BS EN 61557-8. 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 8. Insulation monitoring devices for IT systems Electrical measuring instruments, Electrical protection equipment, Electrical safety, Safety devices, Low voltage, Low-voltage equipment, Electrical insulation, Computer networks, Data processing, Marking, Instructions for use, Type testing, Electrical testing, Electrical resistance, Resistance measurement, Impedance measurement, Electrical impedance, Response time, Rated voltage, Visual inspection (testing)