If you’ve got an older plastic fuse box, you may have heard newer ones are metal — and wondered whether yours is now a problem. Here’s the straight story on plastic vs metal consumer units and what it means for you.

Why the change happened

Plastic (or more precisely, combustible) consumer units came under scrutiny after fires where loose connections inside the board ignited the plastic enclosure itself, letting the fire spread. In response, the wiring regulations changed.

Since 2016 (Amendment 3 to the 17th Edition, carried into the 18th), consumer units in domestic premises must be made of non-combustible material or enclosed in a non-combustible cabinet — in practice, this means metal (steel) boards. All new domestic installs use metal units.

Does my plastic unit need replacing right now?

Not automatically. The rule applies to new installations from 2016 — it wasn’t retrospective, so an existing plastic board isn’t illegal simply for being plastic. However:

• If the plastic unit is old, damaged, scorched, or lacks RCD protection, it should be replaced — and the replacement will be metal.
• If you’re having any work that involves changing the board, the new one must be metal.
• An EICR may flag an older plastic board, especially combined with other issues.

So: plastic isn’t an emergency on its own, but it’s often a sign the board is old enough to warrant an upgrade for other reasons (no RCDs, full, rewireable fuses).

Metal: the pros

• Non-combustible — contains a fault rather than feeding it
• Compliant with current standards
• Usually paired with modern RCD/RCBO protection when you upgrade
• More robust physically

“Should I upgrade just because mine’s plastic?”

If your plastic board is modern, RCD-protected, and in good condition, there’s no urgent need. If it’s old, full, lacks RCDs, or shows any heat damage, upgrading to a metal unit with full protection is well worth it — and you get the safety benefits of modern RCD/RCBO protection too. See our signs your fuse box needs replacing and RCD vs RCBO guide.

What an upgrade involves

Replacing a consumer unit means fitting the new metal board, connecting the circuits, and testing the installation — a competent electrician won’t put a new board on unsafe old wiring without telling you. It’s notifiable work, so it’s certified. See our fuse box replacement service.

The bottom line

• New install or board change? → It will be (and must be) metal.
• Old plastic board with no RCDs, scorching, or it’s full? → Upgrade to metal with modern protection.
• Modern plastic board in good condition with RCDs? → No urgent need; have it checked at your next EICR.

Not sure about your board?

If you’re unsure whether your consumer unit is due an upgrade, an inspection will tell you. GFL Electrical assess and replace consumer units across East London. See our fuse box replacement service or call 020 3774 5604.