Why isn't my new Varimat V2 working??!!

I was called to the roof of a 5000 square TPO job recently where the contractor had called frantically, saying he couldn’t get his brand new Leister Varimat V2 to power on. Before I got there, we went over a quick checklist to try and eliminate problems.

Do you have the right generator (click here for more info on selecting the right generator)
Do you have the right extension cord and plugs (to fit your generator)
Are you getting power at the end of the extension cord
Is the plug installed correctly on the Varimat cord
Is all your equipment free of visible signs of wear and/or damage
Are you separating load types

The answer from the roof was “yes” to all these questions, so I headed out. Once on the roof, the picture started coming together. I reworked the list, starting last to first. The Leister Varimat V2 and Triac S handgun are both linear loads. You shouldn’t run non-linear loads (on/off equipment) such as screw guns, radios or Saws-Allz when working with linear loads (the Leister equipment).

The Varimat, plugs and extensions cords looked brand new. The generator also seemed to be relatively new. I took apart and inspected the Varimat’s plug, insuring that the wires were solidly connected. I then checked the extension cord, since the plug to the generator was an L14-30 (4 prong). We’re used to the L6-30 (3 prong) plug and socket, so this means that the L6-30 plug was switched for the L14-30 plug. Again, all wires appeared to be properly connected. At this point, I was scratching my head. To this point in my checklist, everything the contractor had said, was true. Maybe this V2 was the “exception to the rule” that all Leister products are built with superior technology and expertise. I ran through the checklist in my head again, and realized what I missed…power. He said he had power. I’d checked and re-checked everything else…time to pull out the volt meter and see for myself.

Results of testing ground/first hot socket

OK, good start. There is power. When I moved to the second hot socket, I got a big fat goose-egg.

So, we’re getting power, but only getting 120V off one of the two hot sockets. The V2 won’t power up with only 120V, it needs at least 200V to start up. Now it was time to move to the generator. I checked the output of the generator, and found 120V off one socket, 0V off a neutral socket, and 120V off the 3rd socket. So the generator was putting out 240V. This lead me to the extension cord’s plug.

I took apart the plug, and realized that someone had incorrectly wired the plug. The three wires were connected to the ground (correct), one hot (correct) and the neutral (incorrect). I re-wired from the neutral to the other hot and reassembled the extension cord. I tested power at the socket end of the extension cord, and got 240V. Plugged in the V2 and away we went!