Electrical Fault Finding and Repair in Porto and Greater Porto

What to Check Before You Call Us

If part of the house has lost power, go to the consumer unit (the quadro eléctrico, or fuse box) and see which breaker is down. If it's only one, the problem is confined to that circuit, usually the sockets in one room or the lighting in one area. Unplug whatever is connected to that circuit and try resetting it. If it holds, the fault was in an appliance; if it trips again immediately, there's a fault in the wiring and there's no point in trying again.

If what tripped was the RCD (the larger switch, often with a test button, called the diferencial in Portugal), current is leaking to earth. That's the protection doing its job, not a fault in the RCD itself. The most common cause is damp in a junction box, an electric water heater or an outdoor socket, and in flats along the seafront in Matosinhos and Leça, with salt in the air, we see this regularly.

If the whole house has gone dark and so have the neighbours, the problem is on the grid and E-Redes (the grid operator) is responsible for fixing it. It's worth checking before calling an electrician: it saves you paying for a visit that wouldn't solve anything.

The Faults We See Most Often in Greater Porto

A breaker that trips at the same time every day is usually the water heater or the tumble dryer switching on while the circuit is already close to its limit. An RCD that trips when it rains points to water getting into outdoor lighting, roller-shutter boxes or balcony sockets. Sockets that get warm or discoloured around the edges indicate a loose connection, and that's one of the few situations you shouldn't put off, because this is how electrical fires start.

Lights that dip when you switch on a large appliance suggest undersized cable or a poor connection in the consumer unit. In a lot of housing built between the 1970s and the 1990s in Porto, Maia and Gondomar, we still find installations with no earth conductor on some of the circuits, which makes it impossible to protect those points properly without more substantial work. The symptoms that mean you should call a technician straight away, without waiting, are gathered in our guide to the 7 signs of a serious electrical fault.

A burning smell near the consumer unit or a socket is the one case where we ask you to switch off the main breaker and call us immediately, whatever the hour.

How We Tackle a Fault

We start by isolating the affected circuit and taking measurements, rather than swapping components at random. An insulation resistance test and a measurement of the leakage current tell us within minutes whether the fault lies in the fixed wiring, in an appliance plugged into it, or in the consumer unit itself. Replacing an RCD that keeps tripping without looking for the leak only treats the symptom, and you're back to the same problem a fortnight later.

Once we've found the fault, we explain what we've found and what the repair will cost before we touch anything. With most domestic faults, the repair is completed on that same visit.

When a fault reveals an installation at the end of its life, with no RCD in the consumer unit, circuits without earth or deteriorated wiring, we say so plainly and set out what would be needed. The decision is always yours: repair the point that failed today, or take the opportunity to bring the whole installation up to standard.

If you're renting, work on the fixed installation is normally something to agree with your landlord before it goes ahead. Because we explain what we've found and what the repair costs before touching anything, you have what you need to pass on to your landlord or letting agency, and we're happy to go over it again with them.

Why an Intermittent Fault Is the Most Expensive One to Ignore

Faults that come and go, such as a light that only flickers now and then, a breaker that trips once a week or a socket that works depending on the day, are the ones people put off most. And they're precisely the ones that most often point to a loose connection heating up inside a box or a consumer unit.

A loose connection creates resistance, resistance creates heat, heat degrades the insulation, and degraded insulation makes the connection worse. It's a self-reinforcing cycle and, unlike a short circuit, it doesn't trip anything until it's too late. That's why a thermal imaging inspection, or simply tightening and checking connections, fixes more long-standing faults than replacing components does.

The rule of thumb: if an electrical symptom is intermittent with no obvious cause, don't wait for it to go away on its own. It won't, and the cost of fixing it rises the longer it's been left to heat up.

How much does it cost for you to come out and find a fault?

The call-out and diagnosis have a fixed price, which we tell you on the phone before setting off and which is deducted from the repair if you go ahead with us. We never turn up without you knowing in advance what you'll pay for that first visit.

My RCD trips on its own every so often. Is that serious?

It's a sign of current leaking to earth and it should be investigated. Often it's damp in an outdoor circuit or a faulty appliance, but sometimes it's deteriorated insulation in the wiring, and that won't sort itself out.

Do you come out at weekends or at night?

Yes, for emergencies. Situations with an immediate risk, such as a burning smell, sparks, hot sockets or a total loss of power in the home, take priority.

Can you fix it the same day?

For most domestic faults, yes: we carry standard parts in the van. If a specific component has to be ordered, we leave the installation in a safe condition and come back as soon as it arrives.

The breaker always trips on the same circuit. What's causing it?

If it always trips on the same circuit and always with the same appliance plugged in, it's that appliance. If it trips on the same circuit with different appliances, it's the circuit, usually overloaded because extra demand has been added to a circuit designed for something else. Telling those two situations apart is the first step of the diagnosis and takes a few minutes.

The lights flicker when the washing machine starts. Is that serious?

A slight dip when a motor starts up is normal. An obvious, repeated flicker is not: it usually means the cable on that circuit is undersized or a loose connection is creating resistance. It's the kind of symptom worth having looked at before it heats up any further.

How long does it take to find a fault?

Most are found and fixed on the visit itself, within one to two hours. The ones that take longer are intermittent faults, because the symptom has to be reproduced. In those cases we tell you what we're doing and what it's costing as we go, rather than quietly running up the hours.

My flat is rented. Who should I talk to before the repair?

Faults in the fixed wiring are usually a matter for the landlord, so it's worth letting them or your letting agency know before work starts. We explain the fault and the cost of the repair before doing anything, so you can pass that on and decide together whether to go ahead.