Four dimmers over the same table, or six down a corridor, need to rise and fall together. There are three ways to get that, and they are not equivalent: one works instantly and without internet, and the other two do not.
The three methods, best to worst
1. Local actions — the good one
One dimmer is made the master and given local actions that push its brightness level to the others. The command travels over your own Wi-Fi, device to device, without touching a server.
It is instantaneous and does not depend on internet. If the line drops, the group carries on. It is the only one of the three that makes them feel like a single light.
2. Groups in the app
You put the dimmers in a group inside the app. Good for driving them from the phone or by voice, and the quickest to set up. But the group lives in the app: press the wall button on one of them and the others know nothing about it.
3. Cloud scenes
A trigger sets several dimmers to fixed levels. It works, but it needs internet and is slower: you see a stagger as it comes on, lights arriving one after another rather than together.
Fine for a “cinema” or “dinner” scene, where the delay almost adds to it. Not fine for making a corridor come up evenly.
How many actions fit
Each Gen3 dimmer takes up to 20 actions, with up to 5 destinations per action. That is 100 possible destinations from a single master — ample for any home, and enough for most small commercial installations.
If you ever run out, they chain: the master tells five, and one of those five tells another five.
The condition almost nobody meets
For the group to dim coherently, the dimmers must be the same model carrying the same load.
That sounds demanding, and there is physics behind it: 30% on a dimmer is not an absolute quantity of light, it is a point on its dimming curve, and that curve depends on the driver facing it. Two different fittings at the same 30% give different brightness.
The gap widens at the bottom of the range, where LEDs behave least predictably. At 80% you may notice nothing; at 15% you will see one lit and one dark.
With no neutral, the bypass is not optional
Under 20 W per point with no neutral, you need a bypass. Without one you get flicker and standby glow, and that ruins the synchronisation: you cannot match a group whose members are each flickering to their own rhythm.
It is explained in why the bulb glows or flickers, and the fitting in how to install a bypass, step by step. Note: a dimmer’s bypass is not the same part as a no-neutral relay’s.
Recalibrate every time you change a bulb
A dimmer learns the curve of the load connected to it. Swap a bulb for a different model or wattage and that curve no longer applies, and that point falls out of step with the rest of the group.
Recalibration is a 5-second press on the device button. It is the step almost nobody takes, and it explains half the groups that “broke on their own”.
Checking the group is still even
The console shows every dimmer’s level in one list. If one has drifted out it is obvious at a glance, without walking room to room — which is how you catch it before somebody complains.
The console and the app work with Gen2, Gen3 and Gen4.
How to use both, section by section: mobile app manual and web console manual.