Indication lights are an output devices (it does not measure), but is very important to us. These indication devices willhelp you to diagnose fault conditions or indicate ready to start, running or alarm conditions. There are a million indicationdevices out there. We haven’t tested them all, but we use some of the best from our suppliers. We have good track recordsand can advice you what to use. If the light is off that meant nothing, is it blown ? You do not know if it is still operational. There are ways around this. Call us and we canhelp.