Consumer unit replacement: the regs explained

Replacing a consumer unit in a home is notifiable work under Building Regulations, must use a non-combustible (metal) enclosureunder BS 7671, and is certified with an EIC — not a Minor Works Certificate. It’s a job for a qualified electrician, not a DIY swap.

Why the board has to be metal

Since 2016 (Amendment 3 to the 17th Edition, carried into the 18th), Regulation 421.1.201 requires consumer units in domestic premises to have a non-combustible enclosure or be housed in one — in practice, a steel unit. The change followed fires that started at loose connections inside plastic boards. A plastic consumer unit isn’t automatically dangerous on an EICR, but a new one being fitted today must be metal.

Why it needs an EIC, not Minor Works

The consumer unit is the origin of the installation. Replacing it is work on every circuit’s protection at once, so it’s certified with a full Electrical Installation Certificate — design, construction and inspection-and-test — not a Minor Works Certificate, which only covers alterations that don’t extend to a new circuit.

It’s notifiable work

In England and Wales, a consumer unit replacement is notifiable under Part P of the Building Regulations. That means it must either be carried out by an electrician registered with a Competent Person Scheme (who self-certifies and notifies on your behalf) or notified to building control before the work starts. Either way you should receive a certificate and, in time, a Building Regulations compliance notice.

What a good CU change includes

A proper board change isn’t just swapping the box: it includes testing the existing circuits, confirming they’re safe to connect to the new board, providing the RCD/RCBO protection current standards require, and issuing the EIC. If any circuit isn’t fit to reconnect, a good electrician tells you before the board goes on — not after.