220V Extension Cord for Welding

[samstu]

I'm not an electrician, but it's my understanding that wire size for welders can undersized or at least needs no over-sizing due to the low effective duty cycle of most welders and operators. Lots of time for cooling occurs in a non-production environment.

You can find this in article 630 of national electrical code. But in brief, a low duty cycle welder only needs wire capable of carrying 0.55 times the rated max input value of the welder. Local codes and your own comfort level may vary.

I suspect most home welder wiring is over-sized.

 

[G-ManBart]

I'm not an electrician, but it's my understanding that wire size for welders can undersized or at least needs no over-sizing due to the low effective duty cycle of most welders and operators. Lots of time for cooling occurs in a non-production environment.

You can find this in article 630 of national electrical code. But in brief, a low duty cycle welder only needs wire capable of carrying 0.55 times the rated max input value of the welder. Local codes and your own comfort level may vary.

I suspect most home welder wiring is over-sized.

That is true, but that's a slightly different topic than what the OP was asking about. Sizing the conductors and breaker covers the safety aspect...essentially heat as you mention. The OP was worried there would be too much voltage loss due to the length of the cable. Most charts start at 50ft, so under that it's rarely a concern.

 

[erikmannie]

I'm not an electrician, but it's my understanding that wire size for welders can undersized or at least needs no over-sizing due to the low effective duty cycle of most welders and operators. Lots of time for cooling occurs in a non-production environment.

You can find this in article 630 of national electrical code. But in brief, a low duty cycle welder only needs wire capable of carrying 0.55 times the rated max input value of the welder. Local codes and your own comfort level may vary.

I suspect most home welder wiring is over-sized.

A great deal of the welding that I do is practicing on coupons, and sometimes with the machine at max current. As such, a large number of coupons are prepped & ready to roll. Under these circumstances, the machine gets quite a workout.

So far, I have never had a machine switch off because I hit the duty cycle limit. I often wonder if, once an operator hits the limit on a duty cycle, the machine is engineered to “auto-shutdown” and cool off.

 

[G-ManBart]

A great deal of the welding that I do is practicing on coupons, and sometimes with the machine at max current. As such, a large number of coupons are prepped & ready to roll. Under these circumstances, the machine gets quite a workout.

So far, I have never had a machine switch off because I hit the duty cycle limit. I often wonder if, once an operator hits the limit on a duty cycle, the machine is engineered to “auto-shutdown” and cool off.

It really depends on the machine. Most modern welders will have a thermal protection circuit which shuts off welding current but keeps the machine on with the fan running if it gets too hot. I'm sure you could get all sorts of arguments on a welding forum over whether that only happens if you exceed the duty cycle a lot or just a little, etc. In practice, the actual duty cycle will vary with ambient temperature as well, so there's the book duty cycle, the actual duty cycle and when the machine will cut welding output, and the three may not match.

Mr. Tig over on Weld.com did a video on duty cycle with a bunch of smaller/less expensive welders and most of them would exceed their listed duty cycles before thermal cutoff. It's almost hard to watch!

 

[Winegrower]

I apologize for the detour, ignore as needed. A friend brought his freshman high schooler over as he was interested in electricity/electronics. I took him through voltage, current, resistance, power and energy…he’s very bright, caught on immediately, and could solve problems like “how much horsepower can you get from a 120V 15A circuit”. I gave him an old HP3478 DVM and he left happy, and I told him he now knows more about electricity than 99% of the people on earth.

It is always surprising how little most folks really know about the basics, since who really tries to teach this? I got nothing in high school and college level courses can leave you with memorized Maxwell’s equations, but good luck doing anything with that.

Ah, I must be getting old.