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#1
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240V wiring help
I have a stupid question. What's the difference between 240V outlets and 120V outlets, apart from the voltage? I had the electrician wire my shop for 120V and 240V, but I have to run all the inside wiring to save money. So now I have the 120V all wired and I looked for 240V outlets at Lowe's and they don't seem to have any. I intend to buy a couple of shop tools like a bandsaw that are 240V, but wondered how the plug was and if there's anything special I should use for wiring. I have Romex 10/2 and thought that would work for 240V. Am I wrong? Any explaination would be much appreciated.
-Dave |
#2
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10/2 will work fine as long as it has a ground wire as well. 240v outlets are singles, so if you were looking for duplexes that may have been the problem. The plug hole pattern can vary, but is usually like a standard three-prong with one of the flat prongs turned 90 degrees from the other. This odd leg can also be L-shaped, so the outlet hole pattern will often have the left-hand hole shaped like a sideways T.
Also remember that 240 has no neutral; both legs are hot. Most 240v appliances will have a sticker on the cord that says something like "use on single-outlet circuit only." They mean that. Those wires can get hot, especially if you go smaller than 12/2. I'm running my hammer (2hp 240v) on 14/2 and have not noticed a problem so far, but I know an air conditioner will really heat up the wires. |
#3
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Here is a link to a web site I found that describes the process...
http://www.bhg.com/bhg/story.jhtml;j...t230006&page=2 You will need a special 240 wire that has a red, black and white wire. Each leg of the circuit carries 120 volts (red, black) the white wire is the neutral or return wire. In 120 wiring the white is the neutral (always) and the black carries 120 and the ground is...well the ground. You will need to get a special plug for 240 as well. You don't want to plug a 120 motor into a 240 circuit. You can find different types of plugs to mate up to the type of plug. One of the 240 volt plugs are usually turned 90 degrees to keep them seperate. 120/240 plugs Hope this helps. And remember...electricity kills...so be extra careful. reid allen |
#4
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Reid Allen |
#5
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Good point! I meant that the wire which in 120 would be just an emergency ground is a needed neutral in 240. Thanks for clearing it up, we don't need any extra-crispy bladesmiths! |
#6
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That's great info guys. I really apppreciate the expertise here. I prepared the walls yesterday and think I have a handle on it. However, I was wondering if I can use the bare ground wire as the neutral wire? The cable I have is 10/2 and it has two covered wires (black and white) and one bare ground wire. I bought the 100ft of Romex cable for $3, so I really would like to use it. Also, the plugs look different at Lowe's like you said, but my vacuum dust system can be run at 120V or 240V and I wanted to re-wire it for 240V. Does that mean I have to strip the plug and put on a new one with the different prongs? You guys are a huge help. Thanks.
-Dave Last edited by David Peterson; 10-04-2006 at 09:28 AM. |
#7
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David,
Yes, you will need to change the plug, and re-wire the leads to the motor. Generally the wire connection to the motor is different if you run 240V or 120V. Most equipment that is rated to 240V also comes with a bare leads. There are a number of types of 240V plugs, and you are usually on the hook to wire whatever one you have in your shop up. I always use the 4-wire romex for 240V, but I am very anal about electricity. I always try and run 10 Ga also, just for the added safety. --Carl __________________ --Carl N-T Porkin' Pig Price ?? KN Auctions to help a member in need and score a GREAT deal! ?? |
#8
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Remember to buy all the same types of plugs and outlets. You may want to rearrange the shop in the future and your plugs won't work so you will have to move them as well.
I personally like the large black plugs that look like regular 3 prong plugs but one of the blades is smaller than the other. Everything I have that is 220 has that same plug, even if I have to cut off a perfectly good plug to change it to this type. Since you are not completely familiar with this process, please have someone check things out before you power it all up. |
#9
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I kinda figured I'd have to wire my own plugs, but I'm glad I got confirmatiion from you guys. Great idea about getting all the plugs the same. I'll definitely do that.
I'm still wondering though if I can use the 10 gauge wire (10/2) I have already with the two coated wires for the hots and the one bare wire for the neutral. Do I also need another wire for the ground? If so, could I run the 10/2 wire I already have and get another length of 10 gauge for the other wire (4th) and just put it through the same hole for the wiring? The more I save on wiring, the more tools I can buy to fill the shop. Thanks guys. -Dave |
#10
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David,
The 10-2 wire is what I used, it is fine. Just put the black and white into the breaker and the bare or green to the ground bus bar. I was told by my electrician that 10 gauge is fine for most shop equipment. If you are going to use a welder you will need a heavier wire. Such as mine I have a 50 amp mig welder and I have 6 gauge wires for this welder. Make sure you label your plugs, I have seen guys try to plug in 110 into 220 and vise versa they will even go to the point of twisting the blades with pliers so they can plug it in. |
#11
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The size of the wire (e.g. 10/2) has absolutely nothing to do with it's suitability for 240 volts. Wire siziing has to do with the ampacity of the wires. For example 10/2 is rated for 30 amp circuits, 12 guage wire is rated for use on 20 amp circuits, 14 is rated for 15 amp circuits.
The neutral wire is white or natural grey in color. The ground wire is bare (unisulated), or green. Ground is used to provide protection against electrical shock. Always ground your equipment, it may well save your life! If you need a neutral conductor for the operational requirements of a piece of equipment you need to run a four conductor wire and plug. Two hot leads, one neutral and one ground. This is what you will find on a range plug for your electric range at home. -Mike- |
#12
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The Range in my house has a 3 prong plug!
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#13
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I'm only running 20AMP equipment, so I should be fine on the wire gauge. I wanted to run 30 AMP wire, in case I wanted to upgrade to larger equipment later on. I will probably run the 4th wire seperate and still use the wire I have. No sense wasting good wire. It will be harder to run another wire, but cheaper in the long run.
-Dave |
#14
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All of the equipment I have currently is 3 wire, but I always run the 4 wire, so the outlets can handle anything. Imagine getting that new piece of equipment and finding out it is 4-wire and having to pull a new outlet before you can play
--Carl __________________ --Carl N-T Porkin' Pig Price ?? KN Auctions to help a member in need and score a GREAT deal! ?? |
#15
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Quote:
Whoops.... should have been a little more accurate...........all newer ranges are 4 prong. It's an NEC (national electric code) requirement. Older ranges are quite often 3 prong. |
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