Does any one know how to meet the GFCI requirements of article 647.7(A)(1)? (Article 530 part G of â€™99) I did one of these installations a few years ago and this is what I found. Square D made us panel boards full of 20A 2P GFCI breakers. They were able to obtain a listing for the 60/120V application. However, upon energizing, the breakers would trip instantaneously on any piece of equipment that used a capacitive filter to ground. The fact was the breakers were doing their job. In the mass panic that ensued (being able to meet the on air date) what was discovered as a fix was replacing all the breakers with standard 2P non-gfci breakers and wiring a GFCI receptacle in each branch circuit. For some reason the GFCI receptacles were able to ride through the start up of these electronic pieces of equipment. The installation was accepted by the AHJ and has been working perfectly for over two years.
My concern is this. Standard GFCI receptacles are not tested and listed for use on 60/120V systems. I recently confirmed this via e-mail with Hubbell. I have yet to get a response from other manufacturers. There is a possibility I may do another installation just like the one mentioned this summer on a design build biases. I am researching now how to meet both the NEC requirements and manufacturer listing requirements for this system. Any thoughts or input would be appreciated.
Side bar: For anyone unfamiliar with this article the 60/120V system is derived from a special transformer. Each leg (1ph) is 60V to ground and 120V phase to phase. There is no neutral conductor. It is for noise reduction in sensitive equipment and its application is restricted to specific occupancies. (The â€™02 code has loosened up the occupancy restrictions considerably.)
I am posting this on IAEI, ECN and Mike Holt to get the widest range of responses I can.