Electrical installations and equipment may only be operated in proper condition and have to be preserved in said condition. Therefore, they have to be verified for proper condition by an electrician or under the instructions and supervision of an electrician.
Electrical installations must be verified:
before initial commissioning according to standard HD 60364-6:2007 "Low-voltage electrical installations – Part 6: Verification" (June 2008, German adoption of HD 60364-6:2007),
after modifications or repairs, before recommissioning, according to the same standard;
and at certain intervals according to EN 50110-1: 2013 "Operation of electrical installations, Part 1: general provisions" and further national regulations if applicable.
Electrical equipment must be tested according to national laws and standards.
One part of the verification of electrical installations is the measurement of the insulation resistance. In installations with a nominal voltage up to 500 volts AC, a test is performed with 500 volts DC. The insulation resistance must not be lower than 0.5 megaohms (MΩ). Where the nominal voltage exceeds 500 volts, the direct-current voltage for measurement is 1,000 volts and the insulation resistance must be at least 1.0 MΩ.
Measuring instruments must comply with the definitions of
the series of standards DIN VDE 0413 "Equipment for testing, measuring or monitoring of protective measures",
the series of standards IEC 61557 and/or
the CENELEC series of standards EN 61557.
The insulation resistance measurement must be performed for the outer conductors and the neutral conductor to earth. To reduce measuring efforts, outer and neutral conductors may be connected to each other. For measurements with connected electronic equipment, e.g. ECG, this is even required.
Connected luminaires with parallel capacitors or radio interference suppression filters can lead to faulty measurements. Moreover, there is a risk for electronic components of the equipment to be damaged by the measuring voltage. TRILUX luminaires remain undamaged by insulation resistance measurements due to their circuit configuration. This applies for LED luminaires as well as luminaires intended for fluorescent lamps, with LLCG or ECG.