Tig welder extension cord

what was the duty cycle of the unit at max? probably 20%

so for 2 minutes out of 10 the 12 gauge cord has to carry a 38 amp load

then the cable has eight minutes to cool down

What is the cost of the cable compared to the cost of the machine?

is it really worth saving the 20 dollars on the length of the extension cord to use 12 instead of 8 Gauge? comapred to the 1500 to

In fact if youre feeling extra cautious cut the breaker down to 40 amps and you should still never manage to pop it.

For what youre saving on cable the safety seems a better choice

The national electric code allows the conductors supplying an electric welder to be reduced according to the duty cycle. You didn't really need to use #6 conductors to wire in the circuit -- but if you ever replaced the welder with one that had a much higher duty cycle machine you might have to put in heavier wiring, and with what you used you'll never have to do that.

I'd probably make the extension cord out of #10 SE cable unless I just really needed something more flexible. (I think it's available in 10 gauge.) There would be nothing wrong with using #12 SJO (etc) cord here.

HTH, :-) Bob

Ratings for power cords are not the same as ratings for in the wall cables in conduits. The cable has more of a chance to cool from ambient air and dissipate the heat.

There is also a good point made by posters who mentioned duty cycle.

I am also not sure why there is a need for an extension cord. I would go with 10 gauge for the extension cord.

As has been noted, the NEC allows the use of undersized conductors on circuits feeding welders. This is ok in a commercial environment, but not so good in a residential environment. If there is a 50A outlet on the wall, someone will eventually try to connect a 50A load to it in a residential environment, so everything up to it really ought to be appropriately rated even if code doesn't require it. On the same idea, I would make my extension properly rated as well to allow for other uses in the future. Perhaps you'll get a kiln or heat treat furnace or something.

Pete C.

Besides worrying about the cord heating up, you should consider voltage drop. You don't want to have a sagging voltage characteristic when you are running the welder at maximum output. I haven't done the math, but you should. (And, of course, this has nothing to do with duty cycle,)

Actually you do this kind of thing every time you plug a table lamp wired with 18 gauge wire into a wall outlet protected by a 20 amp breaker. As others have mentioned, this is allowed by the NEC under certain circumstances. My only concern in your case would be voltage drop if your extension cord was too long. I also have a T/A 185 tig. It's on a cart along with a Thermal Dynamics 51 plasma cutter. The cart has a 30' 10 gauge cord that powers both the tig and the plasma cutter ( but not at the same time ). I've never had any problems with this setup. The 10 gauge cord never even gets warm, and neither unit seems to suffer from low voltage due to a voltage drop in the supply cord. Enjoy your new welder

That is not a very good analogy.

On Tue, 4 Sep 2007 13:40:14 -0700, with neither quill nor qualm, "42etus" quickly quoth:

Huh? A table lamp isn't drawing 152% of the cable's current rating when it's in use. A 150W bulb draws only 1.25A @ 120V. Standard current carrying capacity of an 18ga zip cord is 7A (16 in chassis use.)

If a cord gets hot in use, it's definitely overloaded and I'd install a larger gauge cable in its place before I'd use it again. So far, I've had no electrical fires in this lifetime.

=========================================================== Save the Endangered Bouillons from being cubed! ===========================================================

I had a similar problem and I put in about 25 feet of 8x3.

I must admit that I had to breathe rather deeply when I saw how much it was going to cost.

But now the weakest link in the chain is the guy doing the work! :-)oo

DOC

Jim Stewart wrote:

Jim --

Are you near water? Any decent-sized town with a boating presence will have a used marine equipment store and they just about always have shore power cables available. A 50A marine shore power cable will be just the ticket for your welder, and likely cost less at the boat surplus shop than it would to buy the parts new.

Regards,

Bob

Great suggestion. I'll check it out.

Sure isn't, because the 1 amp table lamp is on a 7 amp cord in a 15 amp circuit.

However, when running a welder on an extention cord, you want a cord capable of handling AT LEAST 120% of the expected load to reduce voltage drop. I like a good tec table 4-3 or 12-3 extention cord (15 or 20 amp capacity) to run things like table saws, light duty welders,pressure washers, etc. A lighter cord can sometimes prevent popping a fuse on startup because it limits the load - but not a good idea. My old repulsion start table saw would occaisionally pop a standard 15 amp fuse when started plegged into the wall. When on a 16 gauge cord 25 feet long it took longer to come up to speed but never popped a fuse. Went to using "slo-blow_ fusetrons - no more blown fuses.

Only if the lamp is running between 17 and 19 amps (just did a quick google and found a claim that 18ga is good for 16A -- what I'm saying here is based on the assumption that the info I found was accurate). If the lamp is rated for a 100W bulb, you're fine.

I'll have to look that one up...

Seems like a perfectly good analogy to me. The cord is sized considering the nature of the load, not the capacity of the circuit that's feeding it. The welder in question draws about 30A @ 30% duty cycle.

Unlike induction motors, most welders are tolerant of low input voltage. The 185T will operate on 208V circuits, so if it's being supplied by a typical 240V feed there'd have to be an awfully big drop to bother it.

exactly.

A welder does not have such startup issues.

I think you guys missed my point. The OP seemed to be concerned that he was going to have a cord rated at 25 amps protected by a 50 amp breaker. What I meant to point out is that it is very common and allowed by the NEC to have cords supplying appliances that are rated less than the breaker supplying the circuit. Most household appliances, toasters, lamps, radios, computers etc all have power supply cords that are not rated for the 20 amps that wall outlets are capable of supplying. Can you imagine your electric razor having a 12/3 SJO cord just because your outlet in the bathroom was on a circuit protected by a 20 amp breaker? That would make shaving each morning a real PITA.

My little "MIG" welder runs on a 15 amp circuit on 110 volts. On a 50 foot 16 guage cord at full output the voltage drops to about 96 volts. That reduces the maximum current of an already borderline welder significantly.(14% voltage drop roughly 28% power drop?????)

You're assuming the conditions of setting the duty cycle of the welder also apply to the duty cycle of the cord. I don't see *any* reason to believe that's going to be the case. When I see a duty cycle rating for an extension cord, I'll believe that it applies to it. In the mean time, I'll use a cord rated for the peak load that it will be called on to handle.

I'll agree that this is a different, and almost unrelated, question.

Duty cycle.

The same reason the wiring codes allow you to use smaller wire than indicated for welders. Gunner