Electrical Installation and Rewiring in Porto and Greater Porto

What Goes Into a Complete Electrical Installation

A new installation is not just “running some cables”. It means deciding how many independent circuits the home will have and what goes on each one. A typical home needs, at the very least, separate circuits for lighting, general sockets, the kitchen, the washing machine and dishwasher, heating and outdoor areas, plus a dedicated circuit for an induction hob, air conditioning or car charging if you have them.

The reason is practical and you feel it in everyday life: when something fails, only that part of the house loses power. The fault is traced in minutes instead of by trial and error with every light out, and you don't lose the contents of the freezer because the bathroom light tripped.

The second decision is the cable cross-section, and that cannot be put right later without opening up the walls. Lighting at 1.5 mm², sockets at 2.5 mm², kitchen and appliances at 4 or 6 mm² depending on the load and the distance from the consumer unit. Cutting corners here is behind most installations that start running hot after a few years.

Old Buildings in Porto: What We Actually Find

When we refurbish properties in the Baixa (the historic centre), in Foz or in Matosinhos, the same three things turn up every time. The first is wiring with no earth conductor: in houses built before the 1980s the sockets often have only two wires, which leaves the RCD unable to protect you the way it should.

The second is aluminium cable, used during certain periods because it was cheaper than copper. Aluminium expands and contracts more, and after decades the connections in consumer units and junction boxes work loose and overheat. When we find it, our advice is to replace it, not patch it.

The third is blocked or missing conduit: cable buried straight in the wall with plaster on top. There is no way to pull new cable through without opening the wall, and that completely changes the cost of a renovation. That is why a site visit is essential before we give a price. What we find in the walls decides the job.

Rewiring: When It Pays to Start From Scratch

Not every old house needs a new installation. The deciding question is simple: does the installation have an earth conductor and copper cabling in good condition? If it does, it is often enough to replace the consumer unit, split the circuits and add the ones that are missing. If it doesn't, patching it up ends up costing more within two or three years than rewiring the whole property in one go.

A full rewire of a typical flat is done room by room and, if you are living in the property, it can be carried out in stages: first the kitchen and bathrooms, where the heaviest loads and the water are, then the bedrooms and living room. The new consumer unit goes in during the first stage, already sized for the finished job, so it doesn't have to be replaced twice.

If you are thinking of buying a property to renovate, check the state of the installation before you sign. An electrical checklist before buying a house in Porto tells you what to look for. And if the house has been disconnected for a long time, the rewire usually goes hand in hand with applying for a ficha eletrotécnica (the electrical installation form) to have the power switched back on. That application is made in Portuguese, and we can handle it for you.

Doing the Electrics and Telecoms in the Same Job

If the walls are going to be open anyway, that is the one moment when running data cabling costs next to nothing. Doing it later means opening them up again, and it is the most common complaint we hear from people who renovated three years ago and now want decent home-office connectivity in a back room.

The same goes for a door entry intercom or video intercom and for spare conduits. A well-placed empty conduit costs pennies during the works and solves a need that doesn't exist yet: car charging, a network point, a camera.

Take a look at our pages on ITED and telecoms cabling and on door entry intercoms and video intercoms: if you are in the middle of a renovation, it makes sense to decide all three at once rather than through three separate quotes.

Stages and Timescales, to Fit Around the Rest of the Build

The electrician comes onto site at two separate points, and that shapes everybody's schedule. First the first fix: cutting chases and fitting conduit and back boxes before the plastering. Then, once the walls are painted and the floors laid, the second fix: pulling the cable, fitting switches, sockets and the consumer unit, and testing.

Between those two stages the other trades have to do their building work. So a typical flat is not “five days straight”: it is two or three days of first fix, the time the plasterers and decorators need, and then another two or three days of second fix.

What usually causes delays is not the electrical work. It is reaching second fix without having decided where the light points go, where the kitchen sockets sit and where the television will be. We ask for those decisions in writing before first fix, precisely so that nobody pays for them twice.

How much does it cost to wire a flat?

It depends on the number of rooms, light points and sockets, and on whether it is a brand-new installation or a replacement of the existing one. In a renovated two- or three-bedroom flat (a T2 or T3 in Portuguese listings), a complete installation typically comes to between 2,500 and 5,000 euros including materials. We give a fixed quote once we have seen the floor plan and the property.

Do you do electrical installations as part of a renovation?

Yes, and that is where timing matters: the wiring has to go in before the walls are closed up and suspended ceilings are fitted. If you call us early, we avoid unnecessary chasing and coordinate with the other trades.

Will the installation be certified?

Yes. A new or replaced low-voltage installation has to be documented and comply with the technical rules in force, and this is required for any new electricity supply contract.

How long does it take?

In a typical flat, the electrical work generally takes between three days and two weeks, depending on the size and on coordination with the rest of the building work.

Can the installation be done in stages to suit my budget?

It can, and that is common. What cannot be split is the first fix: chases and conduits are done in one go, because opening walls twice costs more than it saves. The finishing, meaning switches, sockets, lighting and automation, can be left for a second stage without any drawback.

Do I have to move out while the work is done?

For a partial renovation, usually not: we work zone by zone and keep power on in the rest of the house. A complete installation involves some days with the whole supply off, which we agree at the outset. If there is equipment that cannot be switched off, mention it during the visit and we will work out how to get around it.

Will a new installation be certified so it can be connected?

It will. A new installation or a significant renovation needs a technical form and certification before it can be connected under a new contract. We carry out the internal installation and deal with the paperwork it requires, which is all in Portuguese. See our electrical certification page for details.