2 or 3 Wire for Shop 220v?

[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.