IET Wiring Regulations

SOME PROPOSALS FOR AMENDMENT 2

Each new edition of the Wiring Regulations brings about improvements in safety standards for our electrical installations, and the recent draft for public comment on BS7671 IET Wiring Regulations (Sept 2020) is no exception. Here we look at some of the proposals from the draft document.

> PROTECTION AGAINST ELECTRIC SHOCK There will no longer be an option to use a risk assessment to justify omitting 30mA RCD protection on certain socket outlets (not exceeding 32A) in premises other than dwellings.

This means that all types of installations (commercial & industrial) will be treated the same as dwellings and all sockets (up to and including 32A ratings) will require protection by 30mA RCD. > UNWANTED TRIPPING OF RCDS Grouping several circuits together on one or two RCDs in a Dual RCD consumer unit may not meet the requirements of Amendment 2.

The use of RCBOs for each individual final circuit in domestic installations will be proposed as a specific means of avoiding unwanted tripping, because it keeps power flowing to healthy circuits. > DIVISION OF THE INSTALLATION The use of RCBOs is in addition to the existing requirements for subdividing final circuits which require unwanted tripping to be avoided. There are several existing regulations to consider: 314.1 - Division of the installation into individual circuits to avoid danger from unwanted tripping of RCDs. 531.3.2 – Avoiding tripping due to PE currents - this requires the designer to ensure that PE currents from connected equipment are no more than 9mA on any 30mA RCD.

Grouping several circuits together on one or two 30mA RCDs will not meet these regulations. > OVERVOLTAGE PROTECTION IN SINGLE UNIT DWELLINGS In single unit dwellings overvoltage protection will be required where the value of the loss of equipment and damage to the installation justifies the cost of the SPD.

> ELECTRICAL EQUIPMENT IS DEFINED AS… Any item for such purposes as generation, conversion, transmission, distribution or utilisation of electricity such as machines, transformers, apparatus, measuring instruments, protective devices, wiring systems, accessories, appliances & luminaires.