Electrical Installation & Full Fit-Out (3-Bedroom Flat)

The work comes in two stages. Plastering, skimming and painting usually happen in between.

First fix is the skeleton of the installation. The electrician marks out cable routes, cuts chases in the walls, lays the cables, fits back boxes for sockets and switches, and prepares connection points for lights and appliances. This covers the power side: sockets, lighting and supplies to the cooker or water heater. If agreed, it also covers low-voltage cabling such as data cables for internet and TV, a doorbell or an alarm.

Second fix is the part you see. Sockets, switches and faceplates go on, lights and appliances are connected, and the consumer unit is fitted with breakers, residual current protection (RCDs) and often a surge protection device. Every circuit is labelled.

The job finishes with inspection and testing. The installer, or a separate inspector depending on local rules, measures insulation resistance, checks protection against electric shock and tests the RCDs, then issues a certificate with the results. Without it the installation is not properly handed over, and insurers or buyers may ask for it later.

1. Plan the layout together: where the sockets, switches and lights go, plus the kitchen units, the TV wall, the beds and a desk. For a flat of this size a proper wiring plan pays off.
2. Remove the old wiring and mark out the new routes.
3. Cut the chases. They run horizontally or vertically in defined zones, never diagonally across a wall, so that nobody drills into a cable later.
4. Lay the cables, fit the back boxes and fill the chases with plaster or mortar.
5. Plastering, skimming and painting (done by other trades).
6. Second fix: sockets, switches, light fittings, appliance connections and the consumer unit.
7. Test every circuit, carry out the final inspection and hand over the paperwork.

Copper cable is standard. Lighting circuits usually use a 1.5 mm² cable and socket circuits 2.5 mm², while a cooker or hob gets its own circuit with a heavier cable, in some countries supplied on three phases. The electrician sets the exact cable size based on the load and the length of the run. Data cables are kept apart from power cables so the signal is not disturbed.

The technique is the same as in a smaller flat. What changes is the number of points, circuits and cable lengths. A 3-bedroom flat typically has a living room, three bedrooms, a kitchen, a bathroom and a hall, so there are more circuits to plan and longer runs from the consumer unit.

• Separate circuits for the oven, hob, dishwasher, washing machine and water heater, each with its own protection
• Enough socket circuits so that bedrooms, the living room and the kitchen are not all on one breaker
• Often a home office corner, which means extra sockets and a data point by the desk
• Preparation for air conditioning, even if it will only be fitted later
• Data cabling to the TV wall and possibly to bedrooms, since Wi-Fi does not always reach every corner of a larger flat
• A consumer unit with spare ways for future circuits

How much work is involved depends on several things:

• Wall type: chasing into concrete panels is slow, while brick is easier to cut but creates more dust
• New build or renovation: in a renovation the old wiring has to come out first and the walls need repairing
• Number of points and circuits: every extra socket, light or dedicated circuit adds labour and material
• Fittings: designer switches, dimmers, USB sockets or smart modules take longer to fit, and smart modules often need deeper back boxes
• State of the flat: an empty flat and a finished furniture plan save time
• Late changes: moving a socket after plastering means cutting into the wall again and making good

• Too few sockets, especially in the kitchen, at the TV wall, by the beds and at the desk. Extension leads then raise the risk of overloading
• Sockets hidden behind wardrobes or kitchen units because the furniture was not planned in time
• One circuit for the whole kitchen, so breakers trip during ordinary cooking
• A small consumer unit with no spare ways, leaving nowhere to add a breaker for a later air conditioner or tumble dryer
• Missing RCD protection, which guards against electric shock
• No wiring diagram and no test certificate

In practice it helps to lay empty conduits in ceilings and walls for things you do not plan yet. Cutting into finished walls later is far more disruptive.

This is a job for a qualified electrician who is registered or licensed under your local rules. It is not DIY work: a wiring fault can cause injury or fire, and your insurer may refuse to pay for the damage.

In a block of flats, talk to the building management or owners' association before work starts. The rising main, the meter and the main supply are not yours alone. Any change to the main fuse or supply capacity is arranged with the local network operator. If the renovation also includes building work, such as removing partition walls, check with your local building authority what approval is needed. Do not assume a simple notice is enough.

The installation is designed and built to your national wiring rules, which in most countries are based on the international IEC 60364 series for low-voltage installations. The test certificate is the proof that these rules were followed.

At handover, walk through the whole flat and check that:

• Sockets and switches sit at consistent heights, straight, firm and flush with the wall
• Every socket is live and every light works from the right switch
• Bathroom fittings have an IP rating suited to their zone
• The consumer unit has RCD protection and the test button trips it
• Every breaker has a clear label, for example "Kitchen sockets"
• There are spare ways in the consumer unit for future circuits
• You have received a wiring diagram and a test certificate with measured results
• You have photos of the walls with cables in place, taken before plastering