To guard against IT room dangers, be aware of IT room characteristics before entering the room. We addressed two in our previous issue. Let’s take a look at three more.
Battery backup. It remains a shock hazard even if the service is shut down, so Art. 645 requires at least one battery disconnecting means inside the room and a wall-mounted one immediately outside the room.
Rampant grounding and bonding errors. Unlike other characteristics, this one is unnecessary. But these errors are both common and potentially lethal. Don’t assume “ground” means zero voltage. Test for a difference in potential between metal frames of equipment (“ground”) and communications cabling shields (also “ground”). If you find these, and you probably will, the solution is to bring the installation into conformance with the bonding requirements of Art. 250 and Art. 645.
Isolated ground receptacles. These have a distinctive orange coloring. There’s a high probability these will be installed incorrectly, violating both IEEE-142 (the Green Book) and basic electrical theory. They can pose a significant shock hazard.
