RCD tests may be affected by loads downstream that contain electronic equipment or may incorporate permanent leakage current due to the capacitance of cables where circuit lengths are considerable. Someone carrying out inspection and testing on a ring-final circuit will not always see the same reading at each point during Step 3 of the ring-final circuit continuity test, unless the resistance (normally, the cross-sectional area and material) of the line conductor and circuit protective conductor (cpc) are roughly the same. Subsequent intervals will be recommended by the competent person carrying out the inspection and testing. However the guidance notes should not be contradicting the regs, especially when they are both produced by the IET. It is intended for all involved with specifying, designing, installing or verifying electrical installations and has been fully updated to BS 7671:2018:2022.

Calculations based on the (slightly higher) original value and then also rounded down might give the kind of result you observe? of BS 7671, supplied by a socket-outlet or pitch-outlet, which itself is required to be protected by an RCD with residual current rating not exceeding 30 mA by either Regulation 411. The Regulations apply to the design, erection and verification of electrical installations, also additions and alterations to existing installations. This list is not exhaustive as there are many smaller changes throughout the book not included here. of BS 7671 requires: “ Periodic inspection and testing shall be undertaken by a skilled person or persons, competent in such work”.The interval shall be determined dependant on the type of installation and equipment, its use and operation, the frequency and quality of maintenance and the external influences, to which it may be subjected. The IET Wiring Regulations is the national standard to which all domestic and industrial wiring must conform. Where required, periodic inspection and testing of every electrical installation shall be carried out in accordance with Regulations 651.

Installation test equipment should comply with the relevant BS EN 61557 standard, be in good condition and be formally calibrated. Regardless of RCD type, the test is carried out using an alternating test current, applied at the RCD’s rated residual operating current I Δn, the maximum disconnection time is expected to be less than 300ms for a general non-delay type RCD. The information in the report could be used to develop safety measures to mitigate the danger until remedial works can take place, such as isolation of an affected circuit.Table 51 has been modified slightly to take into account changes of colour identification for DC and abbreviations have been added. The observation should be a factual description of the problem, and not as commonly seen a proposal for the remedial works to rectify the issue.