Magswitch Magnetic Ground Clamp - 300 amp 8100746

There are a few rules when using it. You can't work close to it and overheat it (something like 172 degrees F max), or it will kill the magnet. You need to carry a cordless grinder to make sure you have bare metal all the time, and it can't be used over 50 percent duty cycle.

I had a job that I couldn't use a standard clamp all the time on large square tubing and this thing was the ticket to success. Just had to grind off the paint and then had nice solid grounds all the time and my welds improved because of it. It sort of forces you to have a good ground instead of just trying to scratch through the paint with your clamp and roll. Metal debris just falls right off when you turn the knob and release the magnet. I would still carry your regular clamp to the job in case you need to weld right next to it.