Guide: how to install a smart switch

Preparing to install a smart switch

Replacing a wall switch with a smart model requires careful preparation. Before beginning any work, gather the right tools, verify that the existing wiring is compatible, and secure the electrical circuit.

Secure the circuit before disassembly

To install a smart switch, you must first turn off the main power at the electrical panel before touching any wires. Once the circuit breaker is turned off, use a voltage tester to verify that there is no current in the wires: this check eliminates any risk of electric shock, even on a circuit you believe to be de-energized. Make sure that no one can turn the circuit breaker back on while work is being performed.

• Use a phillips or flathead screwdriver, depending on the type of screws used to secure your existing light switch.
• Voltage tester—essential for verifying the absence of current before handling the conductors.
• Stripping pliers for removing insulation from the ends of wires without damaging the conductor.
• Wire connectors (domino or Wago type) for securely connecting wires to each other after installation.

Next, remove the wall plate from the old switch, unscrew the mounting screws, and carefully pull the mechanism out of its box. Before unplugging anything, take a photo of the existing wiring or label each wire: this simple precaution prevents any confusion when connecting the new appliance, especially in older installations where the live and neutral wires do not always follow standard markings.

Check the hardware and compatibility

A Wi-Fi-enabled light switch operates on the 2.4 GHz band: the first factor to consider when choosing a model is to verify that your Internet router is broadcasting this network and that the signal is stable where the switch will be installed. Some devices also use Zigbee 3.0, a wireless protocol that relies on a home automation hub rather than the router itself.

Depending on the layout of the home, the presence or absence of a neutral wire in the wall box determines which model to choose: some smart switches require this wire to function, while others do not. Always check the manufacturer's specifications and compare them with the wiring you observe after disassembly to avoid an unnecessary product return.

The depth of the recessed box is another factor to check, especially in thin walls. In practice, you should also check compatibility with your light fixtures: some smart dimmers only work with LED bulbs that the manufacturer has certified as compatible. Hager switches designed for smart home projects offer interchangeable mechanisms and plates within each product line, which helps prevent selection errors.

Add a wireless remote control

A battery-powered wireless switch can be added to the system without modifying the existing circuit. This type of additional control unit, which can be mounted on the wall or placed freestanding, transmits its commands via radio or through a micromodule integrated into the chosen home automation ecosystem. This is the best option when you need to add a second control point in a room without having to run new cables.

This simple solution is suitable as long as it is compatible with the existing gateway or hub. Some home automation starter kits come with a wireless controller and a receiver module included, which simplifies setup. Home automation and its applications They thus cover both wired and wireless connections, depending on the specific requirements of each home.

Connect the switch wires

Once the old mechanism has been removed from its box, connecting the new unit follows a specific procedure. It is crucial to correctly identify each wire before connecting anything: a mistake at this stage can damage the electronic module or cause a short circuit.

Identify the live wire, the neutral wire, and the lamp return wire

Before making any connections, you must interpret the wiring diagram for a wireless switch by taking into account the actual colors found in your junction box, since french installations predating the NF C 15-100 standard do not always follow current color codes. The phase wire is usually black and connected to terminal L; the lamp return wire is connected to terminal 1 in a standard lighting circuit.

• Phase (L terminal): typically a black wire that is constantly live and connected to the L terminal of the new switch.
• Lamp return (terminal 1): wire leading to the light fixture; connect to terminal 1 according to the manufacturer's diagram.
• Neutral: often a bundle of white wires folded back at the rear of the housing; required on certain connected models.
• Ground: green wire or bare copper wire; install according to the manufacturer's instructions and the existing wiring.

To identify the line wire in a two-point control system, briefly turn the circuit breaker back on after removing the mechanism, then test each terminal screw with a voltage detector. The driver who answers is the line. Immediately turn off the circuit breaker before proceeding with any electrical connections: this precaution is non-negotiable.

Wiring a single-pole switch or a two-way switch

In the first case, the connection is direct: the phase wire is connected to L, and the lamp return wire is connected to 1. In the second case, the smart switch is installed only in the box that contains the line wire and replaces the old mechanism on its own.

It is not recommended to install two connected switches to create this type of circuit: a single connected module and a standard switch as the second component are sufficient in most configurations.

Reinstall the equipment safely

Once the connections are complete, carefully tuck the wires into the box, taking care not to pinch them, and then slide the mechanism into the recessed mounting. Align the mounting holes, tighten the screws evenly without applying excessive force, and make sure any curvature in the wall plate is pointing upward before snapping it into place or screwing it in. Improperly positioned equipment can interfere with the visibility of the controls.

Once reassembly is complete and the plate is in place, restore power to the electrical panel. A bare wire protruding from a junction box poses an immediate hazard until power is restored: do not restore power until you have completed the installation. The Wi-Fi setup can then begin, as the module is now powered on and ready to receive its network settings.

Set up home automation and the smart switch

Once the physical installation is complete, setting up the home automation system is the final step before you can control the lighting from a phone or tablet. In practice, it only takes a few minutes if your home Wi-Fi network is stable.

Pair the switch with Wi-Fi

Create an account in the app associated with your switch and log in before you start adding the device: most apps won't detect any modules until the user is logged in.

Pairing begins when the module enters pairing mode, which is usually indicated by a flashing light whose color varies by manufacturer. Next, start the process of adding a device in the app; the module will appear in the list of detected devices, and you simply need to select it to proceed to the network setup step. Communication takes place on the Wi-Fi band between 2.4 and 2.4835 GHz: a stable network at this location is essential for connecting the module.

• Flashing light: indicates that the module is in pairing mode and ready to be detected by the app.
• Enter Wi-Fi credentials: the credentials for the 2.4 GHz network must be entered in the app to connect the module.
• Indicator light status change: indicates that the module is establishing a connection to the home Wi-Fi network.
• Steady indicator light or confirmation in the app: indicates that setup was successful and that the switch is properly connected to the network.

Once the connection is confirmed, the switch is operational and can be controlled from the app. The exact meaning of the indicator lights is provided in the manufacturer's manual. Please note that some home automation ecosystems require you to first purchase a starter kit that includes a gateway in order to use additional wireless controls.

Controlling the lighting after configuration

To learn how to install a Legrand wireless switch or any other connected module and get the most out of it, explore the app’s features after setup: scenarios, schedules, dimming, and presence simulation are the most useful options for everyday use. This feature allows you to turn on the lights remotely to secure your home during a prolonged absence.

The physical push button remains fully functional after installation, without relying on a smartphone or the Internet. Commands can also be given by voice if the ecosystem is compatible with a voice assistant. The app also centralizes control of multiple connected devices, eliminating the need to switch between different interfaces depending on the type of device.

Choose a compatible product line

DomeaShop carries several Hager product lines designed for different applications: Essensya for standard residential installations, Gallery for decorative finishes in Pure, Night, Dune, or Titane colors, and Cubyko for home automation projects featuring KNX modules and an IP55 protection rating. The Ateha surface-mount series is designed for walls that are too thin for recessed installation, with the same IP55 rating, while the 1930 series is ideal for older homes seeking a retro style.

Depending on the level of protection required, the decision between a recessed series and a surface-mounted IP55 series may need to be made as early as the project design phase, particularly for a kitchen or bathroom. DomeaShop offers a full range of accessories and mounts to complete any installation—from single-station setups to multi-station configurations—allowing you to install mechanisms and faceplates that are compatible with your selected equipment.