Tig welding without ground clamp connected

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I just finished welding a cap on some steel 11ga rectangle tube.  I was not using any filler.  I knew something wasn't quite right but I kept going anyway.  I had my xmt304 on lift arc.  After I finnished this piece I realized I didn't have the ground clamp connected to the table it was still hanging on the welder cart 5ft away.  How did that even work. Attached ImagesMiller XMT 304 cc/cvMiller 12RC w/ 15ft Tweco #4 GunMiller 30A SpoolgunCustom Thermal Arc TA 10/270 Generator "Thermal Star"Smith oxy/acet-propane with weld, cut & rosebud tipsAnd of course grinders, chop saws, hand tools
Reply:First guess is that you routed the welder to work ground through the building's electrical system's ground circut.Is the work table grounded?Does your cart have a 110/220 'power strip' on it?Be wary of The Numbers: Figures don't lie,. but liars can figure.Welders:2008 Lincoln 140 GMAW&FCAW2012 HF 165 'toy' GTAW&SMAW1970's Cobbled together O/A
Reply:I don't know who that could have worked.. You need to grind that steel clean before tig welding though!Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Originally Posted by mike837goFirst guess is that you routed the welder to work ground through the building's electrical system's ground circut.Is the work table grounded?Does your cart have a 110/220 'power strip' on it?
Reply:It found a ground somehow.  When I've made that same move with my HF tig, my HF went crazy with no tig arc.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:Originally Posted by osweld only the welder and the plasma are plugged into a heavy extension cord with 2 plugs on it.
Reply:Originally Posted by BistineauWas the plasma ground connected to the table? If so, then maybe it grounded through that at the extension cord connection back to the welder.
Reply:Grounded thru the buildings wiring ground. lol not good.Welding/Fab Pics: www.UtahWeld.com
Reply:What frequency? The electric found a path thru the building or possibly hi freqWhat freq ?
Reply:While you can't see how it grounded, IT DID.Not the first time that has happened. LOL
Reply:Sounds like you can save some dough by dispensing with your ground cables ... I wouldn't weld barefooted though!
Reply:After studying your pix, it looks like your work surface is connected to the lift arm via the square tubing off to the left in the first image.Unquestionably, the lift is well grounded. It is possible that the TIG or plasma cutter (my money is on the plasma) shares it work ground with building ground. So the circut was TIG through plasma to building to lift through other project to work table to clamped project. Not particularly efficient, but the job got delivered.Be wary of The Numbers: Figures don't lie,. but liars can figure.Welders:2008 Lincoln 140 GMAW&FCAW2012 HF 165 'toy' GTAW&SMAW1970's Cobbled together O/A
Reply:Center photo gives a graphic of the path.  Ground clamp is hanging by being inserted into the metal tube of your cable hanger bar.  The bar is bolted to the welder chassis.  The welder chassis is BONDED to the EQUIPMENT GROUNDING circuit (green conductors) which is then bonded to the ground circuit in the building electrical panel.  The GROUND circuits are BONDED to the panel ground which is bonded to the metal building structure AND the concrete slab the building is mounted to.Therefore, anything that is mounted on, or sitting on the concrete floor, becomes a GROUND POTENTIAL and only needs a VOLTAGE POTENTIAL to make an electric circuit.Reminded me of a story told to me our Airco products route man back in the '70s.A guy was welding in a shop that had a long steel welding table sitting on a concrete floor.  The weldor had finished a weld and hung his stinger (with a short stub of rod still in it) across the oxygen regulator on the torch cart parked near the welding table.The torch cart was "all steel" construction and was only sitting on the "damp" concrete floor.The stub of rod arced on the side of the oxygen cylinder.The guy grabs the stinger off of the regulator and walks over to the welder with it and turns off the welder.He then heads off to the shop office on the other side of the building.The oxygen cylinder then ruptures violently pretty much blowing out the sheet metal wall of the building nearest to the torch cart.An inspection/report of the ruptured cylinder by Airco and fire marshal described how the arcing on the cylinder caused it to rupture.As I recall, the report stated that the arc caused enough local stress in the cylinder wall that it cracked moments after the arc occurred.When the microscopic fissure breached the wall, that was enough for the high pressure inside the tank to simply forced the crack to open up all at once in uncontrolled expansion.Apparently Airco had distributed the story because our Airco guy had 2 pictures of the aftermath.  One showing a large gaping hole in the building where several panels of sheet metal were blown off, and the other of the ripped open oxygen cylinder.The cylinder did not "shrapnel" but it just looked like it had been sliced open lengthwise and then something like a "jaws of life" spreader had been used to spread it open.
Reply:Walkerweld,When I was taught about stick welding, the instructor made it quite clear that the stinger was hot as long as the welder was on. We were instructed to hold the stinger until the welder was OFF!That kind of simple saftey precaution prevents disaters like you just described every day.Let's keep our heads. Think about what we are doing. Being the path for HF starts is beyond unpleasant. Inadvertant not-welds have consequences. Remember to build the complete circut BEFORE you try to strike an arc. Only put the torch down when it is cold.Be wary of The Numbers: Figures don't lie,. but liars can figure.Welders:2008 Lincoln 140 GMAW&FCAW2012 HF 165 'toy' GTAW&SMAW1970's Cobbled together O/A