Electrical service question

[John Coloccia]

FWIW, imagine what would happen if you ever lost the neutral in the sub-panel and it happened to be bonded to ground in the sub-panel. Your ground wire would suddenly become a current carrying conductor with a subsequent voltage drop all the way back to the service panel, and you would have stray currents energizing every ground connection on that panel, and you would never know it until it caused problems.

Even worse, if that cable were ever damaged, say by accidentally drilling through it...or a fire....or an earthquake....or anything like that, and you happened to loose the neutral AND the ground, you would then have a situation where the return path because the metal chassis of equipment. Every piece of metal in the shop suddenly becomes deadly, including the sub-panel itself. Keeping the ground and neutral separate insures this can never happen.