Gordon Heaton
Titanium
- Joined
- Feb 19, 2007
- Location
- St. George, Utah
Had another senior moment this morning & forgot to attach the ground clamp to the welding table/workbench. My table is on casters, all steel and has multiple 120V outlets around the perimeter which are supplied with a 12ga cord from the shop wall outlets. The welds (aluminum @ 150A) were short with a cool down in the middle for grinding out the backside. Welding went fine, and it was only while coiling up the leads I realized I hadn't attached the ground clamp. Thought about it for a few seconds, and sure enough the supply cord to the wall was rather warm the entire length! The current return had been through the 12ga ground to the regular shop wiring.
The big issue here is that there is, of necessity, no protection on the ground circuit, and had the welding been of longer duration or higher amperage the resulting damage could have been extensive. The welder is an HTP Invertig 221H inverter. It had never occurred to me that this could happen and it requires a shop-circuit grounded connection to the welded piece, but that could be as simple as a metal drill or grinder plugged in and laying on the welding table. Has anyone else had this experience?
edit: thinking it through a bit more, I guess the damage would have all been exterior in my case, since all my wiring is in EMT conduit and that is bonded with a #4 wire to the foundation ground. Therefore only the cord from bench to outlet was at risk. For buildings with in-the-wall Romex, though, it could at least melt nearby conductors and at worst start a fire.
The big issue here is that there is, of necessity, no protection on the ground circuit, and had the welding been of longer duration or higher amperage the resulting damage could have been extensive. The welder is an HTP Invertig 221H inverter. It had never occurred to me that this could happen and it requires a shop-circuit grounded connection to the welded piece, but that could be as simple as a metal drill or grinder plugged in and laying on the welding table. Has anyone else had this experience?
edit: thinking it through a bit more, I guess the damage would have all been exterior in my case, since all my wiring is in EMT conduit and that is bonded with a #4 wire to the foundation ground. Therefore only the cord from bench to outlet was at risk. For buildings with in-the-wall Romex, though, it could at least melt nearby conductors and at worst start a fire.