RCD keeps tripping at home? Electrician in Seville, Spain to find the leakage

What it means when the RCD keeps tripping

The RCD (residual current device, called a GFCI or ground-fault breaker in the US, and diferencial in Spain) checks that all the current going into your installation comes back the same way. When part of it escapes to earth, through a faulty appliance, a bare cable or water in a box, it detects the difference and cuts the power in a fraction of a second. Homes in Spain use high-sensitivity 30 mA RCDs, because that current can already be dangerous for a person. That is why the Spanish Low Voltage Electrotechnical Regulation (ITC-BT-25) requires them on every circuit in a home.

So the RCD tripping is not the fault: it is the warning. The fault is the leakage, and it has to be found. If you have just moved to Seville and are used to a consumer unit with one RCD per row of breakers, the logic is exactly the same; only the names change.

Is it really the RCD? Check this first

Many foreign residents say “the trip switch keeps going” when in fact three different things can cut the power:

• The RCD (diferencial). It has a TEST button and its lever drops when current leaks to earth. This is the case this page is about.
• A circuit breaker (magnetotérmico, MCB). One lever drops on its own, usually the kitchen or the air conditioning, because of an overload or a short circuit.
• The power limiter (ICP) in the smart meter. Nothing moves in your fuse board, the whole home goes dark and the power comes back after a few seconds. That is not a fault but your contracted power (potencia contratada) being exceeded, and the solution is to spread your consumption or increase your contracted power.

If it is the RCD, read on.

Most common causes of an earth leakage

• A faulty appliance. Water heaters, washing machines, dishwashers and ovens are the first suspects, because they combine water and heating elements.
• Damp in the installation. Terrace or patio sockets, garden lights, junction boxes with water ingress or the motor of an awning or a roller blind.
• Damaged cables. A nail or a drill that has hit a conduit, cables chewed by rodents or old, dried-out insulation, typical of installations over 30 years old.
• Many small leakages added together. In homes with lots of electronic equipment (computers, TVs, chargers, inverter air conditioning), the tiny leakage of each appliance adds up and can trip a sensitive RCD.
• A defective RCD. Less frequent, but it happens with old devices or with ones that have suffered a power surge.

How we find the leakage

1. We isolate the circuits from the fuse board to find out which one has the problem.
2. We measure the insulation with an insulation resistance tester (megger), circuit by circuit, to know whether the leakage is in the cable or in an appliance.
3. We check the earthing, because without proper earthing (grounding) the RCD cannot protect you properly.
4. We test the RCD with a tester that measures its trip time and trip current.
5. We repair the faulty element and measure again to leave everything within the values set by the regulations.

When it is worth checking the whole installation

If the RCD trips frequently and the home is over 30 years old, the cause is usually the general ageing of the installation, not one specific appliance. We see it often in the 1960s and 1970s flats of Nervión, Los Remedios or La Macarena: cables with cracked insulation, no earthing and few circuits. In those cases the most cost-effective option is to rewire the apartment or, at least, to fit a new fuse board with several RCDs that share out the circuits, so that one leakage does not leave the whole home in the dark. You can read more about the typical buildings of Nervión and Los Remedios.

Typical leakages by type of home

Not every home fails in the same way, and knowing where to look shortens the diagnosis a lot:

• Flats from the 1960s to the 1980s. The usual culprit is ageing wiring: fabric or dried-out plastic insulation, junction boxes with joints wrapped in insulating tape and conduits that have collected damp for decades. Here the leakage is usually spread out and appears mainly in summer, with the air conditioning running flat out.
• New-build homes. In Sevilla Este, Palmas Altas or Entrenúcleos the wiring is new, so the leakage almost always comes from a newly installed appliance or a badly connected fitting during the move, such as a light hung without the terminals properly covered.
• Villas and townhouses in the Aljarafe. Outdoor damp is the main factor: buried garden lights, the pool pump, automatic irrigation or a barbecue socket without the right IP rating. See our page on the Aljarafe north.
• Shops and hospitality. Cold rooms, commercial dishwashers and fryers collect grease and damp, and an RCD that trips at peak time forces you to close. Here it is worth splitting the kitchen circuits across several RCDs.

Types of RCD and upgrades we can suggest

• Standard 30 mA RCD, type AC or A. This is what most fuse boards have. Type A also detects leakages with a pulsating DC component, common in inverter washing machines, induction hobs and electronic power supplies, and it is the recommended choice today.
• Super-immunised RCD. It keeps the 30 mA protection but withstands the surges and harmonics of modern electronics better, so it does not trip for no reason during a storm or when several appliances start at once. It is the solution when the RCD trips and no real leakage can be found.
• Automatic recloser. A small motor pushes the RCD back up when it has tripped because of a passing disturbance, after checking that there is no leakage. Very useful in second homes, houses with a fridge and freezer and businesses with cold rooms, especially if you spend part of the year away from Spain.
• Several RCDs in the fuse board. Splitting the circuits between two or three RCDs means a leakage on the terrace does not also switch off the fridge and the router. It is a cheap upgrade that avoids many emergency call-outs.

Guide prices in Seville

Before repairing we give you the fixed price of the specific job, and if the cause is an appliance we tell you so you can decide whether it is worth repairing. More rates on our prices page.

What you can do before calling us

1. Unplug the appliances in the area where the power went off.
2. Switch off all the circuit breakers in the fuse board and push the RCD up.
3. Switch the circuit breakers back on one by one. The one that trips the RCD is the affected circuit.
4. Leave that circuit off and use the rest of the home normally until we arrive.

If there is a burning smell, smoke or heat in a socket, do not run any tests: switch off the main switch and call our 24-hour emergency electrician. And if the RCD trips even with all the circuit breakers off, the leakage is before them, in the fuse board itself or in the cable that feeds it, and it must not be touched without a professional.