"PrecisionmachinisT" wrote:



what do they mean by door number 3?

Adding some sort of ground fault detection device...

IOW, a big ass GFI

A ground detection device does not need to be a GFi. Traditionally it
was a "3 light system" (usually done with neons). You wire the 3
bulbs in Wye, ground the center point, and connect one of the
remaining wires to each leg of the delta. When you get a ground on a
phase, that light goes out, or gets dim, and you know you have a
problem. Also provides a system ground reference that eliminates
"charge pumping".
jk