Extension Cord Size.

How long a cord are you intending to use?

Ron,

Normally 6GA would be minimum for 220V/50A and depending on the length of run 4GA is probably better (anything over 25 ft I'd go 4 GA). You'll likely struggle to find a ready made extension cord, best bet maybe to go to a home depot/electrical wholesaler and purchase wire off the roll and the correct plugs. Make sure you get a multi strand copper wire (not aluminum), trouble is all this may ending costing nearly as much as the proper welding cable (which is usually very fine strands of copper for the high current demand application)

Good luck,
Julian

Hi Ron. What type of conditions will the cable be subjected to? Concrete/wood construction area? Indoors? Outdoors? Wet/dry?
Will

Why not just extend its present wiring in conduit to where the new location is needed????

" What type of conditions will the cable be subjected to? Concrete/wood construction area? Indoors? Outdoors? Wet/dry?"

Concrete floor, wood rafters, indoors, dry ...

Its a construction project Rye Playland Bathhouse, its a resotration of a 1920's Historical Building. It happens to be a very long building right on the beach were we have a lot pipe welding to do. I need about 250' in each direction from the 50 amp 220 disconnect I gave the electrician to connect at the center of the building ..thats the only location for power are this time. I have Cables we normally use but they are 50' long with 220 50 amp ends on them we made in the shop. I would say 2 - 100' cables should do and the rest we would use welding lead. But what sepcifically do I ask for at the Electrical Supply ?


Ron

I do not know if it is an option or not, but do you know of anyone that has a portable welder say, that is normally mounted to a mechanics truck? The Millers that we have are self contained and could be taken off a truck and mounted on a dolly to roll around. I know that some run on diesel and others run on gasoline. Of course they will bring carbon monoxide to the equation, but if there is proper ventilation, you would not have to purchase a bunch of copper for a specific job. These welders are not very large either. You could roll the welder right up to the area you need to weld.

Mark

Ron,

If your welder draws 40 amps on the primary (high voltage side) and the voltage at the receptacle is 230 volts, then the voltage drop is:

200', #6 wire = 2.9% or 6.7 volts
250', #6 wire = 3.6% or 8.4 volts
250', #4 wire = 2.3% or 5.3 volts

The length above is from the receptacle to the welder (total of the extension cords + the welder cord), and does not include the voltage drop between the receptacle and the main panel (or to the transformer). Wire is copper.

The #6 wire at 250' is marginal but should work, but if your welder has any electronic controls, then use the #4 cable (as Julian suggested). It's a lot cheaper to buy the next size larger cable than to buy a new welder.

The cable is referred to as "6/3 (or 4/3) SO cord". The 6/3 means #6 wire, 3 conductors. SOO and SOOW cord are equivalent. Figure on $$$ per foot.

Your jobsite probably has 240 volts, which will reduce the voltage drop slightly.

One other consideration is if the building has three phase power. If it does, the available voltage may only be 208 volts. If it is 208 volts, then use the #4 cable.

John

Check the ratings of the "SO" cable. They carry a lower rating than standard cables. 6/3 SO/SOO cable has a rating of 55amps as opposed to 60amps in regular cable.
I suggest 4ga/3c (2 hot conductors and a ground) to cover for the voltage drop as mentioned earlier.
You mentioned it was 220v, so I'm assuming it's a single phase welder.
Will

If your need is temporary, rent it. When I worked down under (transit) in NYC everyone that rented welders rented extra cable too. Heavy stuff too. Gasoline engines were forbidden in the tunnels and diesels choked everyone out.

quote:

6/3 SO/SOO cable has a rating of 55amps as opposed to 60amps in regular cable.

By "standard cable", do you mean romex or THHN building wire? Both of those are not nearly as flexible as SO/SOO/SOW cord. Romex and THHN typically have 7 or 19 strands and #6 cord has ~100 strands.

Basically, #6 cu wire is #6 cu wire. You can't change its properties to increase the ampacity (ampere carrying capacity). Increasing the current in a wire increases the wire's temperature, which, in turn, increases voltage drop.

Type SO/SOO/SOOW cord/cable typically has an insulation temperature rating of 30*C (86*F). THHN building wire will carry 55 amps at 60*C (140*F), 65 amps at 75*C (167*F), and 75 amps at 95*C (194*F). 75 amps through #6 wire just about doubles the voltage and almost boils water.

As Larryw suggested, check out renting what you need.

John

quote:

Basically, #6 cu wire is #6 cu wire

The coatings of the cable will change the ampacities. I checked and flexible cable (SO, SOO) #6 with 2 current carrying conductors is rated at 55amps and #6 w/ 3 current carrying conductors is only rated at 45amps.Different than ratings of #6 teck or AC90 armoured cable (60amps).
Will

Will got it ... the SO/SOO cable is what I need.

Mark I have plenty of equipment gas,Mig,tig,digital,..the project has mutliple issues, one the nieghbors are complaining about the noise so gas and deisel are out, the digital machine they will steal to expensive ( it adjust to any voltage and voltage drop also electric), this job is quiet at night secluded the kids hanging out will steal the copper welding lead cable. The enxtension cord we can wire up and leave it hot and tie wrap it to the pipe hangers so we have the cord where we need it.

Larryw I also work the subway tunnels another unique job. The issue with renting if they steal it you have to pay for it anyways, the cords I will use again so its not the money .. just the cord will be less money then welding leads for sure.

Thanks for the help guys

Ron