This base includes a built-in line fault isolator for use on Class A circuits. A detector must be installed for it to operate. The isolator base does not support the GSA-LED Remote LED.

The isolator operates as follows:

• a short on the line causes all isolators to open within 23 msec
• at 10 msec intervals, beginning on one side of the Class A circuit nearest the loop controller, the isolators close to provide the next isolator down the line with power
• when the isolator next to the short closes, it reopens within 10 msec.

The process repeats beginning on the other side of the loop controller.