BS EN 61557-9. Electrical safety in low voltage distribution systems up to 1 000 v a.c. & 1 500 v d.c. Equipment for testing, measuring or monitoring of protective measures. Part 9. Equipment for insulation fault location in IT systems Electrical measuring instruments, Electrical protection equipment, Electrical safety, Safety devices, Low voltage, Low-voltage equipment, Electrical insulation, Electric power distribution, Computers, Computer networks, Computer hardware, Defects, Electrical faults, Accident prevention