ECN Forum Forums General Topics of the Trade General Discussion Area Isolated Grounds Again!

Bob,
I believe the 6-32 plate mounting threads are electrically common to the mounting yoke. I will ring one out Monday to be sure and post back.

Nick you are 100% correct, after reading you post I grabbed one out of my truck, and yes the plate screw is connected to the yoke, so I will shut up about the metal plates.

As wrong as I was about the plate issue I still say it is easy for the IG to compromised in even with the most careful installation, by the end user.

If the prints call for IG I try my hardest to make that happen and it is a pet peeve when I see the building occupied and the IG end up jumped to equipment ground.

I totally agree. The end user is the weak link in the system. No matter how hard the owner tries there will always be someone plugging something in that will compromise the IG.

Just priced out 12/2 M/C IG cable. Unless in the spec sheets, I'll buy green tape.

Some links:
http://www.ecmweb.com/advsearchresults.asp?qry=isolated+ground&SiteID=13&MagazineID=31&CodeID=&selectSearch=mag%3B31

Just some food for thought. The most common corruptions of the IG are RS-232 cables used to inter-connect printers, modems, and CRT’s to your computer. RS-232 cables contain ground conductors and when your device is supplied by a different receptacle either standard or IG outlet, the whole IG system is compromised.

Another item that is over looked is IG should be dedicated. If there are multiple outlets on a branch circuit you defeat the purpose of an IG outlet. The only problem an IG circuit can prevent is common mode noise on the ground. And when IG’s are multiple you create common mode problems
One final point is do not waste money on installing an IG circuit in a residence. Best bet is to install a dedicated branch circuit. Reason is simple; in a residence a dedicated circuit is IG. Hence no conduit, plastic box mounted a wood frame member, and ran with NM.