Hi All, Need your input on the extension cord that I made for my welder (Lincoln squarewave 175). I did my reseearch on this site and here's what I did. I made it out of 10-3 wire (rated for 600 volts) - extension cord is 100 feet. The male plug is 220v 30amps and made so that it will plug into my clothes dryer outlet. The female receptacle is 220v 30amp outlet receptacle (receptacle with a rectangle metal box). Does this sound right to you? Is there a higher chance of getting shocked because my female end is made of metal (male plug housing is plastic/rubber). Thanks for your advice! Tom
Biigest thing is to make sure you have a grounded style plug. If the third pin is round, you are good to go. If it is a blade, you have the older style with neutral rather than ground, not good. Metal housing on the female end should not make any difference, it will be somwwhat more resistant to damage than the plastic versions.
"Tom" wrote in message news: snipped-for-privacy@f14g2000cwb.googlegroups.com... | Hi All, | Need your input on the extension cord that I made for my welder | (Lincoln squarewave 175). I did my reseearch on this site and here's | what I did. I made it out of 10-3 wire (rated for 600 volts) - | extension cord is 100 feet. The male plug is 220v 30amps and made so | that it will plug into my clothes dryer outlet. The female receptacle | is 220v 30amp outlet receptacle (receptacle with a rectangle metal | box). Does this sound right to you? Is there a higher chance of getting | shocked because my female end is made of metal (male plug housing is | plastic/rubber). Thanks for your advice! | Tom
The biggest issue should be the size of the wire, and everything else is secondary. 30 amps through 10 gauge wire will get you a voltage drop of about seven volts. If you have closer to 230 volts in your house, it might not be a big deal, but that will make your extension cord really hot. 8 ga will get you about a 5 volt drop, which is more tolerable. Ref
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Plugging that result into the power formula, the 10 ga cable will put out 225 watts worth of heat and the 8 ga will put out 141 watts worth of heat.
I'd feel a whole lot more comfortable with the 8 ga wire than the ten, but what you've got there will work and I think it is "legal." I'd avoid using it when it's hot out, though, but that's just me.
Oh, and don't coil up the wire on the floor when you're welding. Lay it out either in a wad or spread out all over the floor.
Thanks for your repsonse everyone. I'm going to be welding thin sheet metal/sheet aluminum so I don't think I'll be at full amperage. Hopefully I won't have any problems with drop in amperage.
Duty time may be a problem with the 10 ga. wire, voltage drop and heat in the wire would be a problem with thick or long welds. Allow adequate time for the system to cool between beads.
Hello group. Can someone clarify something for me: On my "ancient" 3 prong 220v dryer circuit, isn't the neutral supposed to be connected to ground at the panel? If it is , what are the problems with using it as safety ground for a purely 220v buzz box?
I would be surprised is there is neutral, but no ground. All appliances are supposed to have their frame connected to ground and not neutral.
Circuits where 220V and neutral are needed, like some stoves that need both 120v and 220v, usually are served by 4 prong plugs, 2 hots, a neutral and ground.
So, I think that your outlet does not have neutral, but has ground. If you have an ohmmeter, check if there is conductivity between that third prong on your plug, and the frame of your dryer. If so, it is a safety ground.
Ground is a non current carrying conductor and neutral is for carrying current.
Iggy is correct for the newer dryers, they run 2 hots, and a GROUND with the motor running on 220 OR they run 4 wire (2 hots, neutral, and ground) Older dryers were allowed to run 2 hots and a neutral. And he is also correct in that ground connections should carry no current under normal conditions.
The problem you get into is that any coductor carrying a current has a voltage drop. The 120 volt motor on the dryer is running on one hot and the neutral. Result is that the neutral on the dryer is running aboove ground at the breaker pannel. This is minor compared to when something goes wrong with the heater circuits, you can get some serious voltage over at the dryer. On the older dryers, there is a jumper to allow you to connect neutral to the frame ground on the dryer. It is usually left unjumpered.
Remember - in the fuse / breaker box - both the Green and White - ground and Neutral wires are attached to the same Neutral-Ground point that is cabled to the earth.
The real issue - is the Ground or Neutral cable capable of the current that is needed.
Martin - Not an Electrician - but knows a lot about it - former professor of it. Martin Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH, NRA Life NRA Second Amendment Task Force Charter Founder
(and looking from over from "the rest of the world where we have 240V 13A off any wall-socket, so always have "Live", "Neutral" and "Earth"...)
In N.Am, to get 220V by using two 110V supplies 180deg out of phase...
You need three wires.
110V one-angle, 110V 180deg opposite angle and Earth.
There is no neutral and physically there cannot be. It has no meaning or existence that I can see of... ???
The Earth is at the potential of the Earth and any current down it is a fault... (?)
So in effect you are pushing current at 110V down one live and pulling it at 110V down the other live, giving an aggregate 220V of potential drop at the machine you are operating.
And another way of saying the same thing is that the current path is out along one 110V line and back down the 180deg-opposite 110V line. Of course, this is alternating current so you have this alternating push-pull.
But as I reckoned earlier, you rightly have three wires total -- am I right?
So contrasting, in "the rest of the world" the current path is from live to neutral, with neutral tending to Earth potential given a little "backpressure" of potential due to the small resistance of the copper wire (?), and the entire potential on which the machine is operating is between the Live potential of 240V and the Neutral/Earth potential of zero V.
Have I got this right?
BTW - just in case anyone is thinking we are getting at the N.Am system, we use a similar concept on London Underground tube trains. It has two railway rails which are not connected to any power circuit (they do carry the "Automatic Train Protection system" signaling signals on most lines) and two electrical rails - so that's four bars of metal in total. I think this is right - the middle rail is at
+440V DC and the side rail is at -220V DC. So for a total of 660V of potential available to the train the maximum voltage to be insulated is 440V. And there are no stray Earth currents causing cathodic corrosion problems of the tunnel lining, seeing as the out and return current paths are both isolated conductors...
Richard Smith
"Mart> Remember - in the fuse / breaker box - both the Green and White - ground and Neutral
Well, some appliances require both 110v and 220v but old circuits (like mine) might only provide three conductors. In the US the new (1996) National Electrical Code seems to require separate ground and neutral so you need 4 conductors, but prior to that, stove and dryers could use ground as neutral.
here is a quote from:
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[Important Note: In the US, the NEC used to permit a circuit similar to (2) be used for stoves and dryers - namely, three conductor wiring, with a ground wire doing dual duty as a neutral. As of the 1996 revision to the NEC, this is NO LONGER PERMITTED.]
No, in this case that is NOT the issue. The welder runs on 220 volts, there is (should be) NO CURRENT in the white or green conductor. By your logic, you could use some #30 wire for the neutral. (!!!) NOT!! For this installation, the 3rd wire is to provide protection for the operator in case of a fault in the machine. If there is a major fault (hot to case), the ground wire WILL conduct current and blow the breaker. Even if it is undersized somewhat, it will still blow the breaker. The other issue is leakage current (usually bad insulation in the windings) A green wire attached to the case will hold the case at ground potential, protecting the operator. The resulting current will heat up the core and eventually wipe out the welder but keeping the operator safe is the first priority.
As for the neutral versus ground issue: if there are no 110 volt loads, there is no current in the neutral and the system is electrically equivilent to a grounded system. Not code legal but equivilent. Add in any regular (or parasitic) 110 volt loads and the the neutral is at a different potential than the ground lead. NEC is set up to handle a wide range of variation in appliance design.
On a simalr note: the NEC allows dedicated welder circuits to be run with larger breakers than normal for a given size of wire since welders do not draw continuous current. For hobbist use, I'm OK with somewhat undersized extension cords but adament about not doing this for imbedded (in the wall) wiring. The extension cord will get hot, but it won't be passed on to the next buyer of the house like the breaker panel will be.
Net: Before you cheap out and (mis)use an exist> Remember - in the fuse / breaker box - both the Green and White - ground > and Neutral
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