Buddy of mine runs a nice automotive shop and a month or so ago, he calls and says his Tig welder died (ancient Miller 300 rebadged as AIRCO) and could I check it? Since he does a lot of A/C adapters and so forth, I loaded up one of my spare TIG machines on the trailer and took it along. We trade machining and electrical work for mechanic work...so we really work at keeping each other happy..
Found a bad breaker..really marginal wiring...old shop, poorly wired in the first place. Since he had a couple hot jobs, I disconnected his old welder and installed my Airco 250 Squarewave (Esab) and showed him what does what...and turned him loose. He loved it and has been using it daily.
His hired help (who Ill refer to as "nose picker" on the other hand...liked the old Miller and decided on his own, to hook it back up......chuckle
SOW cord, 8/3..with red/white/green conductors. 240vt 1ph welder.
My buddy says there was a really bright flash..and all the power goes out in the shop..and he runs out to find the shaken nose picker standing there in the dark..with bits of smoke wafting in the breeze...
So he calls me up and asks me to come over and check everything out. They pulled the entire breaker out of the panel to make sure its safe...lol
I get there..and find the green and red wires attached to the breaker. which made a .nice Christmasy effect..but not exactly as intended by the maker or Code.....with the white wire going to the neutral lug in the breaker box..just like all the white wires in the 110 breakers....chuckle
So I swap the wires around and turn on the breaker then try the welder...no fan. Check the fuses..all ok...hum...
Kinda cramped on the acess side of the welder..so I asked the nose picker to clean me some space and go off to pee.
As Im standing there, making splashy splashy...
Bright flash..all the lights go out...
The guy is standing there...with a stricken look on his face...and smoke wafting in the air....
Seems when he tried to move the big B bottle of argon, he hit the side of the welder and the muffler tube rack...big melted spot on the rack....
WTF? Measured case of welder to ground..hot as hell. Shit..shorted transformer......hummmm...lesseee here..
Killed power, pulled the wireing access hatch...and found in years gone by, some dick head had hooked L1-L2 to green and white..with red to case ground.. And all the insulation was gone in the SOW cord between conductors as a result of the first miss hookup.
2 way hot right to the old case. The welder was on 2x4s, and we were all weaing rubber soles..so no one got bit when touching the case of the welder.Replaced the power cable (took it off my welder), wired both ends PROPERLY..and after chanting a mantra of supplication to Ready Kilowatt..(and checking for power from case to ground)...fired it up. Ran nicely,good arc.
Hard to kill a good old transformer machine. Gotta love em. Its gonna be good for another 30 years.
Gunner