Grounds

[orezok]

I got tired of pulling out an extension cord every time I needed to grind something on my welding table. I decided to add an outlet on the table. I extended a conduit to the table and made up a quad outlet.

But then I started thinking that the table is now grounded to the house circuit. The welder also grounds the table.

I was wondering if that 12GA ground wire will become a "heater" when I hit a piece of metal with 150 amps?

Has anyone had a problem with this?

 

[Shield Arc]

I had my table set up like that for a few years, until I made some changes. Never a problem, just keep your welding ground on the object you're welding, or like me 99% of the time I just clamp it to the table.

 

[boomer1025]

I got tired of pulling out an extension cord every time I needed to grind something on my welding table. I decided to add an outlet on the table. I extended a conduit to the table and made up a quad outlet.

But then I started thinking that the table is now grounded to the house circuit. The welder also grounds the table.

I was wondering if that 12GA ground wire will become a "heater" when I hit a piece of metal with 150 amps?

Has anyone had a problem with this?

Isolate the conduit from the welding table with a piece of heavy rubber/plastic or wood.

 

[orezok]

I'm not worried about the conduit, it can easily handle the amperage, it's the 12GA wire that worries me.

 

[dstig1]

Really? Steel is a much worse conductor than copper so will heat up a lot more with the same current flowing through it. Unless you were planning on huge conduit, I think you have that reversed.

In any case, it probably makes the most sense to just isolate the circuit and conduit from the table as previously noted. Use non-metallic conduit or Liquid-tite, perhaps and isolate the box as noted with a wood or plastic standoff so there is no contact.

I'm not sure if it would truly matter or not, but it seems a reasonable precaution....

 

[Shield Arc]

Take it from a guy who has burned up his share of electrical wiring when welding in factories. If your welding machine seems too cold, don't go turn it up, look and see if you attached the ground clamp first! :laughing:

 

[boomer1025]

I'm not worried about the conduit, it can easily handle the amperage, it's the 12GA wire that worries me.

If your putting a receptacle on the table, the ground wire for it runs back to the breaker box. Isolate the circuit and there shouldn't be any welding amperage bleeding back thru the circuit to the breaker box.

 

[orezok]

Really? Steel is a much worse conductor than copper so will heat up a lot more with the same current flowing through it. Unless you were planning on huge conduit, I think you have that reversed.

Exactly my point. The conduit due to it's cross section and high resistance will not be the problem. The 12 GA wire will.

Electricity like water takes the path of lease resistance.

 

[boomer1025]

Exactly my point. The conduit due to it's cross section and high resistance will not be the problem. The 12 GA wire will.

Electricity like water takes the path of lease resistance.

If you isolate the the circuit/conduit when you fasten it to the table. How is the welding current going to get to the 12ga wires ?? Take a short piece of heavy wall plastic pipe, split it and use it as a sleeve on the metal conduit where it fastens to the table. You now have an isolated circuit.

 

[orezok]

If you isolate the the circuit/conduit when you fasten it to the table. How is the welding current going to get to the 12ga wires ?? Take a short piece of heavy wall plastic pipe, split it and use it as a sleeve on the metal conduit where it fastens to the table. You now have an isolated circuit.

The conduit, the box and the 12GA ground wire are all bonded together.