Workpiece Grounding

[henrym]

interesting. I guess all I really need to do is maintain a clean work connection and proper plugging as I have before.

thanks

[Gadget]

That should do it.

[woofer456]

I worked for years in the ship building trade and there was no concerns to the polarity of the welding machine, many times there would be machines running using different polarities on a metal ship sitting in water (earth ground). There were occasions when a piece of equipment, like a grinder would get fried but that was usually the result of an electrode touching the outer case of the tool.
In my own shop I have a grid in the floor that is connected to earth ground and to the ground clamp of the welding machines, and at times, I run one machine straight polarity (DCEN or DCSP) and the other reverse polarity (DCEP or DCRP) I have no problem.
I have the ground wire on the back of my LS 200P connected to earth ground as the instructions recommended.
I hope that this helps clear up the question.
Bob

[woofer456]

One other thing I should mention, if your work table or work piece is not ground to earth be careful as not to place yourself between the work piece and the tungsten or the tip of the plasma when the trigger is pulled, you could get a high frequency shock.
I recommend wearing shoes with rubber soles, to insolate you from earth ground, if the floor is wet you could get a shock there as well,

Bob

[KHK]

In this case expeence counts!!!

Thank you for your advice.

keith

[bhardy501]

When I was in welding school, years ago, we had meal welding booths seperating the machines. I was welding on over head plate using 7018s. I had leaned up against the wall and was going along good. My shirt had rode up a little and I had bare skin touching the wall. Well my rod stuck and when leaned up to pull it free my skin broke contact with the wall. I got zapped pretty good on my left side just above my belt. After a few colorful words, I made sure my shirt was down and continued on with my work. It will definitly get your attention.

[henrym]

I found more info on workpiece grounding:

http://www.lincolnelectric.ca/knowle...ing_safety.asp

http://www.aws.org/technical/facts/Z49.1-2005-all.pdf < ANSI stuff, pages 44-47


hmmmm. I still don't know what to do! the manual for my 520D suggests connecting the positive output terminal (normally work lead) to the ground lug at the back of the machine, and to a good ground connection if I remember correctly.

but nothing seems clear enough. why can't someone just provide a diagram for all welding related electrical connections!!!

so far, I think that the idea is to connect the workpiece and welder chassis to a ground connection capable of carrying the welding current...

[KHK]

This is a difficult subject, NEA says that you should have onlt one ground for an electrical circut. I think the confusion comes from one thing, that is that the welder's output has NO electrical connection to the incomming power. So if you ground the Positive or negative welder outputs it makes no difference because there is no electrical connection to the incomming power.

I had a buz box welder that had a transformer that allowed no isolation to the incomming power. This only happened under high humity conditions. I burned up a grinder power cable because of this.

Poor equipment aside.
Do to varations in equipment, incomming power, and work enviroment. It is not possible to evaluate all possibilities.

The normal power used in stick welding, plasma cutting only pose a problem to the opreator(electrical shock)
TIG welding causes High Frequency emitions. This can cause interference on raido and tv signals. I live in one of the flight paths for Ohara field. I had to take extra steps to kill the RF

[woofer456]

henrym,
One thing that might make it easier for you to understand your grounding dilemma is -----
‘The current that runs the machine and the current that the machine puts out are two different circuit and though they both use earth as a ground they are not to be confused with each other, and unless you connect the two together (foolishly) one will not affect the other.
Bob

[KHK]

woofer456, Execelent drawing, thanks for sharing