ECN Forum Forums General Topics of the Trade General Discussion Area Welding table, to ground or not to ground?

Norstarr, that doesn't make any sense unless the work clamp cable or terminal was connected to ground at some point before the clamp. That's the only way welding current could get to the shear then through the flat stock then to the work table.

Am I correct in assuming that the output of a welder is floating, neither terminal is connected to the frame or equipment ground at the welder?

-Hal

Our real goal is absolute operator safty and radiated RF to computer devices. i doubt if the situation described with the metal bridging the work table and other machinery will ever come up. This is a small prototype shop and is just not going to be that crowded.
The welding machine has a #6 ground back to the panel. I was thinking in terms of a Equipotential Plane as was discussed in a different thread concerning dairy barns on this system. Though originally discussed for a dairy barn would this concept be of any value in this sort of a situation?
Our current choices are bond the rebar system with attached grounding rods to the panel, the panel and work table or just the work table or to nothing. I would think one of these choices would make the most sense in opertor safety and electrical noise. From what we have seen most welders seem to tossed into an installation plugged in and if there is a problem the search for a fix starts. We are trying to do a class install and have no fix needed later as they are costly and time consuming at best, at worst other equiptment gets damaged or someone gets hurt.
Dave

As welding can be of various voltages, frequencies, ac or dc, and of any polarity- with these often being switchable settings on the machine- I do not think that the table should in any way be deliberately connected to the building's electrical system.
This is especially important as "power quality" issues become more important.

Experience has shown no need to go in the opposite direction; that is, isolating the table from the structure with insulators, etc.

At the heart of the welder is a transformer. This is a "separately derived" source. Any connection with the building's system should be through the transformer.

Ground rods are useful for voltage stabilisation for the power company, and lightning protection for you. Neither reason applies to welding.