[mconstrain]

Alright, well now that we have our terms clear, I will say I am connecting the negative terminal on the plasma cutter to common on the motor. But regardless of terminology, that should theoretically work, correct?

And yes, my table is actually grounded (earth ground) all the time. Its connected at multiple points along the aluminum frame to be certain.

Oh and Jim.... I called Hypertherm about ordering a voltage divider and they said you don't actually sell them separately. Is that true? They did offer me one that comes as a replacement part for your PHC system, but it costs $195. That sounds a bit excessive for just a couple resistors and filtering elements so I think I will continue to try to make mine work.

Now that we have established that my table is grounded to earth ground and the negative terminal on the plasma cutter is only connected to common on the motor, is there any other suggestions you guys might have as to why the plasma cutter won't fire with it connected to common on the motor? Once or twice, it has actually produced an arc that way, but it sputters out within 3-5 seconds. Usually though, just a few sparks are emitted from the torch when you request it to fire while J16 is connected to common. Again, I appreciate everyone's help. Sorry if my terminology is not correct, but I don't feel I am a complete novice when it comes to electronics. The other 100+ I/O on this machine plus a CNC laser cutter, and CNC milling machine was wired solely by myself and works perfectly. This is the first circuit that seems to be kicking my butt and I can't figure out why. Is there any chance that a defect with the plasma cutter could be causing this or is it definitely something specific to the way I have this wired to the motor?