 120v receptacles can have multiple outlets on one run.

Can you provide a citation for this? I’m 99% sure that it is incorrect but my 2020 NEC book is 10 miles away.

[Frank Pratt]

By code only 15a 120v receptacles can have multiple outlets on one run.

This is the first time I've heard this rule. Can you tell us where it is, because I don't think that's right?

[Charlie Velasquez]

This is the first time I've heard this rule. Can you tell us where it is, because I don't think that's right?

Multiple receptacles are allowed in most cases, both 120 v and 240 v. There are some cases where a single dedicated outlet is required, as in a sump pump installation. There are some cases where multiple outlets are required, as 15 amp receptacles on a 20 amp 120 volt circuit breaker.
NEC 210.20’s discuss cases where branch circuits have multiple receptacles.

[Jack Llewyllson]

By code only 15a 120v receptacles can have multiple outlets on one run.

Nope. Despite the popularity of that opinion, I've found nothing in the NEC to support it. I believe this statement is incorrect.

I'm also quite certain that this topology is not a safety hazard in my shop. I'll never run more than two pieces of equipment at the same time, defined as (machine) + dust collector. The heaters are also on 240V, but they have their own 30 A circuit (both share a 30A circuit; they draw 3.8 amps each).

Also, I've run 2 ea., parallel, 240V tool circuits to make it easy to separate dust collection draw from tool draw. So if I'm running the planer, for instance, it'll be pulling from circuit "A," with the DC drawing from circuit "B."

Furthermore, it's not like the circuits are unprotected fire starters. Both of the tool circuits have circuit breakers in case of overload.

Overloading 30A circuits with my cute little tools is frankly unlikely. I could run the saw (12.8 amperes) and the planer (11.51 amps) on the same circuit, at the same time, provided I didn't start them simultaneously. If, however, I somehow managed to use up the circuit's ampacity, its breaker should trip well before the 10-gauge wire heats up in the wall.

Finally, while there are certain home-level use cases (e.g. water heaters and jacuzzis) where dedicated circuits are called out in the code, shop tools don't fall into that category AFAIK. The two inspectors who've looked over the rough-in so far didn't seem to think so, either -- and I asked. Better to get caught early than blow the sign-off when victory is in sight.

This dedicated circuit idea is a canard that everyone has heard, and which many believe. Not being an electrician myself, I spent a fair amount of time chasing it down to either confirm or debunk. I'm pretty confident that it's an authentic -sounding rumor, not a fact.

But don't take my word for it. I'm not an electrician. :)

[Bill Dufour]

Off the top of my head a refrigerator outlet must be the only one on that circuit and a washing machine may be on a non GFCI circuit. I do not think a dryer can run off that same non GFCI circuit unless it is at least 6 feet from a sink and the washer?
240 outlets can have multiples on one circuit. I think for 120 it is 12 receptacles per circuit maximum.
Bill D

[Marc Fenneuff]

I really like twist-locks and made up a couple pigtails for when I need to directly plug-in a vac or powered hand tool. I have them for my 120V and 240V tools.

[Bruce King]

The most recent locations where GFI is required is the dishwasher and laundry area.
If a dishwasher is hard wired, the circuit breaker has to be GFI. This is due to the finding that all the dishwasher fires start as current leakage that a GFI will trip on. Some new dishwashers might have an internal GFI with the reset at the lower front. The circuit still needs one too since no one knows which unit will be installed. Many houses have a wall switch for the dishwasher, this was the 1980’s effort to stop some dishwasher fires. All idle dishwashers should have the switch off or the door cracked open for safety. These units are total garbage when it comes to internal wiring safety.
The language about 6 feet has been changed or just left out to require GFI in those areas even if more than 6 feet from water. Different areas of the country are way behind on code cycles. When they finally update it might jump up two cycles.

[Alex Zeller]

Sorry I got distracted. What I was trying to say was using multiple lower rated receptacles on a circuit isn't allowed by code. You are allowed to do it on a 20 amp 120v circuit but not allowed to use any receptacle less than what the circuit is rated for. You can have multiple if they are all rated the same.

[Frank Pratt]

Sorry I got distracted. What I was trying to say was using multiple lower rated receptacles on a circuit isn't allowed by code. You are allowed to do it on a 20 amp 120v circuit but not allowed to use any receptacle less than what the circuit is rated for. You can have multiple if they are all rated the same.

That's much better, thanks.

[Michael W. Clark]

I'm not an electrician, but thinking through this, I would not not want a circuit where I have a 20A breaker, 15A circuit wire (14GA?), and multiple outlets. In this scenario, I could plug in (2) 10A loads, and exceed the wire capacity without tripping the breaker. This would be an "unfortunate" situation with wire buried in the wall.

IMO, for a shop, make it all surface mount as needs will change as you add/subtract equipment.

[Jim Becker]

Michael, there's more risk of what you describe with 120v circuits than with 240v circuits in most single woodworker shops. As long as the DC and compressor are on dedicated circuits separate from other machines, it's unlikely that someone is going to run two 240v tools simultaneously simply because their arms are not long enough or they don't have enough of them. :)

I agree relative to surface mount, particularly for 240v circuits and wish I would have done that initially in my shop Moving things around was more complicated because of that. Anything I've added in the last x number of years has been surface mounted, such as my CNC machine, for that reason. Faster installation and faster/easier changes.

[Mike Henderson]

I'm not an electrician, but thinking through this, I would not not want a circuit where I have a 20A breaker, 15A circuit wire (14GA?), and multiple outlets. In this scenario, I could plug in (2) 10A loads, and exceed the wire capacity without tripping the breaker. This would be an "unfortunate" situation with wire buried in the wall.

IMO, for a shop, make it all surface mount as needs will change as you add/subtract equipment.

I don't know about others but I used 12 gauge wire when I wired up my 120V outlets.

In any case, my understanding is that the wire should match the breaker. So if you put in 20 amp breakers you should use 12 gauge wire.

Mike

[Paul F Franklin]

I'm not an electrician, but thinking through this, I would not not want a circuit where I have a 20A breaker, 15A circuit wire (14GA?), and multiple outlets. In this scenario, I could plug in (2) 10A loads, and exceed the wire capacity without tripping the breaker. This would be an "unfortunate" situation with wire buried in the wall.

IMO, for a shop, make it all surface mount as needs will change as you add/subtract equipment.

You are not allowed to have 14 ga (15 amp) wire with a 20 amp breaker, that's not what an earlier post said. What you are allowed to have are multiple 15 amp receptacles on a 20 amp circuit. The circuit must be wired with 12 ga wire; only the receptacle device is allowed to be 15 amp rated. There is no danger of overload in that situation because a single load that draws more than 15 amps must have a 20 amp plug that won't plug into a 15 amp receptacle. So the receptacle is not overloaded. And multiple smaller loads connected to different 15 receptacles that together draw more than 20 amps will trip the breaker. So the wire is never overloaded. There is nothing to prevent you from using only 20 amp receptacles on a 20 amp circuit (they will accept standard plugs as well as 20 amp plugs), but the code recognizes that most household loads are far less than 15 amps and allow the 15 amp receptacles (which are a little less expensive).

[Charlie Velasquez]

I don't know about others but I used 12 gauge wire when I wired up my 120V outlets.

In any case, my understanding is that the wire should match the breaker. So if you put in 20 amp breakers you should use 12 gauge wire.

Mike

Or larger... I had spools of 10awg from another project. All my 20 amp and 30 amp circuits in my shop are 10awg.

But as was mentioned earlier, there are specific cases, usually involving motors, where over-sized breakers are allowed. For instance, a dedicated circuit supplying a 2hp motor can run a 14awg wire and theoretically a 30 amp breaker.

[Michael W. Clark]

For some reason I thought we were talking about 120V and I think I misread one of the posts. Totally agree breaker should be rated to protect the wire.

For 240V, I put my air compressor and dust collector on dedicated circuits since they can run at the same time as other tools. I like the twist locks too.

[Rollie Meyers]

With the 2020 NEC, 240V receptacles will require GFCI protection, even clothes dryers, and outdoor A/C condensing units, 8 States have adopted it as of this writing, WA,WO,CO,TX,SD,MN,GA, & MA, who was the first to adopt.

https://www.mikeholt.com/necadoptionlist.php

[Mike Henderson]

With the 2020 NEC, 240V receptacles will require GFCI protection, even clothes dryers, and outdoor A/C condensing units, 8 States have adopted it as of this writing, WA,WO,CO,TX,SD,MN,GA, & MA, who was the first to adopt.

https://www.mikeholt.com/necadoptionlist.php

What about things that are directly connected and don't have a receptacle?

I guess that means a breaker with GFCI because there are so many different 240 volt receptacles. Hard to imagine all of them having a GFCI version.

Mike

[Jim Becker]

I guess that means a breaker with GFCI because there are so many different 240 volt receptacles. Hard to imagine all of them having a GFCI version.


Yup...at the breaker. Same for AFCI.

[Tom Bain]

Anyone looked at how much those 240V GFCI breakers cost! :eek: I would hope the price comes down if that becomes a widespread code requirement. Holy cow.

[Mike Henderson]

Anyone looked at how much those 240V GFCI breakers cost! :eek: I would hope the price comes down if that becomes a widespread code requirement. Holy cow.

From what Rollie posted, it's only receptacles. You could avoid the GFCI by directly connecting your 240 volt tools.

Mike

[Michael W. Clark]

From what Rollie posted, it's only receptacles. You could avoid the GFCI by directly connecting your 240 volt tools.

Mike

If you direct connect, you probably want to consider some type of disconnect for blade changes. I don't like to trust the on/off switch, I like to unplug when possible. My TS is direct wired and has a disconnect that I turn off for blade changes.

[Mike Henderson]

If you direct connect, you probably want to consider some type of disconnect for blade changes. I don't like to trust the on/off switch, I like to unplug when possible. My TS is direct wired and has a disconnect that I turn off for blade changes.

Good idea. However, I feel comfortable turning the switch off on my SawStop when I change blades.

Mike

[Michael W. Clark]

Good idea. However, I feel comfortable turning the switch off on my SawStop when I change blades.

Mike

Personally, I'm afraid I will accidentally hit the tool button to start it. My start button for the TS is very close to my hip when leaning in to change blades. I'm over particular on the router table and bandsaw too. For some reason the drill press doesn't bother me as bad but I still unplug it most of the time.

[Mike Henderson]

Personally, I'm afraid I will accidentally hit the tool button to start it. My start button for the TS is very close to my hip when leaning in to change blades. I'm over particular on the router table and bandsaw too. For some reason the drill press doesn't bother me as bad but I still unplug it most of the time.

The SawStop has a switch to turn power on and off, but that does not cause the blade to spin. There's a separate paddle to get the blade to spin. Additionally, if you did trip the paddle while you had your hand on the blade, the saw would give you an error code and not start.

So given all that, I turn the switch off and change the blade.

Mike

[Frank Pratt]

Anyone looked at how much those 240V GFCI breakers cost! :eek: I would hope the price comes down if that becomes a widespread code requirement. Holy cow.

They are obscenely expensive, but with increase production, the prices will go down. It happened with the single pole GFCIs & AFCIs as they were mandated for more widespread use.

If you are in immediate need of a 2 pole, 40, 50, or 60A GFCI breaker, look at getting a spa panel, which comes with the GFCI breaker in it & they're significantly cheaper than buying just the breaker.

[Michael W. Clark]

The SawStop has a switch to turn power on and off, but that does not cause the blade to spin. There's a separate paddle to get the blade to spin. Additionally, if you did trip the paddle while you had your hand on the blade, the saw would give you an error code and not start.

So given all that, I turn the switch off and change the blade.

Mike

Thanks Mike, that makes sense. My TS is a Grizzly 1023 with mag starter, so if I were to touch the start button with my hip, the blade starts. I do have a knee kick for stopping the saw and it makes the start button harder to hit by accident.

[Charlie Velasquez]

With the 2020 NEC, 240V receptacles will require GFCI protection, even clothes dryers, and outdoor A/C condensing units, 8 States have adopted it as of this writing, WA,WO,CO,TX,SD,MN,GA, & MA, who was the first to adopt.

https://www.mikeholt.com/necadoptionlist.php

It should be noted that 210.8 does not mandate all 120 and 240 volt receptacle be gfci. If your shop is a stand-alone building that does not service cars and the like, you probably do not have to worry.
Shops whose floors are higher than grade level are not subject to the change. So probably includes most with wood floors and slab on grade construction, not set into a hill.

[Bruce King]

Thanks Mike, that makes sense. My TS is a Grizzly 1023 with mag starter, so if I were to touch the start button with my hip, the blade starts. I do have a knee kick for stopping the saw and it makes the start button harder to hit by accident.
The start button should be flush with the bezel and require pushing at least 3/16 before starting so bumping it does not cause a problem. If not I would ask them for the correct switch.

[Mike Heidrick]

All the answers are prob here. I used all L6-30r, Hubbell, I use all 10ga romex orange, and all 30amp CBs. I put L6-30 plugs on all my single phase 220 tools that are 30 amp fla or less motors. Perfect since doing that starting in 2005. Not long but I did it in my new shed too.

[Ronald Blue]

I have all my 240 volt outlets wired with 8 gage in conduit so THHN and 30 amp breakers. Then using the Hubbell L6-30 series plugs and receptacles. If I add a machine that needs more than 30 amps it's just a breaker change and receptacle. The wire is already sufficient to handle the load.

[Charlie Velasquez]

I used 10 awg for 30 amp, but as you did, and many said using conduit makes future changes a breeze. In my case, five days after I had "finished" wiring my shed I decided to add a receptacle to the exterior near my neighbors so they could run an extension cord and use my generator power during a power outage.
Took all of 45 minutes from walking in the shed to putting the cover on the box.

[Alex Zeller]

If worried about a tool being directly wired and how to safely shut it off you can always buy a Lock Out Tag Out device for the breaker. A lot cheaper than buying a knife switch. I don't know all the rules as to when a knife switch is needed in a business (I think it has to do with how close the breaker is or it could be the code has changed as we have them on some tools where I work) but for a hobbyist the correct loto would work just fine.

[Frank Pratt]

If worried about a tool being directly wired and how to safely shut it off you can always buy a Lock Out Tag Out device for the breaker. A lot cheaper than buying a knife switch. I don't know all the rules as to when a knife switch is needed in a business (I think it has to do with how close the breaker is or it could be the code has changed as we have them on some tools where I work) but for a hobbyist the correct loto would work just fine.

Code here requires that the disconnect means (a knife switch is just one type of disconnect) be located within sight of and within 9 m of the motor, unless it is capable of being locked in the open possition.

[Jack Llewyllson]

I have all my 240 volt outlets wired with 8 gage in conduit so THHN and 30 amp breakers. Then using the Hubbell L6-30 series plugs and receptacles. If I add a machine that needs more than 30 amps it's just a breaker change and receptacle. The wire is already sufficient to handle the load.

That's beast-y. Well done!

Not sure I've the budget or the patience for that program (nor are my needs that high-end). I did wire in a single 6-50R outlet on 6-gauge to handle a welder.

[Jack Llewyllson]

If worried about a tool being directly wired and how to safely shut it off you can always buy a Lock Out Tag Out device for the breaker. A lot cheaper than buying a knife switch. I don't know all the rules as to when a knife switch is needed in a business (I think it has to do with how close the breaker is or it could be the code has changed as we have them on some tools where I work) but for a hobbyist the correct loto would work just fine.

In my case, I opted for a consumer-grade solution: the power circuits (3 x 120V and 3 X 240V) are each wired through heavy-duty light switches. Those are set ~80" above the floor, where my wife can _just_ reach them and little kids can't.

[Jack Llewyllson]

Hello, Crickers:

I'm getting a little bit wrapped around the axle with my wiring.

Thanks to everyone who replied here.

For anyone still following this post, here's what happened: I ordered up half a dozen of L6-30R receptacles (Leviton, as it happens) to see how they'd fit in deep, single-gang boxes.

I also picked up a couple of boxes of WAGO lever-nut connectors, which I hadn't used before. The 613-221 size fits 10-gauge wire! They're a short learning curve (dead simple, really), and are both easier to wrestle with and much smaller in the box than a wire nut sized for a 10-gauge, three-conductor pigtail. They hold the wires FIRMLY, although I taped 'em anyway. The WAGOs are also reversible and reusable. Best of all, no plier-twisting required!

After installing a couple of twist-locks and testing them, I'm satisfied that the outlets will fit in the present boxes with no issues. Other than adding a 6-gauge welding outlet (just because), that completes my shop wiring scheme for now.

Hope everyone had a fine holiday.