Shelly Dimmers

Trailing edge and leading edge are the two ways a dimmer can cut the mains power reaching a light. Both switch that power on and off many times a second, far too fast for you to see, and the difference is which part of each pulse they cut off. Trailing edge is the gentler of the two on modern LED, so you get less buzz from the globe and less flicker at low brightness. Leading edge is the older method and suits halogen and incandescent globes. Every Shelly dimmer is trailing edge, and there is no leading edge model in the range.

No. A smart bulb has its own electronics inside it and expects full mains power all the time, while a dimmer works by reducing the power that reaches the light. Put one behind the other and you get flicker, bulbs that will not start, or a light that stops answering its app. Philips Hue list their bulbs as not compatible with dimmers for this reason. If the light is already smart, set the brightness in its own app and leave the circuit at full power. If you want the wall switch in an app as well, a relay does that job without dimming the supply.

Only the Pro Dimmer 2PM. It is a DIN-rail unit with two independent channels, each dimming its own circuit at up to 200 W. The in-wall Dimmer Gen3 and Gen4 are single channel, so two circuits means two modules, and each one has to reach the wiring for the circuit it controls.

With either, one at a time. The Gen4 ships on the Matter profile, and five presses of the control button switch it to Zigbee, which opens a three-minute window to pair it with a Zigbee system. It cannot run both profiles at once, so pick the one your setup speaks. The Dimmer Gen3 and the Pro Dimmers have neither.

Usually because the dimmer has not calibrated to the load. The in-wall models calibrate the first time the light is switched on, and have to be calibrated again after any change to the lights on the circuit. Swapping globes counts. If it still flickers at the bottom after a recalibration, the load is probably under the minimum, which is what the Bypass is for.

Only if you are running an in-wall Dimmer Gen3 or Gen4 without a neutral and the lights on that circuit add up to less than 20 W, which two or three LED downlights can easily do on their own. The part matters because of where it goes: the Bypass is fitted behind the light, not next to the dimmer, so your electrician needs it in hand on the day and needs to reach the fitting as well as the wall box. It also settles a lamp that glows faintly when it should be off.

Not with the models we stock. These dim the mains supply to the light, which suits dimmable LED globes and most integrated fittings. A fitting with a 0-10V or DALI driver expects a control signal instead. Shelly makes dimmers for both, and we don't range them yet, so ask us before you order.

Yes. A Shelly dimmer wires into fixed mains wiring, which in Australia is work for a licensed electrician. The module itself is quick, usually fifteen minutes or so in the wall box. If you are running without a neutral on a small load, have the Bypass on site for the same visit, because it is fitted at the light rather than at the dimmer.