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Hi Jeff, a #10 AWG 30 amp 220V cord should be more than enough to cover the minimal voltage drop you would see over 30ft..as the distance increase's the voltage drops..the wattage or load stays the same so the current goes up..thats why we increase the conductor size..its a triangle.. A squared + B squared = C squaredI want more reach with my welder. It only has about a 12 ft cord and I'd like to add a 25 or 30 ft extension cord to it. Will a 30 amp cord be enough for welding on setting 1 or 2 of 5? The welder is a Hobart 220V.

Jeff

Thanks, Mike.

Pythagorean theorem?

Pythagorean theorem?

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that would be the one..basic electricityPythagorean theorem?

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I think the pythagorean theoram had to do with the sides of a right triangle.that would be the one..basic electricity

Mr. Ohm used his digital multimeter to measure volts, current, and resistance.

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HeHe..Mr Ohm must be working on a different site than me.. i use Mr Fluke for my digital..Mr. Ohm used his digital multimeter to measure volts, current, and resistance.

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72,363 Posts

Remember to alway unwind the lead DO NOT COIL the lead up even on short runs

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7,323 Posts

:confused0006:Remember to alway unwind the lead DO NOT COIL the lead up even on short runs

I've been using my shop welder

The wire gauge and length is going to determine the voltage drop. You need to assure sufficient voltage at the machine when it's under load. And you can't measure the voltage at the receptacle, with the machine not plugged in - it will usually be OK then, even if you have a problem.

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3,283 Posts

I have another one that is either #8 or #6 but it is too heavy to tug around...

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How so? The cord is a resistor, and it causes the voltage drop to the welder. The current cannot go up with more resistance in the circuit. Voltage drops, current drops (at the same setting) and wattage drops as a result. Watts is voltage times amps.as the distance increase's the voltage drops..the wattage or load stays the same so the current goes up..

But I am far from an expert on how input voltage affects welding machines. Or for that matter how it affects transformer machines vs. inverter machines.

Why not lengthen the torch and ground leads? (Other than it may be more work and expense.) That might be a better solution. I think it's a lot more convenient too.

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12,101 Posts

The reason it happens on a motor is due to back-EMF. With lower input voltage, the motor turns slower. As it turns slower, the back EMF decreases and you get more current through the windings. A welder does not act like a generator, so no back-EMF is produced. If you increase cord resistance, you decrease current and increase voltage drop (ohm's law). So wattage decreases at the welder with the same setting. If you want the same wattage, you have to turn the welder up, so current increases.Whether the current increases as the voltage decreases depends on the load you are running. With an electric motor that will happen. Not sure about a welder - I think it will when you crank up the output current as reaction to the drop in voltage. Think constant power to get a job done. On the other hand most welders are described as "constant current" machines.

But I am far from an expert on how input voltage affects welding machines. Or for that matter how it affects transformer machines vs. inverter machines.

That said, unless you're welding at fairly high current I don't think a 10 gauge cord is going to affect it much. I use a long 10 gauge cord on a MIG welder that we weld 1/8" steel with. Heck, most shops are wired with 12 gauge wire from one end to the other so it's kinda like plugging in across the shop. I assume this is a 110V welder like the one we use.

"If you want the same wattage, you have to turn the welder up, so current increases."

I think we agree on this.

The electric motor is the same way, but it does it by itself.

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I error-ed on the side of caution and went bigger wire.

I don't know much about what you guys are discussing but bought the 25 ft, 30 A cord.

Jeff

Jeff

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The key phase being..LOAD stays the same..same amount of output from the welder..input current will rise.How so? The cord is a resistor, and it causes the voltage drop to the welder. The current cannot go up with more resistance in the circuit. Voltage drops, current drops (at the same setting) and wattage drops as a result. Watts is voltage times amps.

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That only applys to a DC motor..the only ways to change the speed of a AC motor is a change in the number of poles or frequency. thats why we have Variable Frequency drives for conveyors and large aerial coolers in plantsWith lower input voltage, the motor turns slower.

Jemo, are we talking 120V or 240V welder here?

It's a 240V welder. Hobart Handler 180

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