Here is a situation that we've never come across. We haven't really looked into it (as it will be a change order and it's part of a national rollout campaign)
We just installed circuits and outlets for Plasma, LCD and other TV's/Home Theatre Equipment. The entire time, my guys would get what seemed like bad static shocks when the touched building steel. Didn't seem like electrical shocks, but static. Didn't get any readings from the steel.
Finished the installed, turned everything on, and there were lines across the TV's. Told by the Project Manager that this has been happening at all the sites, it was usually a ground problem.
Tested the outlets, had 1.0V between ground and neutral at the outlet. Went back to the panel (these all came out of the same sub-panel) did not have any voltage between G-N. Now mind you, these are all homeruns.
Checked the rest of the store, had between 0.5V and 1.5V in the rest of the store.
A few important facts:
3PH 120V circuits.
Shared Neutral (3H, 1N, 1G)
The Ground was shared between 3 sets of wires (all in one conduit)
All boxes were grounded through the EMT and with ground screws.
All circuits 20A run with #10 THHN (no run longer than 120')
When the TV's are plugged in with a two-prong adapter (disconnecting it from the ground) it gets rid of the lines.
Apparently, there are engineers working on this as we speak. But has anyone ever come across this?
BTW- this store sells Home Theatre systems. These TV's and components will be installed in homes with questionable electrical systems. How unhappy will people be when their $3000 TV doesn't work right in their 40 yr old house?
