How a renovation works

How to tell whether the whole electrical installation needs replacing

12 August 2026 · 2 min read

If your property predates 1985 and the electrics have not been touched since, they most likely need replacing entirely. The clear signs are: no earth connection in the sockets, a fuse board instead of circuit breakers, trips when two appliances run at once, or aluminium cabling or fabric-sheathed wiring. Rewiring a 90 m² property costs around €3,500–6,000.

Six signs it has fallen behind

The sockets have two holes and no earth contacts at the sides. Without an earth, a fault in an appliance can reach you.
The board has porcelain or screw-in fuses instead of circuit breakers.
The power trips when the oven and the hob run together, or when the air conditioning starts.
There is aluminium cabling (greyish and softer) instead of copper. It was used in some seventies builds and is now considered problematic.
Fabric-sheathed cables or cracked plastic insulation appear when a socket is opened.
The kitchen or bathroom has sockets with no residual current device, or none at all near the basin.

What rewiring includes

A new consumer unit with breakers, residual current devices and surge protection.
Independent circuits: lighting, sockets, kitchen, washing machine, bathroom and air conditioning kept separate.
New copper cabling sized for each circuit, with an earth throughout.
Chases, junction boxes and new sockets and switches.
The electrical certificate, issued by an authorised installer, which you will need if you ever increase your supply capacity or sell.

Cost and time

In a property of around 90 m², a full rewire costs €3,500–6,000 depending on the number of points and whether there is air conditioning. It takes four to seven working days, but it means chasing walls throughout the property: that is why it only makes economic sense within a renovation, when the walls are going to be opened anyway. Doing it separately, in a finished home, costs considerably more because the finishes have to be made good.

Can it be done in part?

It can, and sometimes that is the sensible route: rewiring only the kitchen and bathroom, which carry the heaviest loads, and leaving the rest. But be aware that a new board with old wiring behind it protects better without fixing the cabling. If the plan is to stay in the property for twenty years, doing it all at once is cheaper than doing it in two goes.