Shelly wiring diagrams, terminal by terminal

The explorer above asks what you are trying to do first, then which relay you are using, and draws the wiring for that pairing. It is the same diagram that sits on that relay's own product page, from the same data, so the two can never drift apart.

The rest of this page covers the same ground in words, because a diagram is only useful once you know what its labels mean.

Everything electrical below comes from Shelly's own knowledge base, and where Shelly publishes an Australian page for a model, that is the one we have used. The four Gen4 relays have ANZ pages. The Gen3 models are published without a region, so those are what we have worked from for them. The distinction matters: for the Shelly 1 Gen4, the European page lists 24-48 V and 12 V DC supply modes that the Australian device does not have, and quoting the European figures here would be wrong. One wording note: Shelly's legends label the supply conductor "Live", and we call it the active, which is the Australian term for the same wire.

What each terminal does

L and N, the supply

These power the relay itself, at 110-240 V~ on the Gen4 models. Shelly's spec sheets for the 1 Gen4 and 1PM Gen4 answer the line "neutral not needed" with "No", and the rest of the range apart from the 1L has an N terminal on the strip, so plan on a neutral being present at the relay. Some models carry more than one of each: the 1PM Gen4 strip has three L terminals and two N, and the 2PM Gen4 has two L and one N.

O, the load circuit output

This is the switched active conductor that goes out to the light or appliance. The 2PM has two of them, O1 and O2, one per channel.

I, the load circuit input

Only the Shelly 1 and the 1 Mini have this terminal. On those two the relay contact is potential-free, which Shelly also calls volt-free or a dry contact: in Shelly's own words the output carries no voltage or current from the relay itself, so whatever you connect across I and O is joined or separated and nothing more. In the ordinary lighting job our diagram bridges I from L, so the contact switches mains. In the garage door job it doesn't, and that is what the terminal is for.

SW, the switch input

Shelly's legend describes SW as controlling the O output. The existing wall switch lands here, so the switch on the wall keeps working alongside the app. One thing to be blunt about: in every diagram on this page the wiring to the wall switch is fed from the active conductor, so SW sits at mains potential. Treat it as a mains terminal, not as an extra-low-voltage signal wire. The 2PM calls its two switch inputs S1 and S2. The 1L uses S1 and S2 as well, plus an Sx terminal that sends the switch signal back out to the wall switches.

The Gen3 models can run on a DC supply as well as mains, and the Gen4 ones sold here can't. On the 1PM and 2PM that isn't an extra pair of terminals: the same N and L screws take the DC supply instead, N as the positive and L as the negative. Only the 1 Gen3 has DC terminals of its own. The diagrams show the AC arrangement throughout, which is what nearly every Australian installation uses.

The six jobs

Switching a light or appliance

The common one. Mains comes in on L and N, O carries the switched active conductor out to the light, and the wall switch lands on SW. On the Shelly 1 a short bridge from L feeds the I terminal, because the contact needs something to switch. On the 1PM there is no bridge to make, and the relay meters the circuit on the way through.

Switching a light with no neutral

This is the 1L Gen3, and it is a different drawing rather than a variation. There is no N terminal on the relay. It powers itself through the load circuit, and Shelly's own note is that an LED light on it needs a Shelly Bypass wired across the lamp, while an incandescent lamp does not. The Bypass is in the box. The 1L is rated at 200 W and takes incandescent and LED lamps without step-down transformers, so it suits a light rather than an appliance. Sx loops the switch signal out to the wall switches on S1 and S2, so an existing one-way or two-way arrangement keeps working. The neutral hasn't gone anywhere in this job, it just doesn't come to the relay.

Switching two lights

This is the 2PM. Each channel is its own switched and metered circuit: O1 to the first light, O2 to the second, with the wall switches on S1 and S2. Mains comes in once on L and N and feeds both. The rating is per channel and shared: 10 A on each output, 16 A across the relay.

Pulsing a garage door opener

The job the potential-free contact exists for. The opener wants a brief connection across the two terminals its own push button uses, and nothing else. I and O run as a dry contact across those terminals, with no mains passing through them, while L and N power the relay alone. The pulse length is set in the Shelly app. A push button can go on SW if you want a physical trigger as well.

Driving a roller shutter or awning

This puts the 2PM in cover mode, where it drives the motor one way at a time. One output winding opens and the other closes, which is which comes out in calibration, and the motor's common returns to neutral. S1 and S2 take optional open and close buttons. Shelly's advice is to use a motor with electronic or mechanical limit switches, and to have those set correctly before the relay is connected to it.

Metering an appliance

This is the 1PM wired exactly as it would be to switch a light, and the wiring is not what you are here for. Put a heater or a towel rail on O and the relay reports what it is drawing and what it has used, with the switching as a bonus. Anything with a motor in it counts as an inductive load, which Shelly's supported-load list qualifies as needing an RC snubber, so that is a detail for your electrician rather than an afterthought. If you want the measurement without the switching, the energy monitors are built for that job instead.

Which relays we have drawn

Nine relays have diagrams today: the Shelly 1, 1 Mini, 1PM and 2PM in both Gen3 and Gen4, plus the 1L Gen3.

Two groups aren't drawn yet, and neither is a comment on the hardware. The Pro range mounts on a DIN rail in the switchboard rather than behind a wall switch, so it needs a different body drawing rather than another scenario on an existing one. The 1PM Mini Gen4 hasn't been drawn yet. Both are on the list, and a relay having no diagram here doesn't make it harder to install or a worse choice for the job. If the model you are looking at has no diagram, ask us and we will get you the manufacturer's own.

If you are still choosing between models rather than working out how to wire one, Which Shelly do I need? covers that, and what a Shelly is rated to switch covers the loads. The whole range sits on the Shelly relays page.

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