Consumer Unit Replacement Cost: When You Need a New Fuse Box

A consumer unit replacement in London usually costs £450 to £900 supplied and fitted. That is the headline. Where you land depends on how many circuits you have, the type of board, and whether the electrician finds anything that needs sorting once the old one comes off the wall. Let us unpack it, because this is one job where the cheapest quote is rarely the one you want.

How much does a consumer unit replacement cost?

Rough London pricing:

• Flat or small house, fewer circuits: £450 to £650
• Average three bed house: £550 to £800
• Larger home or higher spec board: £800 to £1,200

The main things that move the price are the number of circuits, whether you go for individual RCBOs on every circuit rather than a basic split load board, and whether a surge protection device is added. There is also the changeover itself. When the old board comes off, the wiring it was hiding sometimes needs minor remedial work before the new unit can be signed off safely. A decent electrician flags that on the day rather than quietly working around it.

Consumer unit or fuse box, what is the difference?

People use both words for the same thing, but they often mean different generations of kit. An old fuse box has rewireable fuses, a single main switch, and no modern shock protection. A modern consumer unit has circuit breakers and, crucially, RCD protection.

That RCD is the part that matters. As Electrical Safety First explains, an RCD is a life saving device that switches off the electricity automatically if there is a fault, protecting you from a fatal shock. An old board with no RCD simply does not do that. It is the single biggest reason to upgrade.

Signs you need a new consumer unit

• A board with old rewireable fuse wire instead of switches
• No RCD, often the case in boards more than 20 years old
• Breakers that trip constantly, which can point to a failing board or a circuit fault
• Any burning smell, scorching, or buzzing from the unit
• You are adding a big new load, like an EV charger or an extension

If you are getting repeated tripping or anything warm to the touch, treat it as urgent and get fault finding booked rather than living with it.

Do you always need a new one?

No, and any electrician who tells you that without looking is guessing. Sometimes the board is fine and the real issue is a single faulty circuit. A proper assessment tells you whether you need a full replacement or a smaller repair, which is the difference between a £600 job and a £120 one.

Frequently asked questions

How long does it take to replace a consumer unit?

Usually half a day to a day. Power is off for most of it, so plan around that.

Will I get a certificate?

Yes. A consumer unit change is notifiable work, and you get an Electrical Installation Certificate when it is done.

Is an old fuse box dangerous?

Not automatically, but without RCD protection it offers far less safety than a modern board, especially in kitchens, bathrooms and anywhere with water.

Get a fuse box quote

If your board looks like it belongs in a museum, or it keeps tripping, it is worth a proper look. See our consumer unit upgrades service or call 020 3653 2600 for a clear, fixed price.