Do Portable welders like an 8-pack, or single large welding machines on trailers have to be grounded to earth with a GEC? We have a lot of them on the job and I am having trouble locating anything about a GEC. These are hardwired from a 220 and 480 VAC panels..transformer for 120/208 has no GEC to X/O bond from case of xfmr.
"Grounding" is not some mysterious voodoo. It's actually pretty straightforward - though I will credit illiterate engineers and code committees for making the topic as clear as mud.
Let's look at the types of situations when we think of "grounding." Where does the term come from?
Grounding. Ground. The earth beneath our feet is an obvious source. What's that got to do with anything?
Well, we NORMALLY want everything we touch to be at the same potential, lest current flow somewhere we don't want current to flow - like, say, through our bodies. So, we tie everything together, making sure that everything we touch is 'safe.' While often called 'grounding,' this is more correctly called 'bonding.'
Electricity, simply put, wants to 'go home,' wants to return to where it (the potential difference) was created. It will take all paths, in accordance with Ohm's law, greatly preferring an easy path to a hard one. Think about that for a moment.
Electricity is "created" at transformers, generators, and welders. We want the power to go out, do its' work, and come back - and the most effective way is to make sure there's only ONE path to follow.
In welding, this means one wire is placed near the work, and the other is firmly attached to the work. The idea is to make electricity jump the gap between, and melt the steel. We call the 'return' wire a 'ground,' but it's not. It's more like a 'negative' or a 'neutral.' Language fails me.
Since Ohm's law applies, we can touch the workpiece without fear, as the electricity will vastly prefer to 'go home' through that big fat wire, than to flow through us.
Now, what about 'ground rods?' The ONLY electricity that wants to return to the earth we stand on is electricity that came from there. We have two names for this 'natural' electricity: static electricity and lightning. That's the ONLY electricity that needs to 'return to earth.'
Hi, Thanks for the replies. I have an engineer on the job who is insiting that these welders have to have an external ground. They are fed with a 3 wire circuit..Two hots and a ground. The machine gets its ground from the source. The welders use their ground lead attached to the building steel or the work piece.
One engineer says he has the GEC and EGC in the same conduit feeding the main 480V panel..then from a breaker to that panel feeding a step down transformer..that does not have a GEC bonded to the X/O..which I have already confirmed that either building steel, water pipe or ground rod is required.
I am simply confirming that these 8 pack welders do NOT require a ground rod.