Description
Megger BM21 Insulation Tester Repair
The Megger BM21 is a high-voltage insulation resistance tester — a rugged 5 kV-class megohmmeter for testing cable, switchgear, and machine insulation, long used across utilities and industry. As HV test equipment, its faults concentrate in the high-voltage generator, the measurement circuitry, and the display.
June Company repairs and calibrates the Megger BM21 for utility and industrial maintenance crews.
Common Megger BM21 problems we fix
- Display issues — a blank, dim, or unreadable display, a common BM21 complaint, repaired.
- Won’t reach test voltage — HV generator degradation, repaired so it delivers full rated voltage.
- Readings drift or won’t settle — measurement-circuit drift, recalibrated against standards.
- Guard terminal faults — guard-circuit damage, repaired.
- Won’t power up or charge — power/battery faults.
FAQs
My BM21 display is failing — worth fixing? Yes. Display repair is routine, and we recalibrate the tester while it’s here so its HV output and readings are verified, with a NIST-traceable certificate.
Is the HV output verified? Yes — test voltage and insulation-resistance accuracy are checked against our standards.
Every repair includes NIST-traceable calibration and a 90-day parts-and-labor warranty. Email us or submit a service request.






