I am writing this regards to an article you had wrote about grounding/grounds. I do have some
questions in regards to said article.
First of all do you have any references to the way grounds should be connected?
Secondly you mentioned in your article that grounding to a structure should not be used if at all possible. My question in regards to this: If OSHA regulations state that it is okay to ground to structures why say no to this?
The reason I am asking is that where I am employed we use the building structure for grounding purposes and we have people who are getting shocked while welding. The material is 6061, using pulse Mig and GTAW. The machines are grounded to the structure and from said structure to said welding fixture using a jumper. In a nutshell I'm trying to find references whether they be OSHA or from some other agency in regards to grounding.
Any help or information would be greatly appreciated.
Thank you,
Chris A.
Chris,
Yours is the perfect example of how the terms "ground" and "work piece lead" get used interchangeably. This leads to a dangerous situation.
On a common welding power source you will find a + stud and a - stud. To one of these you would attach a conduit leading to the electrode (ie: a wire feeder, a stinger, a Tig torch). To the other you would connect a conduit leading to a Work Lead Clamp. The polarity required would determine if the work lead runs from the + or - stud.
First of all do you have any references to the way grounds should be connected?
Secondly you mentioned in your article that grounding to a structure should not be used if at all possible. My question in regards to this: If OSHA regulations state that it is okay to ground to structures why say no to this?
The reason I am asking is that where I am employed we use the building structure for grounding purposes and we have people who are getting shocked while welding. The material is 6061, using pulse Mig and GTAW. The machines are grounded to the structure and from said structure to said welding fixture using a jumper. In a nutshell I'm trying to find references whether they be OSHA or from some other agency in regards to grounding.
Any help or information would be greatly appreciated.
Thank you,
Chris A.
Chris,
Yours is the perfect example of how the terms "ground" and "work piece lead" get used interchangeably. This leads to a dangerous situation.
On a common welding power source you will find a + stud and a - stud. To one of these you would attach a conduit leading to the electrode (ie: a wire feeder, a stinger, a Tig torch). To the other you would connect a conduit leading to a Work Lead Clamp. The polarity required would determine if the work lead runs from the + or - stud.
OSHA will require that equipment be grounded to protect people from electric shock. The way equipment is grounded has nothing to do with the + or - stud on the front of the welding machine. This is accomplished through the permanent power connection supplying the machine (the plug). Or by a separate clamp and wire connecting the case or frame of the machine to ground (like the building). Sometimes both the plug and one of these wire connections is used. Again, they have nothing to do with the + or - stud on the machine.
ANSI Z49.1 - Safety in Welding and Cutting will require that the work table (positioner, fixture) also be grounded. This is accomplished with a conduit connected to the table or positioner, connecting it to a "driven rod" or often, the building. Again I clarify, this has nothing to with the + or - studs.
When we use the term "ground" we are talking about protection of people and equipment. You would be much better off referring to the leads coming off a welder as an electrode lead and a work lead, or a positive lead and a negative lead, but neither is ever considered a ground.
PWC
Paul W Cameron
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