2 or 3 Wire for Shop 220v?

[Steve Mathews]

Is there any need to run 3 wires (plus ground) for my shop 200v outlets or is 2 wires sufficient? Another way of putting it, is there any machine or potential use that may require 3 wires?

[Jim Dwight]

220V is line to line. Line to ground is 110V. So unless the 220V appliance also has a 110 circuit (i.e. stoves, dryers) you only need the two line wires (and a ground). That is at least true where I live. I paid an electrician to run wires for a recent addition but did the finish myself. I didn't know when I agreed to do it that meant hooking up the two 220V circuits to the heat pump but I managed. Both were just two insulated wires and a ground. Air handler was 8 gauge and condenser was 10 gauge (it's a 2 ton unit). No manual or other instructions were available but the devices had little diagrams on them.

[Wade Lippman]

I had a table saw that needed 120/240 because the starter had a 120 relay. I replaced the relay.
Other than that I have never seen a shop tool that required both.

[Mike Gresham]

The shop in the house I recently bought was already wired 3 wire plus a ground. I decided that was fine by me because, if I ever needed it that way, I didn't have to rip stuff up to change it later.

[Art Mann]

I have one 30A outlet that is configured for both neutral and ground - just in case. The rest just include both hot legs and ground. The only 240VAC shop equipment I have seen that required a neutral connection was a 5 hp drum sander that had a small 120VAC motor just for the variable feed mechanism.

[roger wiegand]

I've found it very convenient and worth the small cost of the extra wire to use a 3 wire "multi wire branch circuit" for all of my non-dedicated circuits (I know others here disagree, fairly vehemently). At most locations I put in a quad 120 V outlet, with each pair on a different circuit and one or two 240 V outlets. Many of my tools have accessories (e.g. a lamp) that wants 120 V, while almost all the tools are 240 V. For dedicated large draw tools (e.g. dust collector, compressor, table saw) they get a 2 wire 240 V circuit. It's easy to reconfigure this setup as needs change.

I've never run across a power tool wired to require both 120 and 240, tools that need it that I've seen, like my sander, have two plugs, one 240 V for the sander motor, a second 120V for the feeder.

[Julie Moriarty]

Is there any need to run 3 wires (plus ground) for my shop 200v outlets or is 2 wires sufficient? Another way of putting it, is there any machine or potential use that may require 3 wires?

Yes.

If you are wiring for specific machinery, you need to have the manufacturers specs on wiring requirements and outlet (NEMA) configuration. If you're wiring for whatever you may need, pull a neutral in with each 240V pair. (The majority of homes run on 120-240v. 110-220 is obsolete.) If you're running pre-wired cabling (Romex, BX, etc.) use 4-wire cabling. The difficult question to answer is what gauge wire to pull? At a minimum, in a workshop, you should be running #12 (gauge) wire. But you may need #10 (typically 30 amp loads) or larger, depending on the load. So it's always good to configure your anticipated machinery and load demands before wiring your shop, and plan for the future when doing so.

[Buck Williams]

220V is line to line. Line to ground is 110V. So unless the 220V appliance also has a 110 circuit (i.e. stoves, dryers) you only need the two line wires (and a ground). That is at least true where I live. I paid an electrician to run wires for a recent addition but did the finish myself. I didn't know when I agreed to do it that meant hooking up the two 220V circuits to the heat pump but I managed. Both were just two insulated wires and a ground. Air handler was 8 gauge and condenser was 10 gauge (it's a 2 ton unit). No manual or other instructions were available but the devices had little diagrams on them.

It's line to neutral, not line to ground which gives you 110 or 120V.

[Julie Moriarty]

It's line to neutral, not line to ground which gives you 110 or 120V.

It's either. Anytime you want to check the voltage of a current carrying conductor, you should first check it to ground. If you can't find a ground close enough, you then check it to a neutral you know is good. When a transformer is tapped to split 240v into 120v, the center tap becomes the neutral and either hot leg to neutral will read 120v. Often, the neutral is bonded at the service entrance creating direct continuity between ground and neutral. But even if the neutral is isolated, you will still get a full voltage reading from any hot leg to ground or neutral.

[Buck Williams]

I stand corrected, didn't read Jim Dwight's post thoroughly, one leg to ground will read 120V on a meter, if you need 120V for a timer or a lamp etc.. in addition to the 240V for the motor or appliance, which Jim stated, you do need to go use one leg and a neutral. Sorry, I just wanted to make sure that someone didn't think that it was OK to use a hot leg and the ground to pick up an auxiliary 120V.

[Phillip Gregory]

Your main panel in the shop will almost certainly have two hots and a neutral feeding it, so you can run both 120 V and 240 V equipment in the building. I believe it is code as well to have to run a neutral to the panel as well with standard 240 V single (split) phase. Nearly all 240 V shop equipment is 240 V only and you will just need to run two hots and a ground to them. For typical shop equipment a 3 hp motor will need a 12/2 wire with a 20 A breaker and a 5 hp motor will need a 10/2 wire with a 30 A breaker. You do have to tag the white wire at both ends with a piece of electrical tape or mark it with a marker to indicate it is actually a hot rather than a neutral.

Anything over 20 amps has to be on a dedicated circuit but in most places you can have more than one 20 amp/240 V receptacle on a branch. You just need to be careful there as you may exceed 20 amps by having two tools running on the same circuit at the same time.

[Phillip Gregory]

It's either. Anytime you want to check the voltage of a current carrying conductor, you should first check it to ground. If you can't find a ground close enough, you then check it to a neutral you know is good. When a transformer is tapped to split 240v into 120v, the center tap becomes the neutral and either hot leg to neutral will read 120v. Often, the neutral is bonded at the service entrance creating direct continuity between ground and neutral. But even if the neutral is isolated, you will still get a full voltage reading from any hot leg to ground or neutral.

Per the NEC the ground is bonded to the neutral at the service entrance only. Your neutral should not be bonded to the ground if your shop's panel is a subpanel but it must be if your shop's panel comes straight off the meter and is a separate service entrance. You may not get a correct hot to neutral reading if there is some gross imbalance between the two 120 V legs occurring somewhere causing a significant neutral current. That would be a separate problem in itself though...

[Julie Moriarty]

There are situations where the neutral is bonded past the service entrance. I've never seen it in residential applications but I have seen it in commercial and industrial applications. The NEC is the starting point for how things should be put together but doesn't cover every situation and is sometimes behind the times. But if one is concerned about passing inspection, one will always get the right answer to every installation question if you ask your local inspector. And don't be surprised if his or her answer is different than the NEC.

Buck, you are right about not using a ground to complete a load circuit. I was talking only about checking voltage with a meter and hope I wasn't giving the impression a ground is an acceptable neutral. As for funky neutrals, they certainly exist and they can be a nightmare to trace out. That's why I stated "check it to a neutral you know is good." Anyone checking voltage should never assume the neutral is good for doing that. That's why we (electricians) always start with a ground when getting a voltage reading with a meter. Of course, you have to know the ground is good too. Same goes for whatever meter you are using. Check, check and double check everything. It's a process drilled into our heads from day one. And sometimes the failure to verify everything is as you assume it to be drills it in even further.

[Phillip Gregory]

There are situations where the neutral is bonded past the service entrance. I've never seen it in residential applications but I have seen it in commercial and industrial applications. The NEC is the starting point for how things should be put together but doesn't cover every situation and is sometimes behind the times. But if one is concerned about passing inspection, one will always get the right answer to every installation question if you ask your local inspector. And don't be surprised if his or her answer is different than the NEC.

The Authority Having Jurisdiction can certainly (and often does) make up their own rules. What they say is what you have to do, or you fail the inspection. Many places out in the sticks like where I live don't have any permitting or inspections so the NEC is the default for what you do.

[John Lifer]

Is there any need to run 3 wires (plus ground) for my shop 200v outlets or is 2 wires sufficient? Another way of putting it, is there any machine or potential use that may require 3 wires?

No woodworking machine that you will use. Appliances, such as range and most dryers now require 4 wire 240 circuits. But If it were me, (and I ran my last shop this way) is to run 3 wire.

[Phillip Gregory]

^ I think that John is counting the ground wire in his number or wires. Convention is to only count the insulated conductors. The ground in nonmetallic cable you'd run in your walls is bare wire so it doesn't count. An extension cord on the other hand DOES count the ground as it is insulated. You're not going to find a four-wire nonmetallic cable for normal residential use as it would have three hots, a neutral, and a ground- and be for carrying all three phases and the neutral for a three-phase wye setup.

[Ole Anderson]

I recently ran into the need for some isolated ground MC cable which had a hot, a neutral and two grounds, one green the other green with a yellow stripe. One went to the ground pin, the other to the metal box and the frame of the orange receptacle, as the frame was not bonded (therefore isolated) to the main equipment ground.

[Darrin Vanden Bosch]

Check with your local inspector

[Steve Mathews]

No woodworking machine that you will use. Appliances, such as range and most dryers now require 4 wire 240 circuits. But If it were me, (and I ran my last shop this way) is to run 3 wire.

Just curious as to your reasoning for running 3 wires?

[Steve Mathews]

Your main panel in the shop will almost certainly have two hots and a neutral feeding it, so you can run both 120 V and 240 V equipment in the building. I believe it is code as well to have to run a neutral to the panel as well with standard 240 V single (split) phase. Nearly all 240 V shop equipment is 240 V only and you will just need to run two hots and a ground to them. For typical shop equipment a 3 hp motor will need a 12/2 wire with a 20 A breaker and a 5 hp motor will need a 10/2 wire with a 30 A breaker. You do have to tag the white wire at both ends with a piece of electrical tape or mark it with a marker to indicate it is actually a hot rather than a neutral.

Anything over 20 amps has to be on a dedicated circuit but in most places you can have more than one 20 amp/240 V receptacle on a branch. You just need to be careful there as you may exceed 20 amps by having two tools running on the same circuit at the same time.

Thanks for this reply. This suggests to me that what might be correct for my application is to run 12/2 with a 20 A breaker to various locations or intervals in the shop for the table saw and other potential 240V equipment less than 3 hp. Since my only other current 240V piece of equipment is a planer I should be running a separate 10/2 with a 30 A breaker. Sound reasonable?

[Phillip Gregory]

Thanks for this reply. This suggests to me that what might be correct for my application is to run 12/2 with a 20 A breaker to various locations or intervals in the shop for the table saw and other potential 240V equipment less than 3 hp. Since my only other current 240V piece of equipment is a planer I should be running a separate 10/2 with a 30 A breaker. Sound reasonable?

I would have at least three circuits if I were you. I would have a dedicated circuit for your dust collector if you have one, since it will run at the same time as another tool and you may not have enough amperage left to run the tool connected to it. I'd then have a 12/2 wire feeding 20 A receptacles for the 2-3 hp tools, and a 10/2 wire feeding a single 30 A receptacle since it sounds like your planer is a 5 hp unit needing a 30 A circuit.

[Jeff Fischer]

My wiring is behind drywall so I ran a few 240v outlets in my shop with 10/4 wire, just because it adds flexibility for the future. It would not be as much of an issue with conduit.
You can choose to ignore the extra wire for now, if not needed, or if you change the configuration of the outlet to 120v later, or if you need to hookup a piece of equipment that takes an equipment ground, you will need the ground wire that's already there. Where I ran the wires to compressor and hvac disconnects I just used 3 wires, as these will not likely change.

[Bill George]

Yes.

If you are wiring for specific machinery, you need to have the manufacturers specs on wiring requirements and outlet (NEMA) configuration. If you're wiring for whatever you may need, pull a neutral in with each 240V pair. (The majority of homes run on 120-240v. 110-220 is obsolete.) If you're running pre-wired cabling (Romex, BX, etc.) use 4-wire cabling. The difficult question to answer is what gauge wire to pull? At a minimum, in a workshop, you should be running #12 (gauge) wire. But you may need #10 (typically 30 amp loads) or larger, depending on the load. So it's always good to configure your anticipated machinery and load demands before wiring your shop, and plan for the future when doing so.

Julie are you an electrician? Nice to have someone else on here that knows the NEC.

[Julie Moriarty]

Julie are you an electrician? Nice to have someone else on here that knows the NEC.
Yes, Bill. 35 years with the IBEW. Retired now. But don't mistake me for an NEC guru. Most of the comments I make here about electrical installations come from personal experience and what I learned from fellow electricians. Of course, all that was while working under local electrical codes, many of which begin with the NEC. While the NEC is a great guideline, it isn't perfect, IMHO. Nothing can replace experience in the field. And many municipalities don't adhere strictly to the NEC. My mantra is, "When in doubt, call your local inspector." As a master electrician yourself, I'm sure I'm not telling you anything new.

[Roy Turbett]

I ran 10/3 wire for my 220 circuits. Having a neutral available allowed me to add two 110 outlets to my Powermatic 90 wood lathe to run lights and a hand sander. The 3 phase motor and VFD use 220.

[Rick Christopherson]

Julie are you an electrician? Nice to have someone else on here that knows the NEC.No she is not an electrician. Being a member of the IBEW is a union position, not a licensed electrician. She was a designer and supervisor, not an electrician. You can look it up in her LinkedIn profile.

[Mike Heidrick]

I sure appreciate Rick and Julie's advice on many things electric though and a bunch more of you guys as well. I also love hearing examples of what people have done and what they are thinking of doing. Thanks for all the input on threads like these. I know it takes a lot of time to do it. To the code familiar I recognize the many years invested to become familiar with code and practice and the real world experience many of you have. Thank you very much.

To the topic, when wiring my latest shop I plan to just use 10/2 lines for 30amp circuits for my 220V 1ph tools. Almost all my large tools are 5hp now. I will run my 3hp tools on those too. I will have a 12/2 lines for 120V 20amp circuits everywhere as well, If a light or whatever is needed I will just use one of those outlets. The price of 12/3 and 10/3 is a lot more than 10/2 or 12/2 locally here at Menards. Ill take care of business with sure volume of outlets. I plan to have at least one 120V outlet above each 220V outlet. Every other 120V outlet will be on a separate 20a circuit. Every other 220V circuit will also be on a seperate 30a circuit. DCs will be on a separate 30a circuit as wells.

[Julie Moriarty]

No she is not an electrician. Being a member of the IBEW is a union position, not a licensed electrician. She was a designer and supervisor, not an electrician. You can look it up in her LinkedIn profile.

You obviously know nothing about IBEW membership. And you couldn't be more wrong about your assumptions. I wish I was still working so I could take this to work. They always appreciate a good laugh.

Maybe someday you can buy me a beer and I'll tell you all about how to become an IBEW Inside Wireman (my classification) and all about my career as an electrician. (State of Illinois certified Master Electrician) You might actually apologize for repeatedly jumping to conclusions. Then you'll probably start asking me to teach you how to bend conduit.

[Art Mann]

No she is not an electrician. Being a member of the IBEW is a union position, not a licensed electrician. She was a designer and supervisor, not an electrician. You can look it up in her LinkedIn profile.

We know a lot about Julie's credentials. What are yours, Rick?

[Ole Anderson]

I could see that coming.

Hmm, maybe I will start a thread on LinkedIn. I still get requests to join and I don't see the point now that I am retired.

[Art Mann]

Be careful Ole. You will get a lot of junk mail from Linkedin if you sign up. The reason I belong is to get notifications of the change of status of old friends I worked with before I retired. I never respond to the head hunters.

[Julie Moriarty]

Hmm, maybe I will start a thread on LinkedIn. I still get requests to join and I don't see the point now that I am retired.

I retired because working in the field was becoming much harder every year. So when I did, I thought maybe I could put the CAD I did on the last couple of jobs to work so I signed onto LinkedIn to see if I could find some company that wanted my skills. I didn't land any jobs but I got a ton of emails, mostly about people I've never met. They are like Facebook, a crocodile that once they have a hold of you, they won't let go. Listen to Art.