Electrical installation work: cost of wiring per point 2026 and the process

Many flats and houses built before about 1990 still have their original wiring. In some countries this means aluminium conductors, which you can recognise by their silver colour when you take off a socket or switch cover. Elsewhere it may be old copper cable with brittle rubber or fabric insulation. Aluminium loosens and oxidises at the connections over time. The joint then carries current less well, so the terminals in sockets and switches heat up. If you see a discoloured or melted socket, your lights flicker or you notice a smell of burning plastic, the installation is giving you a clear warning.

Older wiring often has another problem: it has no separate earth conductor and no RCD (residual current device, a switch that cuts the power when current leaks where it should not). If the insulation inside an appliance fails, a socket like this will not reliably protect you from an electric shock. Old circuits were also never designed for the number of appliances people use today. You probably know the situation: you switch on the kettle, the microwave and the dishwasher in the kitchen at the same time, and the breaker trips.

A common response is to fit a higher-rated breaker in the consumer unit. That is a mistake. The breaker is there to protect the cable from overheating, so its rating has to match the cable size. A bigger breaker on an old circuit stops tripping, but the cables in the wall keep overheating, and that is far more dangerous. If a breaker trips often, the right answer is to spread the appliances across more circuits or to run a new cable.

A good electrical installation starts with how you will actually use each room. Before anyone cuts into the walls, walk through your home room by room and sketch where the furniture, appliances and lights will go. Put sockets where you can reach them. A socket behind a wardrobe or a bed is of little use.

• Kitchen: several double sockets above the worktop, dedicated outlets for the dishwasher, fridge, oven and cooker hood, and a dedicated high-current supply for the hob sized to its rated power, in many countries a three-phase connection.
• Living room and study: a group of sockets by the television and the desk, a data outlet and, if you need them, supplies for a projector or speakers.
• Bedroom: sockets and switches on both sides of the bed, so you can turn off the light without getting up.
• Bathroom and utility room: separate circuits for the washing machine, tumble dryer, water heater and heated towel rail.

Every high-power appliance should have its own circuit with its own breaker. Split the remaining sockets into several circuits by room. Then, if something fails or overloads in one room, the whole flat does not go dark. Ask for free space in the consumer unit for later additions. It also pays to lay empty conduits in the walls: flexible tubes through which a new cable can be pulled in a few years without breaking open the plaster.

Safe zones: where the cables run

Cables in walls should run only horizontally and vertically, in bands just below the ceiling, just above the floor and alongside corners, doors and windows. Never diagonally. Why does this matter so much? When everyone follows the rule, you know where a cable will not be, and you can drill safely without searching. In practice it often happens that someone runs a cable diagonally during a renovation to save a few metres, and years later another person drills straight into it while putting up a shelf.

The consumer unit, sometimes called the fuse box or distribution board, is the heart of the installation. Each circuit has a circuit breaker that protects it against overload and short circuit. An RCD, usually with a sensitivity of 30 mA, watches for something else: whether current is escaping outside the wires, for example through a person's body. If it is, the RCD disconnects the circuit in a fraction of a second. In a modern installation, RCDs protect all general socket circuits, the bathroom circuits and any outdoor sockets.

If one RCD covers too many circuits, a single fault switches off a large part of your home. That is why circuits are shared between several RCDs, or each circuit gets its own RCBO, a combined RCD and breaker in one device. Surge protection in the consumer unit is also worth having. It helps protect your electronics during thunderstorms and when the grid voltage spikes.

The rating of your main fuse and the supply capacity of your connection are set by the local electricity network operator. If you are switching to electric cooking, installing a heat pump or planning to charge an electric car at home, the supply often needs to be increased. You apply to the network operator, and they will usually ask for documentation from a qualified electrician.

Cables are laid in chases, narrow grooves that the electrician cuts with a wall chaser or chisels out by hand. Once the cable is in, the chase is filled with plaster. This work produces a lot of fine dust. A chaser with dust extraction should be used and the other rooms sealed off with plastic sheeting, otherwise you will be wiping dust for weeks.

In a block of flats built from prefabricated concrete panels, the concrete is hard and chasing is slow. Deep, long horizontal chases must not be cut into load-bearing panels because they weaken them. Before work starts, agree the extent of any work on load-bearing walls with the building management or owners' association and, if needed, a structural engineer. For anything that affects the structure, check with your local building authority what approval is required under local building regulations. Do not assume that a simple notification will be enough. In these blocks, cables are therefore more often run in the floor, behind plasterboard wall linings or above a suspended ceiling.

In a brick or block house, old wiring can sometimes be replaced without opening the walls, if it was originally laid in conduit. The new cable is simply pulled through the old tube. Most old wiring, however, is buried directly in the plaster, so a full rewire follows a completely new route.

In a bathroom, electrical equipment is placed according to protective zones around the bath and shower. The rule is simple: the closer to water, the stricter the requirements for protection and voltage. Ordinary sockets belong outside these zones, and in some countries they are not allowed in bathrooms at all apart from special shaver outlets, so check your local rules. Lights and extractor fans near the shower must be protected against splashing water. You will find this on the product as an IP rating with two digits, for example IP44. The higher the numbers, the better the protection against dust and water.

Outdoor sockets, garden lighting and a supply to a gate need enclosures rated for outdoor use and RCD protection. Cable buried in the ground is laid on a bed of sand with warning tape above it. When someone digs there later, the tape alerts them before the spade hits the cable. On long runs a larger cable size is chosen, so that the voltage does not drop too much at the far end.

A single light in the middle of the ceiling is no longer enough for a living room or bedroom. Good planning combines three kinds of light: general lighting, task lighting over the kitchen worktop and the table, and ambient lighting such as an LED strip or floor lamps plugged into a socket you control from a wall switch. Each group needs its own outlet and switch. That is why you plan the lights together with the sockets, before any chasing begins.

In a hallway, on a staircase and in a larger room with two doors, you will want to switch the light from more than one place. Two-way and intermediate switches do this, or push buttons connected to a latching relay in the consumer unit. If you plan to use dimmers, check that they suit your LED fittings. If they do not, the light will flicker or buzz.

Warm white light feels more comfortable in living areas. Neutral white works better at the bathroom mirror and in a study. Fittings built into a suspended ceiling or into furniture need space for their drivers and a way to reach them, so a driver can be replaced later without taking the ceiling apart.

Are you thinking about smart control of lights or blinds? Tell your electrician before the walls are chased. Many smart switches need a neutral conductor in the back box as well as the live, and a deeper box. In a new installation this is a minor detail; in a finished wall it is awkward to add.

A charger for an electric car needs its own circuit that can handle a continuous load, an RCD of the right type and often a three-phase supply. A solar PV system needs a place for the inverter, a connection to the consumer unit and approval from the network operator to connect to the grid. If you expect to add any of this in a few years, have a conduit or cable and space in the consumer unit prepared now. It saves cutting into finished walls later.

Work on fixed wiring may only be carried out by a qualified electrician, and in many countries the electrician must also be registered or the work must be notified to the authorities. Check what applies where you live. When a new or renovated installation is finished, it goes through initial verification, the first formal inspection and test. The electrician measures insulation resistance and loop impedance, checks that the RCDs work and that everything is connected correctly according to the applicable standards, usually based on the European and international wiring rules, and then issues an electrical installation certificate. The installation should not be put into use without it. If you cannot produce it after a fire or other insurance claim, your insurer may reduce the payout.

Keep the consumer unit circuit chart with the certificate, with each circuit described. Then, at every later alteration or fault, neither you nor the electrician has to work out which breaker belongs to which room.

As a non-professional, you must not work on the wiring or inside the consumer unit. You can, however, find out what is causing the tripping yourself, and that saves the electrician time. If you ever see smoke or flames, leave the room and call the local emergency number or 112.

1. Check what has tripped: the breaker for a single circuit, or an RCD, which switches off several circuits at once.
2. For a breaker, think about whether several high-power appliances were running on the same circuit at once. If so, move some of them to sockets in other rooms.
3. For an RCD, unplug every appliance on the circuits that went off and switch the RCD back on.
4. Plug the appliances back in one at a time. If the RCD trips after a particular one, that appliance probably has damaged insulation and should go for repair.
5. If the RCD trips even with nothing plugged in, especially after rain, the fault may be in an outdoor socket, a light fitting or the wiring itself. Call an electrician.
6. Press the test button marked T on each RCD every six months. The RCD must switch off immediately. If it does not, it is faulty and needs to be replaced by an electrician.
7. If a socket gets warm, smells or sparks, switch off its breaker straight away and do not use the socket until an electrician has checked it.

• You have received the electrical installation certificate and the consumer unit circuit chart with each circuit described
• Breakers and RCDs in the consumer unit are labelled by room and appliance
• All sockets, switches and light fittings work, and sockets are firmly fixed and straight
• Each RCD switches off when you press its test button
• You have photos of the wiring in the walls before plastering, with measured distances from corners and the floor
• There is free space in the consumer unit for future expansion, and any prepared conduits are marked on a plan