Shelly Relays

The PM is power metering, and it changes more than the reporting. A 1PM measures the load it switches, so it has to sit in that circuit. A plain Shelly 1 gives you a potential-free dry contact instead, isolated from its own supply, so it can switch a circuit at a completely different voltage.

The Shelly 1L and 2L are built for it, and both come with the Bypass they need. The Bypass has to go next to the light rather than next to the relay, which is a second spot your electrician has to reach. The no-neutral channel caps at 200 W. On the 2L only the first channel carries that limit; the second runs to 700 W.

Four, and they change what your wall switch does rather than what the relay does. Toggle suits a rocker, where the switch position matches the light. Edge also suits a rocker, but each flip toggles the light, so either position can be on. Momentary is for a push button, where each press toggles it. Detached separates the two: the switch stops operating its own circuit and becomes a free input your automations can read, so a flick of the old switch can run a scene instead. Toggle and Edge need the input set to Switch, Momentary needs Button, and Detached works with either.

Gen4 for anything new. It carries Wi-Fi, Bluetooth and Zigbee 3.0 with Matter support, and it wires up the same as every generation before it. The one exception is the no-neutral job: the 1L and 2L we stock are Gen3. Shelly makes Gen4 versions of both, we just don't have them yet.

Yes. Every Gen2 and later device runs a local web interface and works standalone on your own Wi-Fi network, so the wall switch, the schedules and any local automations carry on if the connection drops. What you lose is the remote half: controlling it from the app while you are out, and anything that runs through the cloud. The switch on the wall never depends on the internet at all.

A dry contact is a relay output that carries no voltage of its own. Shelly's own word for it is potential-free: the contact simply opens and closes, and whatever it switches brings its own supply. That is what a garage or gate motor wants, and it is how you switch low-voltage gear. The catch is that you choose one or the other. A model without PM gives you the dry contact, while a PM model has to sit in the circuit it measures, so it cannot be isolated from it.

Because that is normal. A relay switching a load sheds heat, and in a sealed wall box it has nowhere to go. Shelly rates these for an ambient working temperature up to 40 degrees and builds overheating protection into the device. Warm in the wall box is designed behaviour. One that is cutting out is not, and that is worth a call.