Puts out lots of RF interference on cordless phones and radios in the shop, says the owner. Was told to ground the neg. side of the output of the welder (a TIG uses AC not DC to weld???---is this correct?) to a ground rod driven thru a hole drilled in the slab. Sound right? Sales person says not to hook it to my system ground which already grounds the chassis of the machine, but hook it directly to the "work" electrode.

i work in a fab shop and to alot of tig welding, you use DC for most metals and AC for aluminium and a few other non-ferrous metals. typically in DC mode it will use a high frequency to start the arc easier and in AC it uses a continuous high frequency, which you can set the Hz and balance of to improve the quality and cleaning of the weld. i have never heard of grounding the output of the welder but we have never had problems with our phones, 2way radios, or nextel when welding, i will ask our welding equipment company on monday if they have ever heard of this. hope it helps

rob

That doesn't make any sense to me. We go to extrordinary means to ground one side of a radio transmitter. I would think grounding one side of the welder would make it a more efficient antenna. I could be wrong though.
In real life I doubt you are going to stop the radiated RF from a welder. That was basically what Marconi's first radio transmitter was.

This is an aluminum fabricating shop, and the salesman told me that the high freq. travels on the outer skin of the leads (what that explains I'm not sure, and I don't think he understood the explanation he was simply trying to repeat). But He was adamant that tying the negative (or whatever the proper term is for that electrode) of the output side to a nearby non-system ground rod would clear up the problem. If I get to try it out next week I'll let you know. They weld nonstop all day, and the lack of ability to use the cordless phone is inconvenient to the other company employees (non-welders) in the shop.

I would think the interference is comeing form the arc it self, not the machine or the leads. you might try a cheaper cordless phone with lower band.

My cell picks up all kinds of interferance, and even produces some of its own - about every 2 minites I can here it send a data burst that gets picked up by my computer speakers or my car stereo. Truely annoying.