On 8/26/2015 2:33 PM, Paul Koning wrote: > >> On Aug 26, 2015, at 3:16 PM, Jay Jaeger <cu...@charter.net> wrote: >> >> On 8/26/2015 8:19 AM, Paul Koning wrote: >>> >>> I heard of this sort of thing happening to the DEC building at Marlboro. >>> Supposedly it had two mains entrances, served from different power lines >>> (and different companies? Seems odd). One of the machine rooms had feeds >>> from both ends, and one particular system was fed from both. What happened >>> is that the "grounds" were offset enough, and with enough of a current >>> supply, that the ground strap that's supposed to connect the row of RP06 >>> drives melted. >>> >>> This sort of thing is a major electric code violation: you can certainly >>> have multiple services, but all the grounds are required to be connected by >>> substantial wire; you're not allowed to stick ground rods in at multiple >>> places and leave it at that. (The same goes for lightning rods.) >>> >>> paul >>> >> >> Quite possibly two different phases, and if so, the would be 90 degrees >> out of phase with each other. > > 90? Three phase power is 120 degrees apart, center-tapped "two phase" home > power is 180 degrees, but I don't know of any power company service that > produces 90 degree shifts. >
Yes, of course: 120 degrees. D'oh. > In any case, RP06s use three phase power. The issue wasn't the power in this > particular story, but rather the ground wire (the green "protective ground" > that isn't supposed to carry current at all under normal operation). > > paul > > I understand. Different shocks for different folks. ;) JRJ
