georgehifi
2,768 posts 09-14-2017 10:39pm
Also look at the fact that you can buy mains earth cheater adaptor plugs, which give you the option to float the earth of that piece of equipment they are attached to from most hi-end audio stores, for doing exactly what I said before, to have one only earth point in the system as not to create a loop with the mains they are plugged into. Also many pro equipment have earth float switches on them, as do some hi-end audio, even the John Curl designed Halo JC-1 monoblocks have this also to stop loop problems if they are in different power points.
http://www.parasound.com/product-images/jc1_rear.jpg
It may be called a ground cheater but that is/was not its’ intended design an Listed use.
The reason for the 3 wire to 2 wire adapter is to connect an appliance or piece of equipment to a grounded 120Vac power system where the 2 wire branch circuit, hot and neutral conductors, were installed in a metallic raceway, conduit, and metal box. The pigtail or ground strap tab on the adapter was to be connected to the center 6/32 trim screw, that supports the cover plate to the 2 wire duplex receptacle. (Note the female 6/32 threaded hub is mechanically, electrically, connected to the supporting back strap of the 2 wire duplex receptacle.) Ground conductivity/continuity from the duplex receptacle metal back strap to the metal box was as good as could be expected back in those days.
So bottom line they were not designed to lift the ground. Though in many cases that is what they ended up being used for.
georgehifi said:
"Also many pro equipment have earth float switches on them, as do some hi-end audio, even the John Curl designed Halo JC-1 monoblocks have this also to stop loop problems if they are in different power points."
http://www.parasound.com/product-images/jc1_rear.jpg I would bet John Curl does not lift the safety equipment ground from the chassis of any piece of audio equipment he designs. I would bet the ground lift switch seen on the back of the amp lifts the signal ground from the chassis.
Jim