Domakihub Install an RCD in Your Consumer Unit and Stay Safe
A step-by-step guide to adding residual current device protection to your Greek home, holiday rental, or hotel.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 5 min read
An RCD — residual current device — is one of the cheapest, most effective safety upgrades you can make to any building's electrical system. The video above walks through correct RCD wiring in detail; this article pairs those visuals with a practical step-by-step process tailored to Greek consumer units, where older boards often lack modern protection altogether. Whether you own a permanent home, a short-term rental on Airbnb, or a small hotel, getting an RCD fitted is no longer optional — it is increasingly required by the electrical inspection that underpins holiday rental licensing in Greece.
What an RCD Actually Does
A conventional circuit breaker protects the wiring: it trips when current exceeds the cable's rated capacity. An RCD does something different — it continuously compares the current flowing out through the live conductor with the current returning through the neutral. If those two values diverge by as little as 30 milliamps, the device cuts power in under 40 milliseconds, fast enough to prevent cardiac arrest from an electric shock.
Most Greek properties built before the early 2000s have MCB-only consumer units with no differential protection at all. Bathrooms, kitchens, and outdoor circuits are the highest-risk zones, because water and electricity share the same spaces.
RCDs and Greek Rental Inspections
Since the tightening of the short-term rental regulatory framework (the so-called Airbnb law updates administered through AADE and KEPA), properties seeking or renewing an E-class rental licence must present a valid electrical installation certificate — the Greek equivalent of an EICR. Inspecting engineers routinely flag the absence of RCD protection on wet-area circuits as a Category 1 or Category 2 defect, meaning the certificate is either withheld or issued with a short remediation deadline.
Adding an RCD to your consumer unit before the inspection is therefore both a safety measure and a commercial necessity. A single 40A/30mA RCCB covering bathroom, kitchen, and outdoor circuits typically costs under €40 in material and can be installed in a morning.
How to Install an RCD in Your Consumer Unit
- 1
Isolate the Supply and Verify It Is Dead
Inform your electricity provider or use the main isolator switch at the meter to cut supply to the board. Confirm the board is dead with a non-contact voltage tester on every busbar before touching anything. Greek meter cabinets are sealed, so the main isolator inside the consumer unit is your safe working point — never rely on switching off individual MCBs.
- 2
Map Your Existing Circuits and Choose the RCD Type
Photograph the existing wiring and label every MCB before you move anything. Decide whether you need a split-load board (one RCD protecting a sub-group of circuits) or a whole-board RCCB. For most Greek holiday rentals, a 40A/30mA RCCB placed upstream of the bathroom, kitchen, and external socket circuits is the minimum that satisfies inspection requirements. High-leakage loads such as dishwashers and washing machines may need a 100mA time-delayed type on a separate bank to avoid nuisance tripping.
- 3
Install the RCD in the Correct Physical Slot
RCDs are wider than standard MCBs — typically 2 DIN-rail modules. Slide the unit onto the rail and clip it firmly. Route the incoming live and neutral through the RCD's LINE terminals (marked L-IN and N-IN). The protected circuits' wires connect to the LOAD terminals on the downstream side. Watch the video above carefully here: a common mistake is connecting neutral conductors from different RCD zones together, which will cause the device to trip immediately and apparently randomly.
- 4
Connect the Earth and Check Polarity
Earth conductors bypass the RCD entirely and connect directly to the earth busbar — this is correct and by design. Before re-energising, use a continuity tester to verify that every downstream live terminal corresponds to the correct neutral and that no cross-connections exist between zones. In older Greek installations the neutral bar is sometimes shared across MCBs that now need to be separated; this is the step most often rushed and most often responsible for post-installation faults.
- 5
Test, Label, and Document for the Inspection File
Restore supply and press the TEST button on each RCD. The device must trip immediately; if it does not, cut power again and recheck all connections. Once the RCD trips and resets cleanly, test every downstream socket and light. Label the consumer unit door clearly showing which RCD covers which circuits. Print or photograph the completed schedule and retain it alongside the electrical certificate — inspectors in Greece increasingly ask for this documentation as part of the technical file for rental properties.
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FAQ
- Can I install an RCD myself, or does it have to be a licensed electrician in Greece?
- Greek law (Presidential Decree 108/2013) requires that any work on fixed electrical installations be carried out and certified by a licensed electrical contractor holding a valid professional licence from the relevant regional authority. A DIY installation will not produce a valid electrical certificate and could void your property insurance. Hire a licensed electrician, ask for a written quote itemising the RCD and any rewiring of the neutral bar, and obtain the signed certificate afterwards.
- Will an RCD trip every time I use a hairdryer or washing machine?
- A standard 30mA RCD will not trip from a healthy appliance in normal use. Nuisance tripping usually signals one of three things: a genuine earth leakage fault in one of the connected appliances, a damaged cable on that circuit, or too many high-leakage loads (dishwasher, washing machine, electric shower) sharing a single 30mA device. The solution is either to fix the faulty appliance or to split loads across two RCD zones, using a 100mA time-delayed type for the high-leakage circuits.
- How often should the RCD be tested in a holiday rental?
- Press the TEST button at the start of every rental season — or at minimum every six months. The button simulates a real fault and confirms the mechanism has not seized. Log the date and result in your property maintenance file. Greek rental inspectors and insurance assessors increasingly treat a blank maintenance log as evidence of neglect, so a simple dated note costs nothing and protects you significantly.