What can a Shelly switch? Load ratings explained

The calculator above sizes one load against every Shelly we can verify a rating for. The rest of this page is the same data written out: what each model is rated to switch, which load types Shelly lists it for, and where the figures come from.

Every number here is read off Shelly's own Australian and New Zealand documentation. Where a model has a separate ANZ page, that page wins, because the ANZ and EU documents for the same model number differ electrically. A lot of what ranks for these questions quotes 230 V European figures, and those are the wrong figures for an Australian wall.

Load type matters more than the wattage

A relay's headline rating is a current. Shelly states it against the local mains, so a 16 A model is rated 16 A at 240 V, which is roughly 3,840 W of resistive load.

That number is only half the answer. Every product page also carries a "Supported load types" list, and the classes on it are what actually decide whether a model suits your job. A heater is resistive and draws close to its rated current the whole time it runs. A motor, a transformer or a wall of LED drivers behaves differently at the moment of switching, and the inrush is what damages relay contacts. This is why a 2,000 W heater and 2,000 W of LED downlights are not the same load, even though the wattage matches.

So the rule this page and the calculator both follow: if a model's page doesn't list the class of load you're switching, it isn't suitable, whatever the watts say. That exclusion comes from the documentation being silent, not from a safety factor we applied.

The wall-box relays

These are the models that fit behind an existing switch. If you're still choosing between them on job and wiring rather than on load, Which Shelly do I need? covers that ground.

Two things in that table are easy to read past.

The minis are half the relay. 8 A is about 1,920 W, which is plenty for lighting and comfortable for most appliances, and short of a 2,400 W heater. The 2PM pair are 10 A on each channel but 16 A across the device, so two channels can't both run at 10 A. The total is the binding number when you're switching two loads at once.

And the minis list "Inductive" plainly, where the 16 A relays list "Inductive with RC Snubber". Both are transcribed exactly as Shelly publishes them, and we've left the difference alone rather than tidying it up.

The no-neutral relays are rated in watts

The 1L and 2L are the models built for a plate with no neutral behind it, and they are rated differently: a switching power in watts, not a current. Both are lighting relays.

The 1L takes 200 W, and the page lists incandescent and LED lights only, explicitly not through step-down transformers for low-voltage fittings. No motor or heater class appears on it, which is why the calculator will never send a fan or a heater to a 1L no matter how small the load is.

The 2L is the one asymmetric device in the range. Output 1 takes 200 W and output 2 takes 700 W, and it's output 2 that also carries fluorescent lights and fans. If you're running a fan off a 2L, it has to be on output 2, and the calculator names the output for that reason. Both models ship with the Shelly Bypass. LED loads need it fitted and incandescent loads don't, and on the 2L that requirement is scoped to output 1.

The Pro relays do the same job from the switchboard

Pro isn't a step up in capability, it's the same switching packaged for a DIN rail. Shelly generations has the full comparison.

The device totals are the figures to watch, because most of them come in under the sum of the channels. The Pro 4PM is 40 A across four 16 A channels rather than 64 A, and the Pro 2 and Pro 2PM are 25 A across two rather than 32 A. The Pro 3 is the exception, at a full 48 A across its three. Plan the busiest circuits against the total, not the per-channel number.

Dimmers are rated by lamp family

A dimmer's maximum isn't one figure, it's one per lamp family, and LEDs are always the tightest of them.

The 150 W LED ceiling on the wall-box dimmers is the number that catches people out. A dimmer advertised at 200 W is quoting its incandescent figure, and dimmable LEDs come in 50 W under it. In practice 150 W is a lot of LED downlights, but it's worth doing the sum rather than assuming.

The minimum matters too, and in the opposite direction. Run a wall-box dimmer without a neutral on less than 20 W of load and it needs the Shelly Bypass fitted to work properly. Too little load is a real failure mode on no-neutral dimming, and it usually shows up as flicker.

The 0-10 V unit is the odd one. It doesn't dim by cutting the mains waveform at all: it switches the load like a relay and sends a separate 0-10 V control signal, so the fittings need drivers that accept one. There's no lamp wattage window published for it, because the driver sets that.

Blinds and covers go to the cover devices

Cover motors are their own case. The Pro Dual Cover/Shutter PM lists exactly one supported load class, "Bi-directional AC motors with RC Snubbers", and it's the only load class on that page. The 2PM and the Pro 2PM run one cover each in cover mode.

So the calculator sends a blind or awning motor only to devices that can actually run a cover, and won't offer you a plain relay for the job even when the wattage would fit. Any cover motor needs its own limit switches, set before the device is connected.

There are no derating multipliers on this page

This is the part worth being explicit about, because most load calculators work the other way.

Shelly publishes one switching figure per model, plus the list of load classes that model supports. For every relay and dimmer on this page, it publishes no second, lower figure for inductive loads. It qualifies them instead: the class is listed as "Inductive with RC Snubber", meaning the load is supported once a snubber is fitted.

We could have invented a multiplier, cut every inductive result by some factor and called it conservative. We didn't, for two reasons. A made-up number is indistinguishable from a real one once it's on a page, and the qualifier Shelly actually publishes is more useful than a factor: it tells your electrician to fit a component, which is an action, rather than shrinking a number, which is a guess.

So three rules run underneath the calculator. Inductive loads are sized against the stated figure and carry the snubber requirement as a hard caveat. A device whose page doesn't list your load's class is not suitable, whatever the wattage. And a device with no verifiable published rating doesn't appear in the results at all.

One number on this page is ours rather than Shelly's, and it's the line between "recommended" and "will work". A load at or under 80 per cent of the stated capacity comes back recommended; between 80 and 100 per cent it comes back as workable with the reason shown. That 80 per cent is ordinary electrical headroom practice, not a Shelly specification, and we'd rather say so than let it look like one.

When nothing in the range fits

Some loads are simply past what an in-wall relay does. A ducted unit, a large motor or a hot water element can sit well above 16 A, and stretching a recommendation to reach it is the one thing this tool won't do.

The usual answer is a contactor: a heavy-duty switch on the board, driven by a small Shelly relay through a dry contact. The Shelly does the deciding, the contactor does the switching, and the load never passes through the Shelly at all. That's a conversation with your electrician rather than something to size from a product page.

If what you actually want is to see what a circuit is drawing before you decide, the Shelly energy monitors measure without switching anything.