Pigtailing 220v outlets in new shop

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  #1  
Old 11-23-14, 10:22 AM
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Pigtailing 220v outlets in new shop

I'm currently wiring up my first shop, about 280sqft, and successfully completed all my 110v outlets. But now I've realized an error with my 220v outlets.

I had planned to have one 220v outlet on it's own circuit for dust collection, and a string of other 220v ('more than I need, but just in case' was my thought process) on the same circuit seeing as I would never, ever, ever be using them at the same time.

So I have gotten to the point where I have pulled all my wire through into each outlet box and prepped it for wiring the outlets, and now I see that 220v outlets only have 2 connectors in and none out. D'oh. I'm from England and we run 240v outlets off of each other - I think - so I didn't consider it til I got to the subpanel and realized I only have one hot wire for my double pole breaker - I'm using 10/2 wire. I know I know.. totally wrong. I've had help from an ex-electrician and thought I'd be clear with my questions regarding what to use. I suppose I asked the wrong question and hence got the wrong answer.

So, here's my options:
1. Tear out the most of my wire, and run a new circuit for each outlet off of it's own breaker using 10/3 wire. This is the correct way to do it.
2. Same as above, using 10/2 wire using the neutral as a hot. Slightly less correct.
3. Pigtail all my 200v outlets using the current 10/2 wire using neutral as hot. Make it perfectly clear on all my outlets that I can only ever run one machine off of that circuit at the same time. These outlets are purely for futureproofing - I may end up with table saw/planer etc one day that doesn't use 110v.

I know no one should suggest to me that I do something even remotely under code, but this is not going to be inspected. I want to go with option 3.

Am I going to burn my shop down?
 
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  #2  
Old 11-23-14, 10:37 AM
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A true 240vac appliance does not need a neutral. For most 240vac machines you only need to run two wire cable with ground so what you've run is fine.

Also nothing wrong with using 10-2 instead of 12-2. Plenty of current carrying capacity.

You must dedicate the 240v circuit to 240v use. You can't use 120v appliances off the 240v circuit. You need to run the 120v receptacles off their own circuit.
 
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Old 11-23-14, 10:37 AM
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Are you IN England, or FROM England, living in the US?? In the US, it is nominally 120 volt and 240 volt system. Where is your main panel located? Do you have a subpanel located in the shop, or is your wiring directly from the main panel in the house? Is it attached or detached from the house? Sorry for the questions, but we just gotta know.
 
  #4  
Old 11-23-14, 12:39 PM
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From England, living in TN, new to all of this!

I'm having 2-2-4 AL run 60ft from a 100A breaker in the house to a 100A subpanel. From that panel I have four 120V circuits (on 12/2) on 20A breakers and - this is where the debate is now - two 240V circuits (on 10/2). One dedicated for dust collection, and the other for multiple (does it really matter how many?) outlets to be used for potential planers/jointers/table saw.

As I said before, I'd like to have them all pigtailed to save time, effort and money, seeing as only one will ever be used at the same time. Do you suggest using a junction box for this, or just an enlarged outlet box? I don't think the ones I'm using will fit all the 10/2 pigtailing that will be going on!

**EDIT**

With this configuration would I be able to leave my tools plugged in while not running? Or perhaps I could find outlets that have a built in on/off switch (for the outlet itself, not any lights).
 

Last edited by Mark Gunther; 11-23-14 at 12:59 PM.
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Old 11-23-14, 12:58 PM
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Yes.... you can put several 240v receptacles on one circuit. The circuit is protected by a circuit breaker that will trip if you try to run too many devices at once.
 
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Old 11-23-14, 01:48 PM
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You should be running a 4 wire feeder to the shop panel. Two hots, a neutral and a grounding conductor.
 
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Old 11-23-14, 02:14 PM
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I should, but that entails a whole host of additional costs that I don't want/really need to get into. People around here tend to redneck it and do it the old 3 wire way, that'll work as well right? Just not as ideal as it ought to be..
 
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Old 11-23-14, 02:39 PM
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I am sorry, but only code compliant advice will be given here. Sorry if that involves extra time or money.

The standards change to enhance life safety.
 
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Old 11-23-14, 07:10 PM
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I understand, but my electrician is saying 3 wire AL (2-2-4) is good enough, so it would help me a lot if you could tell me why that will not suffice for reasons other than the code.

I could do plenty of things outside of the code and be fine, so knowing whether this issue is one I can't afford to cut corners on is critical. My electrician has a clear conflict of interest in that he wants to get the wire you can pick up locally and git 'er done.

Please could you explain to me why I must use quadruplex and not triplex?
 
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Old 11-23-14, 07:16 PM
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When the code allowed three wire sub panel connections a hazard existed that no one was aware of. If you loose the combination ground and neutral wire..... you've lost your equipment ground. If there was an unbalance between the hot legs.... the difference would appear on the ground/neutral causing the ground to now become live and your two hot legs would no longer be 120v to neutral.

This three wire quandary also affects 120/240v appliances. If the neutral/ground were lost... the metal frame of the appliance would now become live.
 
  #11  
Old 11-24-14, 05:00 AM
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Does this affect the outlets I need to use?
 
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Old 11-24-14, 06:33 AM
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I'd suggest you get rid of the hack that wants to do it wrong and perhaps create a safety situation and do it yourself. You will undoubtedly, even with the cost of the correct wire, save money doing it yourself and we can help you do it correctly.
 
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Old 11-24-14, 07:10 AM
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My electrician has a clear conflict of interest in that he wants to get the wire you can pick up locally and git 'er done.
Hey, you are in Tennessee, not New York City, mobile home feeder is very common there. What do you have against doing it right?

Shop Encore Wire 2-2-2-4 Aluminum Mobile Home Feeder Service Entrance Cable at Lowes.com

Southwire 500 ft. 2-2-4-6 Aluminum USE MHF Service Entry Electrical Cable-30163001 at The Home Depot
 
  #14  
Old 11-24-14, 07:23 AM
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Thanks everyone. I called another electrician and feel good about his attitude. He told me he will use 2-2-2-4,so I'm all for it.

I understand that I need to use a GFCI outlet on the first outlet of my 120v circuits, do I have to do something similar with my 240v circuits?

I would do it all myself, but after checking out the wire situation under the box in the crawl space I'm reluctant to go anywhere near it. Wires everywhere, no empty holes for new feeder etc. I'm not going to go under there and blind fire with a drill, so I gotta go pro on this one.
 
  #15  
Old 11-24-14, 07:33 AM
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No, the feeder doesn't directly affect the outlets in the shop, however it does make them less safe to operate. I can't quantify how much less safe other than to say I've seen a lot of burned off service neutral/ground wires, so it's not a theoretical risk -- it actually happens pretty frequently.

Three-wire feeders were legal for many decades, and I bet still are legal in some parts of the country based on slow code adoption. It's possible it is still legal in your area, but I think we've done our due diligence in warning you it is not state of the art in terms of safety and may be illegal in your area.

The 10-2 cable may be used for 240V receptacles which do not have neutrals. Common examples of these receptacles used in woodshops are NEMA 6-15 or NEMA 6-20. In that case, the white wire is re-identified using red tape or ink to mark it as a hot wire. The white should be marked red at every box where it is present to avoid confusion. This leaves you with the two hots and a ground necessary for a 240V circuit. There is no limit in the code as to how many outlets you can have on the same circuit, but you do need to give consideration to how many tools run simultaneously on that circuit. It sounds like you only expect one tool plus the dust collector at any given time, so I see no problem with the plan for your receptacles.

GFCI protection is not required for 240V receptacles in a wood shop.
 
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