Lighting control with Shelly

Start with the wire

Smart lighting can be built four ways, and they are not equal. In order of preference:

A wired switch into the dimmer’s own input. Always the first choice.
A BLU battery switch, paired over Bluetooth, where no wire can be pulled.
An input module — Shelly I4 Gen4 or I4 DC Gen4 — where several existing switches need to reach devices elsewhere.
A Shelly 1 Mini used purely as an input, where only one switch position is needed and space is tight.

The order matters. A wire is the only connection that never needs a battery changed, never loses range, and never depends on anything else working. Wireless is an answer to a problem — not the default.

Open the tool Device finder Filter the range by application, mounting, supply voltage and metering.

Wired control — the first choice

A momentary spring switch wired to the dimmer’s SW input. The dimmer sits behind the switch or on DIN rail; the switch reports presses, and the dimmer does the rest.

This gives you everything: press to toggle, hold to dim, double-press for full brightness, and instant response whether the network is up or not. There is no pairing to redo, no battery to change, and nothing to go out of range.

Where there is already a wire to the switch position, use it. In a renovation this is often the case even when the customer assumes otherwise — an old low-voltage installation, a two-way circuit with a spare conductor, or a switch loop that can be repurposed.

A Shelly dimmer fitted in a back-box behind a wall switch — The dimmer sits behind the switch; the switch wires into the SW input.

Wireless control — when no wire can go there

A Shelly BLU Wall Switch 4 ZB — or the ZB DK variant for Danish switch systems — pairs directly to the dimmer over Bluetooth. No gateway, no Wi-Fi, no cloud.

This is the answer for a switch position with no wire: a new position on a solid wall, a glass partition, or a bedside where chasing is out of the question.

Response is instant and dimming is smooth, because nothing travels over a network. What you accept in exchange is a battery to change every few years and a range limit of roughly ten metres indoors.

The full pairing procedure is in dimming with BLU Wall Switch.

Input modules — several switches, one place

Where a group of existing wired switches has to reach devices that sit elsewhere, an input module reads the switches and passes the presses on.

Shelly I4 Gen4 reads four 230 V AC inputs. Shelly I4 DC Gen4 does the same for low-voltage inputs — the right choice when converting a 24 V bell-wire installation, where the existing switches are already low voltage.

Four inputs in one DIN module is what makes this economical: one device covers a whole switch panel.

Four Shelly I4 modules mounted on DIN rail — One I4 covers four switch positions. Several fit in a small board.

The single-switch alternative — a Shelly 1 Mini

For one switch position, an I4 is more than the job needs. A Shelly 1 Mini is the popular choice instead, and the reason is size: it fits where an I4 will not.

The trick is that you use only its input. The switch wires to the Mini’s SW terminal, the Mini reports the press over the network, and the dimmer acts on it. The Mini’s relay output is left unused entirely.

That sounds wasteful and is not: the Mini is small, inexpensive, and gives you a wired switch position anywhere there is 230 V — without a second dimmer and without a battery.

Switch settings

The setting that decides how the light feels is the button type, and it must match the switch that is physically fitted.

Setting	Use when	Behaviour
One button	A momentary spring switch or push-button	Press toggles, hold dims up and down, double-press goes to 100 %
Dual button	Two switches or a rocker pair	`SW1` on and brighten, `SW2` off and dim
Toggle	An ordinary toggle switch	Follows the switch position. No dimming from the wall
Edge	An ordinary toggle switch	Changes state on every flick, regardless of position
Detached	The input should control something else	Disconnects the input from the output entirely
Activation	A PIR or presence sensor drives the input	Turns on from the sensor rather than toggling

One button is the setting to aim for, and the reason to specify momentary switches when you get the choice. It is the only mode that gives dimming from the wall.

Button type setting in the Shelly app — The button type must match the switch actually fitted, not the one you would prefer.

Run the auto-calibration

The dimmer can detect the load type and set itself up accordingly. Run it — it takes a minute and it is the difference between a light that dims smoothly and one that flickers at the bottom of the range.

If the result is unsatisfactory, set the dimming mode by hand instead. LED lamps vary enormously, and a driver that behaves badly on one mode is often perfect on another.

The other settings worth a look

Correct configuration is most of what separates a dimmer that feels right from one that annoys. Each of these takes seconds to set and none of them are obvious from the app:

Min and max brightness — reframes the range onto the part the strip or lamp actually uses well. This is what fixes a dimmer that does nothing for the first fifth of its travel.
Button fade rate — how quickly the level moves while a button is held.
Transition duration — how smoothly the light moves on a scheduled or automated change.
Min brightness on toggle — stops the light returning at an invisible level after being dimmed almost to nothing.
Power-on state — on, off, or restore the last state after a power cut. Worth deciding rather than leaving at the default.

The video below shows each of them being set.

Tips & best practices

Specify momentary switches wherever you get the choice. A toggle switch permanently costs the customer dimming from the wall, and changing it later means opening the wall again.
Check the minimum load. A single LED bulb on a dimmer rated for far more will flicker or refuse to start. A bypass solves it where it happens.
Do not mix drivers on one dimmer. Two different LED types on the same channel will never both dim well; calibration can only optimise for one.
A wireless switch is a battery in a wall. Note the fitting date and tell the customer what to expect, or it becomes a service call in five years.
Test at the bottom of the range. Most dimming complaints are about the last 10 %, not the first 90 — and that is where calibration and driver choice show up.

Video tutorial

Dimmer settings

Calibration, min and max brightness, button fade rate and transition duration — the four settings that decide how a dimmed light feels.

Loads YouTube when you press play. Watch on YouTube

By ShellyGuide on YouTube

PIR control with a constant-on override

Motion control with a manual override — the arrangement that keeps a PIR-controlled light on when someone needs it to stay on. Common in meeting rooms and outdoor lighting.