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Clamping work lead to things like electrical conduit and sprinkler pipe

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  • Clamping work lead to things like electrical conduit and sprinkler pipe

    So as an electrician also, I'm a member of the Mike Holt forums. Recently a thread was started about weldors at buildings under construction using electrical conduit for their work clamps. There is general shock from the electricians about it, but as a weldor also, I'm trying to look at it more objectively. I don't know how well I am doing at trying to see both sides and ignore fake concerns and focus on real ones. If anything, maybe I'm bringing more thought to it.

    Anyway, the thread is here if any want to read it: http://forums.mikeholt.com/showthread.php?t=188133

    Even if you don't read it there (and you have to be an electrician to join and participate) I'd like to hear some thoughts about it. Is this a common practice? Are there obvious concerns? Is there no concern?

    Same thing about sprinkler pipe which was brought up. Any thoughts? I actually don't see a problem with it.

  • #2
    Sorry Mac I didn't read it, but I'll take a quick stab.
    For me it would certainly depend on how it was attached And what I was welding
    Are we discussing large structures?
    If the pipe in question is grounded to the weldment and their is a problem with current flowing thru it then the only way it becomes a problem is if the way it is attached cannot handle the amount of current. In the case of screws or bolts etc. Not to mention arc marks from low tension ground clamp springs. I've burnt stuff like that to a crisp.
    I wouldn't do it unless it was also welded to the structure. I wouldn't want welds on 1/2" steel to be filtered thru fastener connections of various metals, as apposed to a purposely attached ground lead. Unless we are discussing something altogether different.......then never mind

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    • #3
      Unless I'm welding to the conduit I can't see any reason to ground to it. As King said in a large structure the conduit won't be able to handle the amp's going thru it. Kinda like using 1/16 welding rod to ground a part next to your welding table. Looks like a light bulb filament before it falls to the ground.

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      • #4
        FK and OGD make all the right points. Might be some lazy weldors on this job. I generally try to ground close to what I'm welding on. Even when I'm doing a roll cage, I have the tendency to move the ground clamp at least to the side of the car I'm welding on. I can certainly see how the electricians on this job don't much appreciate this scenario.

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        • #5
          I'm appreciating the thoughts, but I wonder if you guys might be underestimating the ampacity of the pipe or metallic tubing. Fasteners would never take most of the current as they only keep the conduit in tight electrical contact to each other.

          Yes, clamping directly to building steel would be preferred, but the building in question is concrete and the weldors were using the conduit to go several floors up from their machines, so only needing to take up the stinger as their work was in electrical contact with the same supports as the conduit up top.

          The question was raised because one of the welders used a spiral-wrapped metal-clad cable as his connection, which we all thought was a bad idea, proven by it arcing against the EMT to get to the better conductor, and which I thought was just fine, and is what all the other weldors were using at the time.

          Last edited by MAC702; 11-29-2017, 09:57 AM.

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          • #6
            Must be too much work to drag the ground clamp up as well? I've never done that type of work, but I have done elevated work and I still drag the ground up with me so I can clamp close to my welding area.

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            • #7
              I'd be kicking them off the job for that, you never know when there might be a ground wire on a water pipe or the conduit, the ground wire might go through a combustible area inside a wall, the ground wire might be a 12 ga. wire and when 150 amps runs through a 12 ga wire, its going to be red hot and catch what ever its touching on fire.... this is a no brainer, the exact same thing can happen when connecting the ground to the beam.... always bring your ground with you and know the path of the electricity.

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              • #8
                The only time its acceptable to do what they are doing is in new construction and there are no wires and nothing that is combustible.

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                • #9
                  I would have been shown the door in a few shops I have worked in. Sorta like clamping on a car tailpipe to weld on the motor...Bob
                  Bob Wright

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                  • #10
                    Bottom line, unless one can visually see the conduit from end to end, It is an unknown. Never clamp to unknowns. Next, the conduit is not a part of what you are being paid to weld on. Never clamp to anything you aren't being paid weld on.

                    Yes I understand they are only using it as a piece of metallic conductor. At face value, simple enough, as a matter of policy, bad practice.

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                    • #11
                      Good comments, guys. I'm appreciating all of them. I'll let you know when I put them all together.

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                      • #12
                        Every one of those connections like the one at the bottom is a potential voltage drop.
                        Lazy. Unprofessional. Potentially hazardous. Stupid. Cheap.

                        www.facebook.com/outbackaluminumwelding
                        Miller Dynasty 700...OH YEA BABY!!
                        MM 350P...PULSE SPRAYIN' MONSTER
                        Miller Dynasty 280 with AC independent expansion card
                        Miller Dynasty 200 DX "Blue Lightning"

                        Miller Bobcat 225 NT (what I began my present Biz with!)
                        Miller 30-A Spoolgun
                        Miller WC-115-A
                        Miller Spectrum 300
                        Miller 225 Thunderbolt (my first machine bought new 1980)
                        Miller Digital Elite Titanium 9400

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