return lead 2 clamps structure and item?

Question

Hello all

Yup it's pouring with rain and there's an emergency welding job which has to be done...

Does it help to have a return lead with two clamps

- one attached securely to the structure (in this case the barge you are on) before you turn on the generator / welding-machine

- the other the clamp you attach to the workpiece

The reason would be to avoid being electrocuted all the time as you try to move the return / "earth" clamp.

Surely if there is a permanent attachment of the return clamp to the barge, the "moveable" return-clamp would always be at the potential of the barge and you couldn't get shocked when you transfer your working return-clamp?

So that both the "new" piece of metal and the "existing structure" are both tied to "ground" potential and you don't have to be careful about which side you strike-up on in avoiding getting shocked. Because the "free" / "floating" return clamp can be put on the "new" part.

Have I got this right?

Would you make-up a short length of cable between male and female "bayonet" connectors, with a juntion in the short length branching-off to the clamp you attach to the main structure for the duration the generator is on?

Thinking is - you could split any pair of bayonet connectors in your welding cable run where there is a good place to attach to the barge / structure, and insert this fitment and get that good enduring earthing attachment.

???

Thanks in advance, Rich S

Jim Wilkins · Accepted Answer

The "ground" welding lead isn't really grounded, the welding circuit is isolated from the power cord ground. Otherwise a bad clamp connection would force your hundreds of Amps of welding current to return through the power cord and burn it up.

You would only have welding voltage on the "ground" clamp if you yank it loose while the electrode is stuck to the work. When it's not clamped to the work you might measure voltage on it due to capacitive coupling between the primary and secondary transformer windings. A sensitive clamp-on ammeter would show this small leakage current when the clamp is grounded.

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"The welding circuit is not connected to ground within the welding machine, but is isolated from ground." "The welding cable does not bring a ground connection to the workpiece."

Richard Smith · Answer

I repeatedly used the terms "return clamp" and "return lead". Hopefully I am thinking in the right way. You are definitely the expert on the electrical stuff.

So - would my "2 return clamps" idea work, so long as you are not connected to the stinger potential through being soaked with water, in avoiding being electrically shocked?

Rich S

Jim Wilkins · Answer

I think your idea is good as long as either return lead and clamping location can handle the full welding current, but I don't know anything about the rules for welding in the rain, or wet ditches.

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One source I looked at suggested painting regular electrodes with spar varnish. Another said go with acetylene.

Richard Smith · Answer

You are not supposed to weld in the pouring rain * metallurgical concerns, including hydrogen pick-up * safety - electric shocks In reality - you are the welder and you need to be able to get everyone out of a jam.

Jim Wilkins · Answer

"Employers might address this hazard by covering or enclosing the  entire work area to prevent the electrical equipment from coming in  contact with the precipitation, the provision of appropriate personal  protective equipment, such as rubber gloves and boots intended for  this purpose, or other methods of abatement as appropriate to the  particular circumstance of a given task." I have a small pop-up canopy to work under in wet weather. I can walk  it around by myself by lifting it in the center with a push broom, so  I can set it up in a clear space away from the work and reposition it  as needed. The tautline hitch and prusik knot are very handy for guying a tarp or  canopy to whatever is nearby, without needing any other rope  tightening devices.

John B. Slocomb · Answer

Just as a comment, when working on contracts to build hydrocarbon carrying pipelines the insurance company forbid the welding on pipelines when it rained. To avoid delays we suggested a tent over the pipeline but they still said no, no welding on even a damp pipe.

Granted that insurance companies are a bit sensitive about hydrocarbon carrying pipelines but still...

Jim Wilkins · Answer

"As a RULE we do not lay in a stream of water or mud to weld, on a  rare occasion a thunderstorm may hit while you are finishing a weld  and you get a tent or some kind of cover if the weld cannot be  stopped, otherwise you cab up until the weld can be made in the dry.  If the weld can be stopped and a wrap placed on it, we will wait for  the rain to stop."

Richard Smith · Answer

We have "island" weather here - very variable.  Not "continental" weather with big long periods of a particular type of condition.  So have to accept drizzle, etc. Structural steels are deliberately made to be not sensitive to extra hydrogen, etc. Need welding system which continues to run right in adverse conditions - so right choice of SMAW.

Jim Wilkins · Answer

I was searching for authoritative advice from shipyard or pipeline welders, and that's what I found. John B. Slocomb is an expert on the energy industry in Southeast Asia, where it more than drizzles.

Please understand that this is a 2004 laptop running XP, with dialup internet since I don't have cable TV, so searching is rather slow and I can't view incompatible websites. I haven't yet properly configured my flea market Win 7 and 10 laptops to post to newsgroups, and as you can see this one still works.

Richard Smith · Answer

Hi Jim Yes. Laptop etc. - sounds like some very remote part - of the US? Regards, Rich S

Jim Wilkins · Answer

I can hear sled dogs howling at night.

return lead 2 clamps structure and item?

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