Mike, sorry you disagree.
Inside the room, all equipment is referenced to the room itself, there is no new safety risk introduced by the room being grounded differently. Outside the room, again, all equipment is referenced tightly to the room, so the operator does not see any differential. Should lightning strike the building, then true, the building earth potential may lift, but the operator is protected because he is referenced to the room which will not move much because the energy has been dissipated by the building earthing system. I state again this is for performance reasons, and is accepted practice. In a true Faraday shielded room, earthing the room is not even neccessary. Mind you, since these don't exist off the shelf, I'll stick to grounding using my original guidlines. NEC inspectors, when the rationale is explained to them have little problem. However, I have come across situations were the two unique earths were tied by a very heavy inductor.... Best regards, Derek N. Walton --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
