Domakihub How to Install a Two-Way Light Switch
Control one light from two locations — the right way, for Greek properties.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 5 min read
A two-way switching circuit lets you turn the same light on or off from either end of a staircase, corridor, or hallway — an upgrade that every multi-floor home, holiday rental, and hotel in Greece eventually needs. The video above walks through the electrical logic visually; the steps below translate that into a practical installation sequence you can follow with confidence. Whether you are retrofitting an older Greek property or wiring a new renovation, understanding the traveller-wire method once means you can replicate it anywhere.
Why Two-Way Switching Works the Way It Does
A standard single switch simply breaks the live conductor when you flip it. A two-way circuit is different: both switches are wired together by two conductors called traveller wires (sometimes called strappers), and each switch has three terminals — a Common (C), and two Alternates (L1 and L2). The live current always has a path through one traveller or the other, so flipping either switch changes which path is active and changes the light state.
This is why you cannot simply swap two standard single-pole switches and connect them with a single cable — the circuit needs that third terminal and the pair of travellers between the two switch boxes. Greek electrical regulations follow the European CENELEC standard, so the same terminal labelling and cable colours you see in the video above apply directly here.
Planning Before You Touch Any Wire
Before buying cable, sketch the run from your distribution board to the first switch position, from there to the second switch position, and finally from that second switch to the ceiling rose or light fitting. Measure each run carefully and add 20 percent for routing around door frames and cornices. In Greece you will typically work with NYM-J 3×1.5 mm² cable (grey sheath, three insulated cores plus earth) for the switch-to-switch traveller run, and standard 2×1.5 mm² cable for the feed and the final leg to the fitting.
Also confirm that your main circuit breaker for that ring is rated correctly and that the total load on the circuit — including the new fitting — does not exceed it. If you are in any doubt about the existing wiring condition, have a licensed Greek electrician (a Diploma Class A or B electrician under Greek law) inspect the board before you start.
Installing a Two-Way Switch Circuit in 5 Steps
- 1
Isolate the circuit and verify it is dead
Switch off the correct breaker at the distribution board and lock or tape it if other people are present. Use a non-contact voltage tester at the existing switch or ceiling rose before touching any conductor. In older Greek properties built before the 1990s the neutral and earth are sometimes swapped or absent — confirm each wire with a multimeter before proceeding.
- 2
Run the three-core traveller cable between the two switch positions
Feed NYM-J 3×1.5 mm² cable from the first switch back-box to the second. The three insulated cores (typically brown, black, and grey in modern cable) will become your two travellers and a conductor you will re-purpose as the switched live at one end. Route through wall chases or conduit and leave at least 150 mm of slack at each back-box. Label the cores at both ends with tape to avoid confusion later.
- 3
Connect the first switch (the supply end)
At the back-box nearest the distribution board, bring in your two-core feed cable (live and neutral) and the three-core traveller cable. Connect the incoming live to the Common (C) terminal of the first two-way switch. Connect the two traveller cores to the L1 and L2 terminals. Cap and insulate the neutral — it passes straight through this back-box to the ceiling rose and does not connect to the switch itself. Earth all metal back-boxes.
- 4
Connect the second switch (the far end)
At the second back-box, connect the matching traveller cores to L1 and L2 on the second two-way switch, mirroring the first — brown to L1, grey (or black) to L2, or whichever pair you labelled. The core you re-purposed as the switched live connects to the Common (C) terminal of this switch and then runs up to the live terminal at the ceiling rose. Again, earth the back-box and check that no bare copper is exposed outside a terminal.
- 5
Connect the ceiling rose, restore power, and test both switch positions
At the ceiling rose, terminate the switched live from the second switch, the neutral from the feed, and the earth. Fit the light fitting and lamp. Restore power at the breaker. Test by flipping each switch independently — the light should change state every time, regardless of the position of the other switch. If the light does not respond to one switch, the most common cause is a swapped L1/L2 pair on that switch; swap those two travellers and retest.
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FAQ
- Can I use ordinary two-core cable for the traveller run between the two switches?
- No. The traveller run requires three conductors (two travellers plus one switched live), so you need a three-core cable such as NYM-J 3×1.5 mm². Using two-core cable here is the most common wiring mistake and it will leave one terminal unconnected, making the circuit fail.
- My property is older and the existing cable colours do not match — what should I do?
- Many Greek properties built before 2004 use legacy colour conventions where red was live and black was neutral, rather than the modern brown/blue. Before connecting anything, use a multimeter to confirm which core is which. Re-mark every conductor with colour-coded sleeve tape at each termination point so the installation is safe for any electrician who works on it in future.
- Is this job legal to do yourself in Greece, or must a licensed electrician do it?
- Greek law (Presidential Decree 108/2013) requires that new electrical installations and significant modifications are certified by a licensed electrical contractor, who issues a Υπεύθυνη Δήλωση Εγκατάστασης (Electrical Installation Declaration). For a straightforward switch replacement in an existing circuit, many homeowners carry out the physical work themselves, but you should still have a licensed electrician sign off the declaration before notifying DEDDIE (the distribution network operator) of any changes.