There seems to be some sort of phenomenon associated with arc-welders that escapes me.
This week , for the second time this year, i was called to a welder's shop that apparently caused a transformer fire. By this i mean the transformer on the utility pole.
The first time , i dismmissed this as a faulty t-former. This time i'm not so sure.
Both times, the service was small, 100 amp 120/240 residential, both times the welder was a rather large 50A unit. Both times, there appeared to be no other damage to panels, breakers, etc. Nothing tripped either...
I realize i lack any solid numbers here. Has anyone else dealt with this sort of scenario?
I'd be willing to bet that this was a cheap "buzz box" type welder. I've run into something similar. It didn't burn out the transformer but it did cause some overheating of the grounded conductor & grounding conductors at the service. The owner of a mobile home was welding some additional steel to the fromae under his mobile home & the welder was plugged into a properly installed 50 amp circuit. He was having a hard time running a bead & as stated, the neutral & grounding conductors were getting hot. The steel was bonded to the equipment ground of the mobile homes panel as required. All I could think of was some sort of bizarre circulating current. I've seen this problem again & it also involved welding to something that was bonded to the electrical service.
I never did come up with an answer.
Few things are harder to put up with than the annoyance of a good example.
as for this thread, the suspect is the return path's distortion. This is something i endevor to assess my next visit to a welding shop. maybe get my TRMS fluke on it while the welder does one of those "stuck the rod to the work" deals...
Old Appy: This is a pleasure to see your participation in this forum. I love New Zealand, and the people. I spent some time, in 1980 and 81, in Auckland, Wellington, and Christchurch. I was a member of the US Antarctic Research Expedition. The staging area was in Christchurch. I was really impressed by the work ethics, and quality performance by the New Zealand Team at Scott Base. They constructed a camp, using our packing crates, that was superior to our pre-fabricated camp that was shipped in the crates. Please continue to participate, you should have some good information to share. Best regards; Bennie
A few years ago, we experienced a severe cold snap. I remember reading a newspaper article about a homeowner using a welder to thaw out the house water pipes. Unfortunately, the house caught on fire. The insulation ignited because of excessive heat on the bonding jumper which was connected to water piping system. The heat was caused by extremely high current from the welder induced on the bonding jumper going back to the neutral in the service panel. The recommendation to avoid such a situation was to disconnect the bonding jumper before thawing out the pipes.