Consumer Unit Upgrades: Does Your Fuse Board Need Replacing?

A consumer unit upgrade isn’t about ticking a box — it’s about whether your home has modern protection against electric shock and fire. If your fuse board still has rewireable fuses, a plastic casing, or no RCD, you’re relying on technology that’s decades behind what’s now considered safe. This guide explains what your consumer unit does, how to tell if yours needs replacing, what the rules actually say, and what an upgrade involves.

We’re Dorset Electrical Solutions, NAPIT-approved electricians based on the Ferndown Industrial Estate. Fuse board upgrades are one of the jobs we’re called out for most across Bournemouth, Poole, Wimborne, Christchurch and East Dorset — particularly in the region’s many older bungalows and post-war estates.

What a consumer unit actually does

Your consumer unit — the fuse board — is where the electricity supply enters your home and gets divided into circuits: lights, sockets, cooker, shower, and so on. Its job is to cut the power fast enough to prevent harm when something goes wrong. That’s it. It’s a safety device, not just a box of switches.

The critical question is how quickly, and how sensitively, it does that. An old rewireable fuse takes a relatively long time to blow, and it protects the cable — not you. A modern board with RCD protection detects the tiny current leak that happens when electricity finds a path through a person, and disconnects in milliseconds. That’s the difference between a shock and something far worse.

Signs your fuse board needs attention

• Rewireable fuses — the old ceramic holders with fuse wire you replace by hand. If you’ve ever wrapped wire round a fuse carrier, your board is obsolete.
• No RCD — no test button anywhere on the board. This is the big one.
• A plastic or wooden enclosure — since 2016, consumer units in homes must be in a non-combustible (metal) enclosure.
• Cast-iron or very old boards, or a mix of several boards bolted together as circuits were added over the years.
• Nuisance tripping — often a sign of an ageing board, a shared RCD, or a genuine fault worth finding.
• Signs of heat — scorching, browning, a smell of hot plastic. Call someone straight away, don’t wait.
• An EICR with C2s against the board — see our EICR guide.

What the regulations say

Two things worth knowing, without the jargon:

The enclosure must be non-combustible. Since January 2016, consumer units in domestic premises must be made of non-combustible material or enclosed in one — in practice, metal. That’s why you rarely see a new plastic board.

Replacing a consumer unit is notifiable work. Under Building Regulations Part P in England, swapping a consumer unit in a home has to be either carried out by an electrician registered with a competent person scheme (we’re NAPIT-registered), or notified to Building Control beforehand. Practically, that means it isn’t a DIY job or one for a general handyman — and when it’s done properly you should receive a certificate and notification, not just an invoice.

Current wiring regulations (BS 7671) also expect RCD protection on most circuits, and modern boards typically include surge protection. We’ll talk you through what your particular installation needs rather than selling you the biggest board on the shelf.

RCD or RCBO? The bit worth understanding

Older “dual RCD” boards split your home across two RCDs. It works — but if one circuit develops a fault, everything on that side of the board goes off. A fault in an outside socket can plunge half your house into darkness, including the freezer.

An RCBO board gives every circuit its own protection. If one circuit faults, only that circuit trips. Everything else stays on, and finding the problem is far quicker. It costs a bit more up front and it’s what we’d fit in our own homes. For most Dorset households — especially anyone with a home office, a freezer, or medical equipment — it’s the sensible choice.

What’s involved on the day

An upgrade is more than swapping a box. Done properly it means:

• Testing the existing circuits first. This matters. A new board with sensitive RCD protection will immediately reveal faults an old board tolerated — damp in an outside light, a borrowed neutral, deteriorated cable. Finding that before we start avoids nasty surprises.
• Checking the earthing and main bonding to gas and water, and upgrading if it’s inadequate. Very common in older properties.
• Arranging isolation — sometimes the supply cut-out fuse needs pulling, which involves your network operator.
• The changeover itself, then full testing of every circuit.
• Certification — an Electrical Installation Certificate and Part P notification.

Most domestic changeovers are a day’s work, with the power off for a good chunk of it. If the pre-testing throws up faults, we’ll tell you what we’ve found and what it’ll cost to put right before carrying on — never a surprise bill at the end.

What affects the cost

We won’t quote a number blind, because it genuinely depends: how many circuits you have, whether the earthing and bonding need upgrading, whether the board is going back in the same spot, whether it’s RCD or RCBO, and what the pre-testing uncovers. A straightforward swap in a two-bed bungalow and a rambling older house with thirty years of additions are different jobs.

What you’ll always get from us is a fixed price before we start. Tell us about your property and we’ll quote you properly.

When an upgrade gets triggered by something else

Often people don’t set out to replace a fuse board — it comes up because of something else:

• Getting an EV charger installed. A charger needs a suitable supply, spare capacity and sound earthing. An old board frequently isn’t up to it.
• An EICR that’s come back unsatisfactory.
• A rewire or extension, where the board is replaced as part of the works.
• Selling or letting, where a buyer’s survey or a tenant’s report flags it.

Frequently asked questions

Do I legally have to upgrade my consumer unit?

No. There’s no law forcing you to replace a working board in your own home. But if it’s unsafe — no RCD, damaged, overheating — it should be dealt with, and if you let the property an unsatisfactory EICR must be put right within 28 days.

How long does it take?

Typically a day for a normal home, with the power off for much of it. Bigger or more complicated installations take longer.

Can I fit one myself?

No. It’s notifiable work under Part P and needs proper testing and certification. It’s also one of the more dangerous jobs in a house — the supply side stays live.

Why did my new board start tripping when the old one never did?

Because the new one is doing its job. Modern RCDs detect faults an old fuse board simply ignored. It’s usually revealing a pre-existing problem — not creating one.

What’s the difference between a fuse box and a consumer unit?

They’re the same thing in everyday speech. “Fuse box” usually implies the older rewireable type; “consumer unit” is the modern term.

Do you cover my area?

We’re based in Ferndown and cover Bournemouth, Poole, Wimborne, Christchurch, Verwood, Ringwood, West Moors and across East Dorset.

Talk to us about your board

If you’re not sure what you’ve got, send us a photo of your fuse board — we can usually tell you a great deal from that alone, and we’ll give you a straight answer about whether it needs doing or not. We don’t sell upgrades people don’t need.

See our consumer unit upgrade service, or get in touch for a fixed quote.