Circuit breaker keeps tripping: what it means

Safety first

It tripped for a reason. Before resetting it, look around.

• A burning smell, smoke, sparks, or a socket that is scorched or hot: do not reset, call an electrician. If there is a fire, get out and call 112, the European emergency number.
• Water near the fuse box, sockets or an appliance: touch nothing with wet hands or feet, and only switch off the main switch if you can reach it from somewhere dry.
• Never open the inside of the fuse box or the socket covers, and never tape or wedge a breaker so it cannot trip.
• If someone has had a shock and is still touching the appliance, switch off the main switch before you touch them, and call 112.

What each trip means

A fuse box in a Portuguese home, the quadro elétrico, usually has three kinds of switch: the main switch (geral), which cuts the whole flat; the RCD (diferencial), which detects current leaking; and a breaker for each circuit. Which one dropped says a lot about the cause.

A single circuit breaker trips

Usually too much load on that circuit: a heater, a kettle and a microwave running at once on the same sockets. If it trips with little switched on, or as soon as you reset it, there may be a short circuit in an appliance, a plug or the cable.

The RCD trips

The RCD drops when current leaks, often because of damp or a faulty appliance. Washing machines, ovens, older heaters and cylinders are usual suspects. If it trips every time the cylinder starts heating, see our guide on a hot water cylinder not heating. In a wet Porto winter it often coincides with rain getting into an outdoor socket, a balcony light or a junction box.

The whole flat goes dark

If the neighbours and the street are dark too, the fault is on the network, not in your home. If only your flat goes dark when the oven, the washing machine and a heater run together, your contracted power (potência contratada) may be too low for that use: spread the load or talk to your supplier. If it drops with little on, suspect a fault.

How to find what is causing it

With no burning smell or water in sight, you can run this test without tools, touching only the fuse box switches and plugs.

• Unplug the appliances on the circuit that tripped, or across the whole flat if it was the RCD.
• Reset the breaker or the RCD once.
• If it stays up, plug the appliances back in one at a time. The one that trips it is the suspect: leave it unplugged.
• If it trips with everything unplugged, switch off all the circuit breakers, reset the RCD and switch the circuits back on one by one. The circuit that trips it holds the fault.
• If it still trips, or a circuit breaker drops on its own with nothing plugged in, the problem is in the wiring. Stop there: resetting the board day after day hides the problem and heats the installation.

Old fuse boards

Many older buildings in Porto still have fuse boards instead of breakers. Never replace a blown fuse with wire or a stronger fuse: that lets a cable overheat until it catches fire. If fuses blow often, the board can be repaired and, where it makes sense, replaced with one that has breakers and an RCD.

When to call an electrician and how the job goes

Call an emergency electrician when the breaker trips with everything unplugged or keeps tripping with no explanation, when there is a burning smell or a hot socket, or when the RCD drops whenever it rains. Circuit breaker repair is rarely about the breaker: it is about the fault behind it. We carry out electrical repairs as an electrician in Porto and across Greater Porto, with a 24 hour electrical service. If the damp comes from a water leak, the job starts with a plumber in Porto, and we handle both on the same visit.

You call or send a message

A person answers. Tell us which switch drops, when, and what was on. A photo of the fuse box on WhatsApp, to +351 928 286 711, saves a lot of questions.

We agree the visit

On the phone we give you a realistic arrival time and agree how you would like to pay.

We trace the fault

The technician tests circuit by circuit with test equipment, and the suspect appliance on its own, to find whether the fault is in the appliance or the wiring.

You get the quote before we repair

We explain what we found and what it costs. If you rent, the quote is written so you can forward it to your landlord. Nothing goes ahead without your approval.

We repair and test

We repair and test with the appliances running, to confirm the board holds. If part of the flat has to stay off overnight, we say so plainly.

You keep the invoice

The invoice lists labour and materials separately. That document is your guarantee and what entitles you to complain if anything fails.

Circuit breaker questions