Oh yes I have and I'll never forget it. I was installing a sub panel in a lighting showroom as a young and stupid apprentice. My boss said "watch out for that wild leg". My interpretation of that was the hot brunette salesperson who worked there. Anyway, I set a 100A fused disconnect, bugged it in (hot of course) in the trough, and ran my feeders to the new panel. Naturally, I ran LOTS of MWBCs with a common neutral to the ceiling tracks used to hang the display fixtures. Checked everything for shorts after hanging them up, went back to the disconnect, threw the handle and ***poof***. Bulbs were shattering, smoke was coming out of LV fixtures, you name it. Quite a show for sure.
Not only did I have to change out the sub panel to single phase (all done with EMT of course), but had to pull additional neutrals for just about every set of MWBCs. I was NOT happy, nor was the customer, nor was my boss.
Life's lesson #1: The term "wild leg" has nothing to do with attractive women!
