A Smart Controller Behind Your Existing Switch: How Does It Work?
Updated November 1, 2026
A smart controller is a small component installed inside the electrical box, behind the switch you already have on the wall. The switch keeps turning things on and off as usual, and the controller adds control from your phone, by time of day or by sensor. Installation in the electrical box is done by a licensed electrician.
What does the controller actually do?
The controller sits between the power supply and the device it operates, such as a lamp, a shutter or a water heater. It receives commands both from the switch and from the network, and reports to the system whether the circuit is on or off.
Why does the switch keep working?
The existing switch is connected to the controller's input. Pressing it remains the usual way to turn on a light, so even people who do not use the app notice no change. The physical wall switch always keeps working, even if something happens to the controller.
Common types of controllers
- On/off relay: For lighting, a water heater or an appliance.
- Shutter controller: To raise, lower and stop at a specific position.
- Dimmer controller: For light fixtures that support dimming.
- Controller with power metering: Lets you see how much electricity flows through the circuit.
We work with controllers from all the well-known brands, for example Shelly, and choose according to the circuit, the space in the box and the appropriate communication.
What do we check before installation?
- Whether there is a neutral wire in the box, because some controllers need one.
- Whether there is enough room in the box.
- The type of load: lighting, a shutter motor or a water heater.
- That the network reaches that point well.
Frequently Asked Questions
Who installs the controller?
The work in the electrical box is carried out by a licensed electrician. We design, configure and connect the controller to the system.
Do I need to replace the switches?
Usually not. The existing switches stay and are connected to the controller.
Does the controller work without internet?
The system runs locally in your home and keeps working at all times, as long as your router is on and broadcasting WiFi. The physical wall switch always keeps working, even if something happens to the controller, so your lighting always stays on. Phone notifications and remote access to your home from outside require a working internet connection. We take care of this service as part of a monthly fee.
Want to find out what suits your home?
We would be happy to have a short, free intro call. Tell us what you have at home today and what you would like it to do, and we will suggest a direction.
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