Grounding on Tice Powerblock

I guess no one knows the answer to this one....

Still no answer?

I had the same question when I got the Tice Powerblock 3 years ago. The answer to it might be that the other 2 receptacles were grounded through the holding skews. The receptacles Tice used is not an isolation type so the ground is connected to the center holding skew of each receptacles. Since the 3 receptacles were mounted on a metal plate, their ground were connected so one ground wire to one of the receptacles was enough.

Ground it....the Powerblock is a isolation transformer with a center shield. Grounding the Powerblock will increase the filtering of the transformer.