American Welding Society Forum
Well, I just ran an extension off the dryer circuit into the garage of my home to power my new 220V TIG welder. The dryer circuit is the normal 30 amps, and it had two hots and a neutral connected. Ground wasn't even connected (which is probably because the junction box is plastic rather than metal). However, the ground wire was still there. So, I piggy-backed two hots and ground to a 220V outlet on the other side of the wall (which is the garage, took 2' of house wiring). I connected two hots and ground. I plugged the welder up and powered it on, and it came on.
However, I'm still wondering if I should be running two hots and ground OR two hots and neutral. Does anyone familiar with residential wiring know the answer?
Additional: I will not advise on this one, other than;
Just because the existing piece of equipment (the dryer) did not require a ground, does not mean the new piece of equipment (your Yellow Sub) does not require a ground.
OK, I just checked a second book, and found the same answer. 220V only = 2 hots + ground, 220V + 110V = 2 hots + neutral (plus ground if the equipment has a ground connection OR the junction box is metal rather than plastic).
So, 2 hots + ground is the correct answer...I actually wired this correctly. I guess I was just a little thrown because the dryer doesn't use a ground connection, only neutral. Comforting thought, eh? You're trying to dry your drawers and you get your hair curled instead!
You should try to hook up the ground as well,the ground is there in case something happens to your neutral like a cut in the wire melted wire ect. The ground and the neutral serve the same purpose and go to the same place. You should however check in your welders manual regarding the correct breaker size and correct gauge wire to make sure it is suitable to power your welder. You could make your wire to your dryer very hot under heavy welding loads. That is why it is important to have the correct gauge for the application. It should give you what gauge you should have for the length of your wire from your panel to the machine.
Most dryers are actually mixed 220 (the heater) and 110 (the motor and any lamps) devices. Hence two hots and a neutral is the technically correct answer. Most appliances I have seen come with neutral connected to the chassis internally so they ground through the neutral (which ultimately goes to ground). The difference between neutral and ground is- neutral is used to absorb the difference between the load on the two hot leads so assuming a 110 motor and 220 heater- if the drier is hot enough (heater off) but the motor is running all the motors current will be between one hot and the neutral and the neutral will be carrying a current of several amps; ground on the other hand should never carry a current (save for bleedoff of static or such) maximum of a few milliamps. Any leakage of current from a hot into a ground would be a fault and would trip a ground fault interupter if the device was served by one. Since appliances would feed the fault current back into the neutral the GFI would be fooled. The documentation with your welder should indicate if it requires a seperate ground. If it has four pins on it's plug that's a strong indicator. If so you indicate an unconnected ground in the dryer box, you can easily extend that to the welder, check that it is connected to the ground buss in the breaker box (carefully). Standard disclaimer- any doubts consult your friendly local electrician
Bill has given some good advice, everyone has for that matter, (I just can't see all the names while I'm in this reply box).
I just wanted to explain...in most residential services each hot lead carries 120 volts and at any given time one is 120 V+ and one is 120 V- The voltage difference between the two is 240 V. If you require 240 V, the current is carried between the two hot conductors. As long nothing else makes contact with the wires, the neutral and the ground do nothing.
Now, many 240 V appliances also use 120 V sub-circuits to run light bulbs, fan motors, and such. Those get their power by tapping into one of the 120 V lines and are connected to ground through the neutral line. In that case the neutral conductor carries the same amount of current through it as the tap into the 120 V conductor does because they make up the 120V circuit.
Even though the neutral and the ground connect to the same place, that is the earth, the neutral is designed to carry current. The ground has the capacity to carry the current but is not supposed to act as a conductor unless something goes wrong and electricity is not flowing where it is supposed to. Since all those hard working electrons are trying to get back to the earth where they originally came from, they will take the easiest path to it. So the ground conductor is supposed to provide a better path than the human body is.
IF insulation never breaks, or screws never came loose, then a ground conductor would never be needed for safety. However, a neutral conductor is always needed if you want 120 volts. Some 120V appliances have 2 prong plugs because they have double the amount of insulation and no metal parts that can become energized. They are designed that way. A 3 prong 120V appliance shouldn't shock you if the ground prong was missing IF everything is in good condition. But if not in good condition, the operator can become the path to ground, so the protection needs to be provided. Some 240V appliances do in fact require only 3 wires, 2 hots and 1 neutral (which is connected to ground). Same for them as the double insulated 120 V appliances, they were designed to be safe to use that way. But if the appliance requires a separate ground, it is best to provide it. Without it, you won't get shocked if everything is operating correctly but if anything goes wrong......
So the best advice is to follow the manufacturer's installation instructions. If you're not sure about them, an electrician's fee is cheaper than a funeral and cheaper than replacing a burnt building.
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