Manufacturer recommends test and calibration every 12 months.

Non-Contact High Voltage Detector

Non-contact voltage detector
Wide range of detection; finds 80V to 275kV
One instrument fits all applications
Eight switch selectable ranges
Lightweight, minimizes swat at the end of the long hot sticks
Audible and visual indication of live voltage
Self-test position ensures that all system functions and indicators work properly by energizing complete system
#275HVD