Single shutoff switch for a 220v Ciruit

Hello,
I am in the process of wiring my workshop and wanted to be able to have a single cutoff switch for the circuit so that I can cut the power to the circuit when I exit the workshop (for safety reasons).
Looking at the switches at Lowes and Home Depot, while they handle the 220v, but it appears that I would need two switches for each circuit. One for the black side, one for the red side.
Is there a wall switch that I can install that will cut the entire 220v circuit off with one switch? Or do I need to do similar to what a ciruit breaker does by combining two breakers (switches) together to shut off the circuit.
I am installing several circuits, so I want to limit the number of switches required to shut off the power in the workshop.
Any advice is greatly appreciated.
David
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Yes. Look for/aks for double-pole switch. They're less common so not usually stocked in the high volume places. It will open both hots simultaneously with one switch. IFF you're in the country I think you're in. 220 not necessarily = 220 the world over.
Pop

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David Lankford wrote:

You need a 2-pole switch. I think DPDT switches are used for 4-way light switches, but that might not be heavy enough duty for electric motors. Look for an air conditioner disconnect (available fused or unfused.) They are cheap and heavy duty.
I would use a small main-lug breaker panel. A 70A panel usually has 2 or 4 spaces, and 125A panels with 6 spaces are common (and cheap, but not as cheap as an A/C disconnect.)
Bob
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You're talking about two different things here, and you don't understand the difference -- which could lead the OP to create a hazard if he buys a 4-way switch, thinking it will do what he needs. It will NOT.
A 4-way switch is a special type of DPDT switch, which does NOT disconnect power -- it only changes the route. Consider the four terminals as labelled A, B, C, and D. With the switch in one position, A connects to B, and C connects to D. With the switch in the other position, A connects to D, and C connects to B -- manifestly NOT what the OP needs.
The OP needs a plain old DPDT switch, rated for 20A at 250V, which is easily found at Lowe's or Home Depot.
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(Doug Miller) wrote:

Oops, typing too fast -- he needs a DPST switch, not a DPDT.
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Doug Miller wrote:

A DPDT will work if he can't find a DPST. He'll leave one set of terminals open. (BTW, I thought a 4-way light switch had all 6 terminals, not just 4.)
I would still use an A/C disconnect if there's just one 240V circuit to switch. I know it can handle an inductive load.
Bob
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Depends on what type of DPDT switch he uses. If he "leaves one set of terminals open" on a 4-way switch, it will always be off. I repeat: a 4-way switch is NOT what's needed in this application.

Nope, four terminals. Conventional DPDT switches have six.
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Well, a DPDT switch will work just as well, you just don't connect the bottom screws.
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you're a bit unsure of what you're doing (as the OP seems to be) they're also confusing to wire up.
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Yep -- it's called a DPST switch (double pole single throw). Disconnects both sides at once. And they sell them at Lowe's.
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The amperage you are dealing with will determine the switch you need. An air conditioner disconnect comes to mind. Also if you are dealing with several circuts you are creating a bigger problem. The easiest solution may be to put in a second breaker panel that you run just the 240 volt circuits out of. Run the lights and outlets out of the "first" panel. Then you can shut off the main breaker in the second panel to kill all the circuits at once. Greg
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All,
Thanks for the advice.
I went back to Lowes this evening and here is what I found.
1. 20amp Double Pole Switch (Will handle up to 12 gauge wire) 2. 30amp Double Pole Switch (Will handle 10 gauge wire) 3. A/C Disconnect
While the 20amp DPST switch will probably meet the need, the quality of the 30amp DPST was much better and it does give me some flexibility in what I can connect/disconnect.
It appeared to me that the A/C disconnect is a bit of overkill for my particular situation, but I am curious as to ZXCVBOB's comment, "I would still use an A/C disconnect if there's just one 240V circuit to switch. I know it can handle an inductive load." What issues might I run into using a 30amp DPST switch that a A/C disconnect would be a better choice for?
I had originally planned to wire the shop with 12-3 for all the 220V circuits, but now seeing the 30amp swithes and given that I might go to something with a higher amp rating, I am now inclined to run 10-3 and use the 30amp switches to disconnect.
There always is the option of just going to the breaker box to kill the circuits, but I know that I will not think and skip going to the breaker box when I get called away from the shop. If the switches are right above the light switch, I will form a habit of killing all the power when I leave the workshop. My father had his shop setup this way and it was easy to close up, one swipe of the hand killed the outlets and lights.
BTW, as a part of this project, I have added another 200amp panel to run all of these circuits from. Additionally of note, to give myself flexibility to rearrange the shop in the future, I am running more circuits / outlets than I need, but to me the expense now is minimal compared to re-wiring once the space has been finished.
Thanks for everyone's input so far.
David

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David Lankford wrote:

An inductive load will burn up the contacts on a switch fairly quickly if you turn the switch on and off (especially off) under a load. I can't see your 30A switch from here, and I don't know if you are planning to only flip the switch when all the machinery is off or not.
Are you wiring a 30A 240V branch circuit? What outlets are are you using, or is the machinery hardwired? (it's safer with a cord-and-plug so you can yank the plug in an emergency to disconnect it.) Or do you have a fused switch at each machine to provide overcurrent protection and emergeny shutoff?
Unless you have individual fused switches at each machine, I think a small load center would be better for what I think you're doing. Put the lights on the first switch, and a couple of 240V circuits and at least one 120V circuits in the rest of the spaces. When you leave, turn off all the breakers except #1.
Like I said, I can't see what you're doing from here and I'm making a lot of assumptions.
Best regards, Bob
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The purpose of these switches is to put a power disconnect (set of switches) up out of the way so that I don't have to worry about power going to tools when I am not around. Honestly, it's not that inconvenient going to the 200amp panel to cut them off, but this was one of the ways that I learned to respect tools and the power that feeds them and IMO, it's a quick and convenient (I will do it) way to make sure the power is off to all machinery prior to leaving the shop. Having a 9 year old son who is interested in working on things, while he understands and respects the power tools, I feel it's a small price to pay for an added level of security.
Each circuit will have two 20amp 250v single plug outlets. Depending on the requirements of the new tablesaw, I might have to use a different outlet for that plug. The largest motor will be between 3hp and 5hp (tablesaw), but most are in the 1hp to 2hp range.
Additionally, all machinery will be on cord/plug into outlets that can be pulled in an emergency.
David

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If you are runnign motors off these switched you might want to look into motor rated switches. they look like reg swtiches but are rated for different horsepowers and different voltages. here is a link http://www.leviton.com/pdfs/switches/PowerSwitch_booklet.pdf
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