220 Volt shop outlets

[Steve Roxberg]

None of my current 220 tools in the shop use/need a 30 amp circuit. They all run on a 20 Amp individual circuit and I haven't ever had a problem. The run length is short, under 50 feet at most so that helps I'm sure.

Current 220 tools include SawStop, Planer, Jointer, and Dust Collector. None of these will be upgraded that I'm aware of since I'm happy with all of them.

I don't own a big compressor and might like one but don't have a need today.

What tools might I need up with that would/could require 30 amp.

I ask the question because I'm wiring the shop and then dry walling it. Trying to decide if I should run 10 - 3 instead of 12 - 3 to hand any future increase in need. I'd probably reuse my 20 amp breakers and outlets since they work. The only advantage would be the ability to convert any of those outlets to 30 amp if I needed.

Any thoughts on ways to future proof a wiring job? I have no clue where to put the outlet if it is a new tool, so maybe I'm over thinking this. I tend to do that.

Thanks in advance for your advice.

[Jerry Bruette]

Since you're doing the whole shop why not put your wiring in conduit, on top of your drywall? Could make it easier to add or move outlets in the future.

[Ole Anderson]

240 v-20 amp is good for 3 hp, so unless you anticipate something bigger, you are good. What tools need a 30 amp 240 v circuit? An upgrade to a 5 hp dust collector, which you say you don't need. A welder? A wide belt sander? But those might need even more than a 30 amp circuit. If you can stand dealing with 10 gauge copper, just run everything 30 amp if you anticipate staying at no more than 5 hp. If you can locate a subpanel in the shop, surface mounted, you have the ability to run any future circuits in conduit on the surface as Jerry suggested.

[Mike Henderson]

I ran 12/2 for all my 240V outlets before I put up the drywall. If I had to do it over again, I'd probably run 10/2 just because the cost wouldn't be that much more.

I only have one machine that I had to put in 10/2 (5 HP machine) after I put up the drywall, however. And that's been over maybe 6 years in the shop.

Mike

[John K Jordan]

I have a 5hp cyclone DC and a 5hp air compressor. Some people use table saws with big motors. I also use several welders and a plasma cutter that each take a 50 amp circuit. I don't know of anything else in a shop that would need wire for over 20 amps.

For all my 20 amp 220 circuits I ran 10-2/g in case I needed it later. The difference in cost of materials was not significant.

JKJ

[Ben Rivel]

As others have said unless you plan on running over a 3HP motor on anything you dont need anything more than 20 amp circuits. If you are really worried about it though, maybe wire one 30 amp circuit up and put an outlet for it on each side. That way you'll be prepared should you ever need it.

[Wade Lippman]

Grizzly 3hp Cyclones are 30a.
10/2 is not a big deal, I ran 6/3 for my subpanel and 8/3 for my generator. Better to run it while it is convenient then when you find out you needed it.

Actually Grizzly calls for 40a, but I don't think anyone does that.

[Jon Endres]

I'm currently wiring my shop. All of my 240v stuff will be wired with 12 ga stranded THHN in 3/4" EMT, surface mounted, with NEMA 6-20R receptacles and plugs. My biggest machine motor is a 3-hp Unisaw, and even that came with a 15-amp plug on the cord. Every other 240v machine is 2-hp or less, jointer, bandsaw, dust collector, air compressor, radial arm saw. My longest wire run, up the wall, across the ceiling and back down the wall will probably max out at 65 feet. I will be installing a receptacle for a welder but that will be wired with appropriate gauge copper wire. I got my wire really cheap off craigslist, but even if I had to pay full price, I probably wouldn't have changed the plan. I also was going to use twistlocks, but haven't yet found an advantage for those.

[Bill Arnold]

When I wired my shop, I wanted to do it one time. So, I ran 10-2 w/g to all 220V outlets, putting at least one on each wall whether I had a tool there at the time or not. Each wall also has its own 110V circuit run with 12-3 w/g. It might sound like overkill but, as I said, I only had to do it one time.

[Larry Frank]

When I had my shop and garage wired, I had all the wiring done for 30 amp circuits. The extra cost was not very much. I recently got a 5 hp cyclone that needed 30 amps and was easy to change a breaker and outlet.

[Steve Roxberg]

Just confirming that I will run 10/2 with a ground. Is that correct?

[Jim Becker]

Just confirming that I will run 10/2 with a ground. Is that correct?
Correct for general machinery circuits of up to 30 amps. (can also be used for 20 amp circuits as a hedge for future compatibility with 30 amp demands if the breaker and terminations are changed appropriately)

[Chris Padilla]

10/2 w/ground is fine but you might consider 10/3 w/ground (the w/ground is implied, BTW...so just 10/2 or 10/3). 10/3 will give you a red conductor to use and can be handy for switched outlets or running two circuits in a single run. For example, a duplex outlet but each outlet of the pair is on a separate circuit (a 'black' 120 V and a 'red' 120 V side by side). It might be overkill but I overengineer just about everything. Certainly 10/2 is probably good enough.

[Mike Hollingsworth]

A 250' roll of 10 is cheaper than 100 ft rolls of 10 and 12.

[Lud martinson]

Steve, I agree with the 10/2 guys installed externally from a panel on your shop wall as well. The issue is when several machines kick on simultaneously and the startup draw may exceed your protected circuit.

[Jim Becker]

10/2 w/ground is fine but you might consider 10/3 w/ground (the w/ground is implied, BTW...so just 10/2 or 10/3). 10/3 will give you a red conductor to use and can be handy for switched outlets or running two circuits in a single run. For example, a duplex outlet but each outlet of the pair is on a separate circuit (a 'black' 120 V and a 'red' 120 V side by side). It might be overkill but I overengineer just about everything. Certainly 10/2 is probably good enough.

True, that 10/3 adds flexibility, but for pure machine circuits, it raises cost, especially at today's prices due to the cost of copper combined with the fact that it's unlikely you'll use that extra conductor.

[Mike Henderson]

True, that 10/3 adds flexibility, but for pure machine circuits, it raises cost, especially at today's prices due to the cost of copper combined with the fact that it's unlikely you'll use that extra conductor.
I agree. I haven't priced it in a while but when I did, 10/3 was a lot more expensive than 10/2. Probably because they don't sell as much of it.

Mike

[Jim Becker]

I agree. I haven't priced it in a while but when I did, 10/3 was a lot more expensive than 10/2. Probably because they don't sell as much of it.

Mike
Sales volume might contribute a little, at least in some outlets, but 10 gage wire has a lot of copper in that extra conductor and that most certainly is a significant cost factor.

[Steve Peterson]

I have a 5hp cyclone DC and a 5hp air compressor. Some people use table saws with big motors. I also use several welders and a plasma cutter that each take a 50 amp circuit. I don't know of anything else in a shop that would need wire for over 20 amps.

For all my 20 amp 220 circuits I ran 10-2/g in case I needed it later. The difference in cost of materials was not significant.

JKJ

My 5hp tablesaw and 5hp DC both recommend 30A lines which would require 10ga wire. Everything else in my shop is 20A or less.

Steve

[Chris Padilla]

True, that 10/3 adds flexibility, but for pure machine circuits, it raises cost, especially at today's prices due to the cost of copper combined with the fact that it's unlikely you'll use that extra conductor.

I haven't priced 10/2 vs 10/3 lately so I can't comment there. Certainly, it will cost more. It does provide the flexibility to multi-wire a box with two separate circuits thus returning on one neutral so I would think in that situation, it would be cheaper to run 10/3 instead of two 10/2 wires.

[Van Huskey]

Copper prices have actually tanked. The price of copper is at a 7 year low and 50% of what it was 5 years ago. 1000 ft of 12/2 is about $160 RETAIL. The 3 conductor NM wire tends to run 40% more than 2 conductor (sometimes even double in some shorter length rolls). It almost certainly is a result of lower demand.

While proces certainly vary by region prices here are about $95 for 250ft of 10/2, 10/3 is about $140

[Jim Becker]

VH, I hadn't looked at wire pricing in awhile but had to pick up a little today for a bathroom renovation I'm doing. You're correct, the prices have moderated since the last time I bought.

[Mike Henderson]

I haven't priced 10/2 vs 10/3 lately so I can't comment there. Certainly, it will cost more. It does provide the flexibility to multi-wire a box with two separate circuits thus returning on one neutral so I would think in that situation, it would be cheaper to run 10/3 instead of two 10/2 wires.
Just for clarification, Chris: Are you proposing that you would use 10/3 to provide multi-drop 120V circuits but be able to use the two "outside" wires to get 240V? Simultaneously?

Mike

[Jim Becker]

Just for clarification, Chris: Are you proposing that you would use 10/3 to provide multi-drop 120V circuits but be able to use the two "outside" wires to get 240V? Simultaneously?

Mike
I sure wouldn't do that...but that's me.

[Van Huskey]

Just for clarification, Chris: Are you proposing that you would use 10/3 to provide multi-drop 120V circuits but be able to use the two "outside" wires to get 240V? Simultaneously?

Mike


In a quick look I couldn't find NEC code saying you can't, but I bet most inspectors would lose their minds (and it probably does violate code). First problem would be you would have to have the 120v outlets match the breaker so if you were using a 30 amp breaker on the 10/3 you would have to use a 30 amp 120v receptacle which is about as useful as teets on a boar. If you use a 20 amp breaker you could have wired with 12/3. In the end the best practice would be to put in a sub-panel and run seperate circuits for the 120v and 240v if you already have the wire run in a closed wall.

[lee cox]

I have an old shop detached from my house where I sure wished the PO would have wired it with heavier wire. I would now need to pull all the wood walls, shelves and cabinets down to try and fix it.

[Dan Friedrichs]

I think Chris is talking about a multi-wire branch circuit. You can use a single piece of x/3 wire to get two 120V circuits. They "share" the neutral, but they're on different phases, so the neutral current cancels, and you still get away with using a single piece of the same gauge wire.

It saves one conductor compared to running two separate x/2 cables.

[Mike Henderson]

I think Chris is talking about a multi-wire branch circuit. You can use a single piece of x/3 wire to get two 120V circuits. They "share" the neutral, but they're on different phases, so the neutral current cancels, and you still get away with using a single piece of the same gauge wire.

It saves one conductor compared to running two separate x/2 cables.
Yep, Dan. I understood that much. But why use 10/3 in that situation (instead of 12/3)? And would that help you in a conversion to one or more 30 amp 240V circuit(s)? Seems that as soon as you went 240 you'd have to disable all the 120.

I'm sure Chris has something in mind but I just didn't understand it. He knows electricity pretty well.

Mike

[Van Huskey]

Yep, Dan. I understood that much. But why use 10/3 in that situation (instead of 12/3)? And would that help you in a conversion to one or more 30 amp 240V circuit(s)? Seems that as soon as you went 240 you'd have to disable all the 120.

I'm sure Chris has something in mind but I just didn't understand it. He knows electricity pretty well.

Mike

I agree that it wouldn't be a standard 120v MWBC like you see so commonly in kitchens since by code they are required to have two 120v circuits. The 10 gauge wire is what has me baffled. You can't attach them to a standard 15 (or even 20 amp) receptacle and the need for 30 amp 120v receptacles is pretty much nil, you could pig tail it in the box down to 12 gauge (to fit the 15/20 amp receptacle) but you would have to have it on a 20 amp breaker so why the 10 ga. It does give you lots of options once you have it in the wall but you can not run 30 amp 240v and 20 amp 120 without a breaker prior to any 12g/14g wire or 15/20 amp receptacle.





I have a similar setup on my boat dock. I have 10/3 running from the house on a 20 amp breaker, 10 gauge due to the length of run, but it is split in a sub panel with 240v going to the boat lift and 120v off one leg going to the receptacle for the charger for the boat batteries and the other leg running a lighting circuit.


That reminds me to give a shoutout to Leeson motors, they provided the manufacturer of my boat lift with the washdown motors and even after a week submerged in the recent Louisiana floods all five of us in the neighborhood with the same lift had ZERO issues with the motors, everyone else who had Asian motors (supposedly washdown as well) has had to replace their motors. This isn't to say the Asian motors didn't meet their spec, a washdown motor is not designed to be submerged but these American made Leesons all passed the week long submersion test.


Edit: rereading Chris' post I think maybe he simply meant you could run a simple 120v MWBC (I didn't think that the first time), on the second read I don;t see anything about a 240v at the same time. I think the point was flexibility later with wire in the wall. You would just have to use a 20 amp breaker and pigtail the wires in the box down to 12g to fit the receptacle terminals.

[Dan Friedrichs]

If you were doing 20A 120V circuits, yeah, you'd just use the 12/3, unless you wanted the future-proof-ness for 30A circuit(s) (either 2 120v circuits or 1 240V circuit).

I've always wondered if there is a reason you can't run a 120V circuit and a 240V circuit off a single piece of x/3 wire, though. Have the hots go to your 240V receptacle, and one hot and the neutral go to your 120V receptacle. Same situation as exists in an electric clothes dryer, just with two separate receptacles instead of a single 4-wire receptacle. Seems like there is no danger to doing it. The "wire utilization" would be better than two separate x/2 cable runs (if you only used one circuit at a time). Maybe it's just inconvenient because you're sharing the capacity of one wire between two circuits. Still, for situations like a shop where there may be mix of 240 and 120 tools, and if only one tool gets used at a time, it seems advantageous.

[Mike Henderson]

If you were doing 20A 120V circuits, yeah, you'd just use the 12/3, unless you wanted the future-proof-ness for 30A circuit(s) (either 2 120v circuits or 1 240V circuit).

I've always wondered if there is a reason you can't run a 120V circuit and a 240V circuit off a single piece of x/3 wire, though. Have the hots go to your 240V receptacle, and one hot and the neutral go to your 120V receptacle. Same situation as exists in an electric clothes dryer, just with two separate receptacles instead of a single 4-wire receptacle. Seems like there is no danger to doing it. The "wire utilization" would be better than two separate x/2 cable runs (if you only used one circuit at a time). Maybe it's just inconvenient because you're sharing the capacity of one wire between two circuits. Still, for situations like a shop where there may be mix of 240 and 120 tools, and if only one tool gets used at a time, it seems advantageous.

I don't know if that would fly for code, but if we ignore code, you could put a 30 amp breaker in the box because that would match the 10/3. And then do as you describe and provide both 120 and 240 on the same wires, with a limit of 30 amps on any "outside" wire.

Mike

[Van - is your place in the Denham Springs area of Louisiana?]

[Art Mann]

I don't believe that using 3 conductors plus ground to supply both 120VAC and 240VAC on one circuit is prohibited by the NEC. While I haven't done it, a few people on this forum described how they had both 120 and 240 outlets in one box. Of course, if the breaker were 30A, then the 120VAC outlet would have to be rated at 30A as well. That would be pretty unusual.

[Van Huskey]

I don't believe that using 3 conductors plus ground to supply both 120VAC and 240VAC on one circuit is prohibited by the NEC. While I haven't done it, a few people on this forum described how they had both 120 and 240 outlets in one box. Of course, if the breaker were 30A, then the 120VAC outlet would have to be rated at 30A as well. That would be pretty unusual.

I agree as I didn't find anything glaring in the NEC that would prevent it, while it might present an unbalanced load on the circuit this happens all over household wiring and if the load exceeds the breaker capacity on one leg the double pole breaker will trip both legs, by design. I don't think there is an issue here as long as someone is not trying to cheat a neutral with a ground using X/2 NM which is against code. Now, I would NOT be surprised to see an inspector ding this arrangement since it is not common practice and a AHJ might have a specific or vague rule against it.

Mike, I am 30 or so miles south southeast of Denham Springs. The problem was code (many houses in rural areas predated codes) required the standard 1 ft above the 100 year flood stage and the water was 3 feet above the 100 year flood here and higher in some areas. The VAST majority of the homes were in the preferred flood zone so mortgage companies didn't require flood insurance and the areas had never flooded in recorded history. People in waterfront neighborhoods like mine who are used to minor flooding every couple of years see things differently, kinda like the people who build on cliffs overlooking the ocean in CA, we know if we live here long enough there will be a major flood, most of use are built 5-6 feet above code. I honestly hate to leave the neighborhood as 70% or so of homes in our parish had damage, there are huge piles of drywall/flooring/insulation/furniture/appliances and just peoples lives in general sitting on the sides of the road in front of almost every house, fortunately they got the main road cleaned up last week and they were hauling off the debris from the road outside my neighborhood yesterday and today. All I have to say is one 1,000 year rain event in my life is more than enough.

[Mike Henderson]

Mike, I am 30 or so miles south southeast of Denham Springs. The problem was code (many houses in rural areas predated codes) required the standard 1 ft above the 100 year flood stage and the water was 3 feet above the 100 year flood here and higher in some areas. The VAST majority of the homes were in the preferred flood zone so mortgage companies didn't require flood insurance and the areas had never flooded in recorded history. People in waterfront neighborhoods like mine who are used to minor flooding every couple of years see things differently, kinda like the people who build on cliffs overlooking the ocean in CA, we know if we live here long enough there will be a major flood, most of use are built 5-6 feet above code. I honestly hate to leave the neighborhood as 70% or so of homes in our parish had damage, there are huge piles of drywall/flooring/insulation/furniture/appliances and just peoples lives in general sitting on the sides of the road in front of almost every house, fortunately they got the main road cleaned up last week and they were hauling off the debris from the road outside my neighborhood yesterday and today. All I have to say is one 1,000 year rain event in my life is more than enough.
I'm assuming you live on the Amite River. I'm from south Louisiana and graduated from LSU. I have friends in Denham Springs and have communicated (and continue to communicate) with them about the flood and the after effects.

Mike

[Van Huskey]

I'm assuming you live on the Amite River. I'm from south Louisiana and graduated from LSU. I have friends in Denham Springs and have communicated (and continue to communicate) with them about the flood and the after effects.

Mike

Close, I live on the Amite Diversion Canal, it may have been completly unpopulated when you were here. 15-20 years ago there were almost no homes and just a few camps, today it is neighborhood after neighborhood covering the entire diversion until you get to areas where there are no roads, there is even a community you have to drive a golf cart into since the roads stop 1/2 mile or so from the houses, not to mention the houses only accessible via boat. Mike, I have been away so long I forgot you were from this area, but when I read it I immediately remembered you had gumbo and jambalaya "tutorials" on your website! As you know it is a mess down here, but all our family (actually my in-laws, I am not from here) and close friends were not impacted directly. My entire neighborhood was stuck in our homes for 5 days though during the crest. The only trouble for me was having to ride my dog in my kayak 1/2 mile twice a day to the closest ground. We did have three boats sink due to being tied to tight to their lifts, I tried to swim out to retie one of my neghbors but even with full scuba fins the current caught me half way into my front yard and I was 100 yards downstream before I could get back the 50 feet or so to where I could climb onto a front porch, we times floating debris over known distances based on lot size and estimated the current in the middle of the river was running ~42 mph, USCG boats could barely run 10mph upstream. As with many disasters of this type the ones least finacially capable of dealing with the issues are the ones hardest hit.

BTW sorry about LSU today that was the definition of heartbreaker, while I have no skin in it my brain will be saturated with the omnipresent "fire Les Miles" chants at least until next Saturday. Hopefully the Saints will win tomorrow or I'll be ready to jump off the Mississippi bridge after a couple of days.