Voltage Indicator & Proving Unit Calibration

Surely Voltage indicator units are just GO or NO go devices. Or are you thinking of something more complicated? If the Voltage indicator is just a light or light and buzzer device than no calibration is required. It either works correctly or it does not. The same with proving units, they either work or not. Both devices can be easily tested for correct operation.


But, if the Voltage indicator has Voltage bands with rows of L.E.D.s showing Voltage ranges, as a rough indicator of Voltage present, like 12V, 24V, 150V, 250V, 400 V etc. then perhaps it should be tested for correct operation periodically. But in most cases the user, being familiar with its normal correct operation, would quickly notice if it was faulty in use. (We hope).


Z.

The proving unit proves the satisfactory condition of the voltage indicator, or at least that the lamps have not failed. As Zoomup has said, any malfunction would be obvious in use. I prefer the Drummond voltage indicator, which has 50, 120, 230 and 400 V lamps. What you really want to know is whether no lamps really means < 50 V so I can see the sense in checking the calibration at that level. I am not sure that the other levels are critical. After all, some voltage indicators go in steps of 50, 100, 200, 400 V. If you got 2 lamps when you expect 3, or 3 when you expect 4, I don't think that it would matter much and you could always check the voltage with your MFT, or even a suitable multimeter.

They generally test at 690 volts, that will light all the lamps in the voltage indicator, but I’d refrain from pushing the test leads of your installation testers into it.


You are testing it everytime you use it, assuming you are using it correctly, why would it need calibration?


 Andy