I bought a 220V mig welder for home/garage use and need some advice on the outlet wiring.  There is an unused 220V dryer outlet (3-wire, which I now believe is a NEMA 10-30 receptacle) in the garage and my thinking was to simply replace the dryer outlet with a NEMA 6-50 receptacle which the welder will plug into.   I openned up the outlet and saw that the dryer plug is wired using the white wire instead of the bare ground wire (not used and not what I had expected).  The welder owner's manual says it needs to be wired to L1, L2, and ground. So, if I understand correctly, this is not just a simple replacement - I need to use the bare ground wire and stow the white wire?  Also, polarity of the red and black doesn't matter? I admit I don't understand why there is a difference (neutral/ground) when they are connected in the breaker panel (and don't really need to) but I want to get this right.   Thanks.

There is an unused 220V dryer outlet (3-wire, which I now believe is a NEMA 10-30 receptacle) in the garage and my thinking was to simply replace the dryer outlet with a NEMA 6-50 receptacle which the welder will plug into. A NEMA 10-30 and a 10-50 receptacle and plug have the same contact areas, and, hence, the same current carrying capacities. Since a welder is usually derated significantly, you can often install a 10-50 receptacle and cordset and retain the 10 AWG or 8 AWG feeder conductors. Or, since the 10-30 and 10-50 actually have the same capacity, anyway, just install a 10-30 cordset on your welder.

I admit I don't understand why there is a difference (neutral/ground) when they are connected in the breaker panel (and don't really need to) but I want to get this right. The bare ground is a safety ground. It is not intended to normally carry current. This keeps its integrity over long periods of time better, whereas the neutral can break down with shorts, surges, heating/cooling, etc. But all of this may be moot if you don't have wire larger than #10 to support your welder. If you keep the breaker at 30A, you should use a 30A receptacle and matching plug. The welder may or may not work with a 30A breaker. If you want a 40A or 50A breaker, you're going to need #8 or #6 copper wire instead. Perhaps you have an unused range circuit laying around....

Putting a 50A outlet on a 30A circuit is usually a bad thing and against code.... No, it isn't. Putting a 30A outlet on a 50A breaker would be against the Code. But you can always use beefier wire and receptacles on a smaller breaker. Gary

I bought a 220V mig welder for home/garage use and need some advice on the outlet wiring.  There is an unused 220V dryer outlet (3-wire, which I now believe is a NEMA 10-30 receptacle) in the garage and my thinking was to simply replace the dryer outlet with a NEMA 6-50 receptacle which the welder will plug into.   I openned up the outlet and saw that the dryer plug is wired using the white wire instead of the bare ground wire (not used and not what I had expected).  The welder owner's manual says it needs to be wired to L1, L2, and ground. So, if I understand correctly, this is not just a simple replacement - I need to use the bare ground wire and stow the white wire?  Also, polarity of the red and black doesn't matter? I admit I don't understand why there is a difference (neutral/ground) when they are connected in the breaker panel (and don't really need to) but I want to get this right.     Neutral (White) wires are grounded at the panel, but have the return for connected loads on them, like the 120V return from the dryer door light or the timers on the control panel.   Ground (bare) wires are not allowed to have any loads on them - but in the old days they would allow them to put the 120V door light load on the ground.  Nowadays (and especially on dryers and ranges in mobile homes and manufactured housing) they require a 4-pin grounding receptacle like the NEMA 14-30 or 14-50 with separate ground and neutral pins.     You can do the swap simply enough by removing the NEMA 10-30 and put a  6-50 receptacle there, but you can not bump up the breaker to a 50A unless the wire in the wall is sized for it - though with many smaller home welders they don't draw more than 30A anyways.  If the ground wire is connected at the panel now (and it better be...) you can cap the white wire and connect the receptacle to the bare wire.     Red and Black polarity don't matter, as long as you get them on the right pins.  The only time I can think of where it matters is when you're working with 3-phase systems, and you need to keep the rotation correct and/or track a manufactured phase or high-leg.   That, and where they run 2-wire+ground Romex for a straight 220V circuit - they are supposed to tape the white wire at each end to signify it is a hot circuit.   For people that do use their dryer outlet for a dryer (Sorry, sucks to have an All-Electric house when you get the power bill...) you could make a corded adapter with a NEMA 10-30 cord-set from the home center and a 6-50 receptacle in a box, for something like this the difference between 'ground' and 'neutral' is insignificant as long as they are connected through.              

I bought a 220V mig welder for home/garage use and need some advice on the outlet wiring.  There is an unused 220V dryer outlet (3-wire, which I now believe is a NEMA 10-30 receptacle) in the garage and my thinking was to simply replace the dryer outlet with a NEMA 6-50 receptacle which the welder will plug into.   You have an older three-wire receptacle for dryers.  There used to be a code exception for dryers that allowed them to return small amounts of current thru the ground wire. This is probably why the person who wired your recptacle used the white rather than the bare wire to the third (not red, not black) connection to the dryer. You need to inspect to see if the bare wire is indeed terminated to ground inside the panelboard before you connect to it.  If it isn't, and you don't want to work inside the panelboard, then you could hire somebody to terminate it there, or tag the existing white wire at your recptacle end as green.   Whoever wired the dryer realized that the code exception was going away and pulled four conductor wire to it, which is in general a good thing. What size breaker feeds your receptacle? It should be 30 amps if the wire is number ten.  Check the breaker size and the wire size, which will be printed on it. You can either put a (smaller) cordest on the welder that fits the existing receptacle, or put a receptacle on the wall that fits the cord on the welder, but you cannot increase the size of the breaker in the panel unless you change the conductor size. Jim ===================================       please reply to: JRR(zero) at watson dot ibm dot com ===================================