Picked up three mag starters at a garage sale today. I tested them and they
do 'hold'. Problem is that they are not three phase.

Would there be any danger if I installed them (grinder) and hooked up only 2
of the 3 phase legs to the starter. The third leg I could hook up to a
manual switch. Just trying to save some money. Anybody see a safety
downside?

Thanks,
Ivan Vegvary