Re: Isolated Ground Circuit
Larry, as long as they are wired correctly, I wouldn?t make a stink either, they should be safe. On the other hand I am no fan of IGR. There only use is a possible means of obtaining common mode electrical noise reduction on the circuit it is used on. It is very easy to corrupt the circuit by interconnecting cables like RS-232, coax shields, or incidental contact with other grounded objects.
I work in the telecom sector and we do not use them period in any of our data-centers. We use strictly UPS and PDU?s with dedicated SG circuits. We will install them for customers who demand them, but they have to sign a waiver to exempt us from liability of corruption, which they usually do themselves.
Example they bolt their equipment in an equipment frame without isolation. The equipment frames are bonded to a SRG under the raised floor, or they interconnect at DS3 signal level via coax. I get a bang out of showing the customers they corrupted themselves when they raise a stink about it. They usually ask for assistance then, and I always advise SG. Problems seems to magically go away. They ask why, answer is the multi-point ground of the SRG system.
Now that is not to say they do not have any use. A/V systems can benefit is used properly with an isolation transformer. However if you use a isolation transformer with a dedicated quad outlet to power all the A/V equipment, then you do not need IGR b/c all equipment is served via SPG.
On the lighter side (cynical side) are the nuts in wood framed houses asking for IGR using Romex and plastic boxes.
[ December 02, 2004, 07:46 PM: Message edited by: dereckbc ]
