Domino Switch Diagram – Modular Plate Switch Wiring Explained
This is a free printable domino switch diagram: download the diagram as SVG or open it and print to paper or PDF.
A domino switch is a modular wall plate switch where individual switch modules clip into a common frame. This guide covers wiring configurations, connection methods, and safety requirements.
The term 'domino switch' describes a modular wiring accessory system where individual switch modules — each carrying one or more switching elements — clip or lock into a common face plate or grid frame. The result is a neat, recessed or surface-mounted switch plate that can combine multiple switch functions (lights, fans, sockets, dimmers, intermediate switches) in a single gang or multi-gang format.
The modular approach separates the electrical connection from the physical mounting. The switch mechanism module connects to the circuit wiring at the back, while the decorative face plate snaps on at the front independently. This allows the plate style and colour to be changed without disturbing the wiring.
Common configurations include:
- Single-gang single-switch: one module in one frame, switching one lighting circuit. - Multi-gang: two, three, or four modules in a wider frame, each independently switching its own circuit. - Two-way switching: a switch with two output terminals (common, L1, L2 or C, 1, 2) allowing a light to be controlled from two locations. Both switches in the two-way circuit are wired with a two-way switch module. - Intermediate switching: used between two two-way switches to allow three or more switching positions. The intermediate module has four terminals (L1, L2 crossing to L3, L4). - Dimmer module: replaces a standard switch module; requires a leading-edge or trailing-edge dimmer compatible with the lamp type.
Wiring conventions differ by country. In the UK (BS 7671), the switch wire from a junction box or ceiling rose is brought to the switch as a loop or radial spur. In many other countries, a permanent live, neutral, and switched live must all be available at the switch position.
Domino switch systems use push-in (fast-fit or back-stab) or screw terminals depending on the module design. Push-in terminals are suitable for solid or stranded conductors of the correct cross-section only — do not use push-in terminals with conductors outside their rated range.
All domestic switching work must comply with the applicable wiring regulations for the jurisdiction. In the UK this is BS 7671 (IET Wiring Regulations). In the USA, NEC/NFPA 70. In Australia and New Zealand, AS/NZS 3000. In most of Europe, IEC 60364. Only a qualified, licensed electrician should carry out fixed wiring installations.
How to wire domino switch diagram
- Isolate and verify dead Switch off the circuit breaker or remove the fuse protecting the lighting circuit you are working on. Use an approved voltage indicator to verify that all conductors at the switch location are dead before removing the existing switch or touching any wiring.
- Identify the conductors and their functions In the UK (post-2004 harmonised colours), a single-way switch connection uses brown for the permanent live, blue (sleeved with brown) for the switch wire, and green/yellow for earth. In other countries, follow your local colour code. Identify whether a neutral is present at the switch position if required.
- Connect the switch module For a single one-way switching module: connect the permanent live (or switch feed) to one terminal and the switched live (going to the luminaire) to the other. For two-way switching: connect per the two-way diagram relevant to your wiring configuration. Earth the mounting box and earth terminal on the module if provided.
- Fit the module into the frame Clip the wired module into the mounting frame or grid. Ensure all conductors are neatly folded and no copper is exposed outside terminals. The module should seat flush and click into the frame retaining mechanism.
- Fix the frame to the mounting box Secure the frame to the back box using the fixing screws provided. Do not overtighten — plastic frames can crack. The frame must sit flush against the wall surface with no visible gap.
- Clip on the face plate Press the decorative face plate firmly over the frame until it clips into place. Some systems use small securing screws; others are clip-only. Ensure the switch rocker operates freely and does not bind against the plate opening.
- Restore power and test Restore the circuit breaker. Test each switch function: the controlled light or load should operate correctly, and in a two-way circuit, each switch should independently toggle the load. Check for any sign of sparking, buzzing, or warm plates that would indicate a wiring fault.
Specifications
| Typical switch module current rating | 10 A or 16 A |
|---|---|
| Typical switch module voltage rating | 250 V AC |
| Back box depth (standard) | 25 mm or 35 mm |
| Cable size (lighting circuit, typical) | 1.0 mm² or 1.5 mm² (verify per applicable code) |
| Applicable standard (UK) | BS 7671 (IET Wiring Regulations), 18th Edition |
| Applicable standard (USA) | NEC/NFPA 70 |
| Applicable standard (AU/NZ) | AS/NZS 3000 |
| Applicable standard (international) | IEC 60364 |
Safety warnings
- All fixed wiring work on lighting circuits must comply with the applicable electrical installation standard for your country: BS 7671 (UK), NEC/NFPA 70 (USA), AS/NZS 3000 (Australia/NZ), IEC 60364 (international). In most jurisdictions, fixed wiring work must be carried out by a licensed electrician and may require inspection and certification. Do not carry out this work yourself unless you are qualified and permitted to do so under local regulations.
- Always isolate the circuit at the consumer unit or distribution board and verify dead with an approved voltage indicator before removing any switch or touching any conductors. Do not rely solely on the switch being in the off position — the live conductor is still energised at the switch.
- Earth continuity is mandatory. The mounting back box and any earthed switch module terminals must be connected to the circuit protective conductor (CPC). A missing earth is a dangerous fault.
- Do not exceed the current rating of the switch module. Using a 6 A module on a 13 A ring circuit supplying multiple luminaires can cause the module contacts to overheat and arc.
Tools needed
- Approved voltage indicator (non-contact and contact type)
- Flat-head and cross-head screwdrivers
- Wire strippers (calibrated to the cable cross-section used)
- Continuity tester or multimeter
- Electrician's side cutters and pliers
- Torch or head lamp for working in ceiling voids or dark enclosures
- Cable detector/pipe and cable scanner (before drilling or chasing)
Common mistakes
- Connecting the permanent live to the wrong terminal on a two-way module, which causes the light to be permanently on or permanently off depending on switch position.
- Omitting the earth connection to the metal back box, leaving the metalwork unearthed and creating a shock hazard.
- Using push-in terminals with stranded conductors that are too fine for the terminal's clamp range, resulting in a high-resistance or intermittent connection.
- Installing a dimmer module without checking compatibility with the lamp type — incompatible dimmer-lamp combinations cause flickering, buzzing, or reduced lamp life.
- Not sleeving the bare earth conductor with green/yellow PVC sleeving before terminating at the switch, which is a code violation in most jurisdictions.
Troubleshooting
- Light is permanently on regardless of switch position
- Cause: Switch is wired across the neutral rather than the live, or a two-way switch has the permanent live on L1/L2 instead of Common Fix: Isolate the circuit. Identify the permanent live with a voltage indicator before isolation, then verify wiring connections match the correct diagram for your configuration. Correct any miswired terminals.
- Light does not come on in any switch position
- Cause: No live at the switch, broken switch contact, or an open circuit in the switch wire going to the luminaire Fix: Restore power and use a voltage indicator to confirm live is present at the Common terminal of the first two-way switch. Check continuity of the switch wire with the circuit isolated. Test module contact continuity by pressing the switch while testing across its terminals.
- Dimmer module buzzes when light is on
- Cause: Incompatible dimmer-lamp combination, dimmer is a leading-edge type with LED loads, or load is at or below the dimmer's minimum load threshold Fix: Verify the dimmer is rated for LED/CFL loads (trailing-edge type) if LED lamps are fitted. Check total load is within dimmer's minimum-to-maximum range. Some dimmers have a trim adjustment screw to reduce buzzing at the minimum load setting.
Frequently asked questions
What is a domino switch and how does it differ from a standard switch?
A domino switch is a modular system where individual switch modules click into a shared frame or face plate. Unlike a conventional switch where the mechanism and plate are one unit, domino switches allow modules to be swapped (standard switch, dimmer, USB socket) without changing the frame, and face plates to be swapped without disturbing wiring.
How do I wire a two-way domino switch?
Each two-way switch module has three terminals: common (C), L1, and L2. At the first switch, connect the permanent live to C, and the two-way cable cores to L1 and L2. At the second switch, connect the two-way cable cores to L1 and L2, and the switched live (going to the light) to C. The exact conductor colours follow your local wiring regulations.
Can I use a dimmer module in a domino switch frame?
Yes, provided the dimmer module is rated for the lamp type. LED and CFL lamps require a trailing-edge (electronic) dimmer; incandescent and halogen lamps work with either leading-edge or trailing-edge dimmers. Always check the dimmer's minimum and maximum load rating against the total wattage being controlled.
What is the difference between push-in terminals and screw terminals on switch modules?
Push-in (back-stab) terminals clamp the conductor with a spring mechanism — connection is faster but can have higher contact resistance over time if the conductor is too thin or not fully inserted. Screw terminals provide a more reliable mechanical connection and are preferred by many electricians for critical or permanent installations.
Do I need a neutral at the switch for modern smart domino switch modules?
Most traditional domino switch modules do not require a neutral — they interrupt the live feed only. However, many smart/Wi-Fi switch modules require a neutral conductor at the switch position to power their electronics. Check the requirements of the specific smart module before installation and ensure your switch wiring includes a neutral if needed.
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