New here so, Hi all. This is a bit of a puzzle for me so I'm hoping someone here has either seen it before or can explain what is going on. I'll explain what happened today then ask for opinion.
My welder is a very simple Cigweld Transmig 130 Twin which is Gas / Gasless on a 10 Amp power input. It hasn't had a lot of use and for the last 10 years or so I've been successfully using 0.8 mm gasless wire after returning my bottle due to spending near $1000 on bottle rental and using less than an E size bottle of gas. We all know about that. Anyway BOC's new "D Plan" has encouraged me to go back to gas (and also Oxy- Acetylene) as it is now what I consider to be affordable for the home workshop. Plus I have a backlog of jobs to do.
I've done a bit of welding in my big shed before but always either on the concrete floor or with my work supported on portable trestles. The shed is a Ranbuild portal frame steel shed which was wired to the house meter board, by a licenced sparky, with a sub-main and circuit breakers for lights and power. Both use an ELCB or RCD for isolation and protection. All wiring in proximity to the shed structure is inside conduit and the shed itself is connected to the earth wires as you'd expect.
Today I started building a trolley for the welder and bottle and since it is only a small project, I was working on a bench which is steel framed and connected structurally and electrically to the shed frames. The bench top is yellow tongue flooring (insulated from shed) and the first couple of welds I did were all good with no problems once I blew the insect nests out of the gas line. Bloody mud wasps. The surprise for me occurred when I held the first component in the engineers vice which is bolted through the timber and metal frame, and so is electrically connected to the shed.
As I went to attach the work clamp to the job sparks jumped across the gap. This stopped once the clamp was on but it didn't seem right to me as I've never ever seen it happen before. I removed the clamp with more sparking and touched the clamp to the bench frame itself and sure enough it sparked again leaving a black scorch mark on the zincalume coating. The welder was turned on obviously but the torch was sitting on the timber bench with the trigger free. I felt that had I held some electrode wire in the work clamp I could have welded to the bench frame with the torch turned off and sitting away from anyhting.
I then put the work clamp down on the timber bench (insulated from everything) and picked up the torch to test it. I could strike an arc on the work without the work clamp completing the circuit. Whether or not I could have actually welded or not I'm not sure as I didn't try. The circuit breakers didn't trip out. I didn't die or even get a tingle so I just continued to weld for a while before calling it quits for the day.
The only explanation I can see is that the welder was somehow using the 240V electrical earth to complete the weld circuit and it could do it from both electrode and work clamp. The ground, as in dirt, gravel and rocks, is extremely wet due to several days of heavy rain but I just don't think this should happen and until I hear otherwise, I don't really like it.
Any thoughts or explanations would be greatly appreciated.
Read the full thread at metalworkforums.com...
My welder is a very simple Cigweld Transmig 130 Twin which is Gas / Gasless on a 10 Amp power input. It hasn't had a lot of use and for the last 10 years or so I've been successfully using 0.8 mm gasless wire after returning my bottle due to spending near $1000 on bottle rental and using less than an E size bottle of gas. We all know about that. Anyway BOC's new "D Plan" has encouraged me to go back to gas (and also Oxy- Acetylene) as it is now what I consider to be affordable for the home workshop. Plus I have a backlog of jobs to do.
I've done a bit of welding in my big shed before but always either on the concrete floor or with my work supported on portable trestles. The shed is a Ranbuild portal frame steel shed which was wired to the house meter board, by a licenced sparky, with a sub-main and circuit breakers for lights and power. Both use an ELCB or RCD for isolation and protection. All wiring in proximity to the shed structure is inside conduit and the shed itself is connected to the earth wires as you'd expect.
Today I started building a trolley for the welder and bottle and since it is only a small project, I was working on a bench which is steel framed and connected structurally and electrically to the shed frames. The bench top is yellow tongue flooring (insulated from shed) and the first couple of welds I did were all good with no problems once I blew the insect nests out of the gas line. Bloody mud wasps. The surprise for me occurred when I held the first component in the engineers vice which is bolted through the timber and metal frame, and so is electrically connected to the shed.
As I went to attach the work clamp to the job sparks jumped across the gap. This stopped once the clamp was on but it didn't seem right to me as I've never ever seen it happen before. I removed the clamp with more sparking and touched the clamp to the bench frame itself and sure enough it sparked again leaving a black scorch mark on the zincalume coating. The welder was turned on obviously but the torch was sitting on the timber bench with the trigger free. I felt that had I held some electrode wire in the work clamp I could have welded to the bench frame with the torch turned off and sitting away from anyhting.
I then put the work clamp down on the timber bench (insulated from everything) and picked up the torch to test it. I could strike an arc on the work without the work clamp completing the circuit. Whether or not I could have actually welded or not I'm not sure as I didn't try. The circuit breakers didn't trip out. I didn't die or even get a tingle so I just continued to weld for a while before calling it quits for the day.
The only explanation I can see is that the welder was somehow using the 240V electrical earth to complete the weld circuit and it could do it from both electrode and work clamp. The ground, as in dirt, gravel and rocks, is extremely wet due to several days of heavy rain but I just don't think this should happen and until I hear otherwise, I don't really like it.
Any thoughts or explanations would be greatly appreciated.
Read the full thread at metalworkforums.com...
Welding both ways.
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