18th Edition Wiring Regulations Amendment 3 was released on 31st July 2024. In this article, we run through the key components of the wiring regulations, the updates in Amendment 3 and how you can stay up to date with the latest wiring regulations with City & Guilds Training – Electrical.

What are the Wiring Regulations (BS 7671)?

The Wiring Regulations, also known as BS 7671, are the national standard in the UK for electrical wiring. These regulations are essential for ensuring the safety and proper installation of electrical systems.

The Wiring Regulations set out the requirements for the design, installation, and verification of electrical installations. They cover everything from the types of cables and wiring methods to the safety measures that must be in place to protect against electric shock and fire.

Key Components of the Wiring Regulations

Design and Installation

The regulations provide detailed guidelines on how electrical systems should be designed and installed to ensure safety and efficiency. This includes specifications for wiring materials, circuit design, and protective devices.

Testing and Verification

After installation, electrical systems must be tested and verified to ensure they meet the required standards. This involves a series of inspections and tests to check for compliance with the regulations.

Safety Measures

The regulations include various safety measures to protect against electric shock, fire, and other hazards. This includes requirements for earthing and bonding, as well as the use of residual current devices (RCDs) to provide additional protection.

Updates and Amendments:

The Wiring Regulations are periodically updated to incorporate new technologies and practices.

Amendment 3 to the 18th Edition Wiring Regulations was published on 31 July 2024. This amendment, available as a free PDF download from the BSI or IET websites, serves as an add-on to the existing regulations, ensuring that professionals remain up-to-date with the latest safety and technical standards.

Key Changes in 18th Edition Wiring Regulations Amendment 3

This update emphasises the importance of selecting and installing protective devices, particularly when additional power sources like battery storage, EV charging equipment, or solar PV systems are involved.

A new regulation (530.3.201) has been introduced to address the use of bidirectional and unidirectional devices. It specifies that the selection and installation of protective equipment must consider whether a unidirectional or bidirectional device is appropriate. This change was necessary after it was found that some protective devices might be less effective in systems with bidirectional current flow.

The update also introduces two new definitions:

Bidirectional protective device

A protective device where it is intended by the manufacturer that a source of supply is connected to either or both sets of connection terminals.

Unidirectional protective device

A protective device where it is intended by the manufacturer that a source of supply is only connected to one defined set of connection terminals

Additionally, product standards for certain protective devices, such as RCCBs, RCBOs, circuit-breakers, and AFDDs, will now require markings to indicate if they are unidirectional, using labels like ‘in’ and ‘out,’ ‘line’ and ‘load,’ or arrows.

To stay up to date with the latest wiring regulations, check out our 18th Edition Wiring Regulations course.