In-service safety inspection and testing of electrical equipment

as aluminum foil) wrapped over the insulation.(2) Some hybrid constructions exist whereby a Class I item is totally encapsulated. By denyingaccess to earthed parts, a protective earth continuity test cannot be performed. In these casesonly an insulation test can be performed.G3 Protective earthingThe resistance to earth from protectively earthed parts in Class I equipment has to be low enoughto permit adequate fault current to flow to earth, thereby ensuring that the overcurrent protectiondevice in the final sub-circuit (that is, fixed wiring) opens quickly in the event of insulation failure.The protective earthing conductor also ensures that any leakage current from the live parts withinClass I equipment flows to earth via a low resistance path.G4 Insulation resistanceInsulation resistance testing is intended to confirm the integrity of the insulation between live mainsparts and accessible metal parts.Accordingly, equipment has its insulation resistance measured prior to commissioning, and atregular intervals during its service life to ensure that no degradation has occurred sincemanufacture, during transport, or over its service life.G5 Test equipmentThe equipment required to carry out the tests detailed in this Standard should be subject to routineverification at regular intervals to ensure it is working correctly and its accuracy is maintained.G6 DocumentationRecords of maintenance, including (but not limited to) tests, should be kept throughout the workinglife of the equipment. Such records are a useful management tool for reviewing the frequency ofinspection and test actions, and ensuring these actions have been carried out. It is recommendedthat such records be retained for not less than 7 years.Page 33