The devices in the JSC family provide a highly reliable means of determining whether voltage is present downstream of the disconnector or circuit-breaker knives when zeroing. They radically increase the safety of people assigned to maintenance tasks on electrical equipment. When voltage is present downstream of the disconnector blades, one or more LEDs on the JSC-88A will remain lit. The JSC's small size means it can be installed directly on the door of the disconnector, starter or control panel.

 

The JSC can also indicate a ground fault. If you have a ground fault on one phase, the LED for that phase will go out and the other 2 phases will be brighter.