Does the Shelly Pro 3EM Switch Add-on work on its own?

No. It is an accessory that docks onto a Shelly Pro 3EM meter and is powered by it. Without the Pro 3EM it has neither power nor communication and cannot function.

What load can the relay output switch directly?

The relay switches a maximum of 240 V AC at 2 A (or 30 V DC at 2 A). For heavy loads use it to drive the coil of a properly sized external contactor.

Does the module have its own WiFi or Bluetooth?

No. The add-on has no radio of its own. All wireless connectivity and app communication go through the Shelly Pro 3EM meter it is attached to.

How is the accessory mounted?

It mounts on the DIN rail next to the Pro 3EM meter, in a 94 x 19 x 69 mm format. Connections use screw terminals for 0.5-2.5 mm conductors at 0.4 Nm torque.

What do the LEDs on the module indicate?

There are two red LEDs: one lights when the power supply is connected, and the other when the output relay contact is closed.

Is there a warranty and can you help choose the contactor?

Yes, the product has a 24-month warranty. The CasaSmart team can advise on contactor selection and wiring, while installation is done by a licensed electrician.

Shelly Pro 3EM Switch Add-on Relay

Name: Shelly Pro 3EM Switch Add-on - DIN relay output module for contactors
Brand: Shelly
SKU: SHELLY-PRO-3EM-SWITCH-ADD-ON

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Compatibility

Works with these ecosystems

Ecosystems

Home Assistant
eWeLink

What it is, who it's for, what it does

About this product

The Shelly Pro 3EM Switch Add-on is a DIN-rail accessory that docks directly onto the three-phase Shelly Pro 3EM meter and gives it a galvanically isolated relay output. With it, the energy-metering device can not only monitor consumption but also drive a contactor or other electrical appliances, turning the panel into a system that reacts to the readings it takes.<br><br>The module has no radio of its own: power (3.3 V and 12 V DC) and communication arrive over a dedicated serial interface from the Pro 3EM, while its own draw stays below 1 W. The relay output switches up to 240 V AC / 2 A (or 30 V DC / 2 A), enough for the coil of a contactor that in turn handles heavy loads. Two red LEDs show power presence and the state of the output contact.<br><br>The 94 x 19 x 69 mm housing mounts on the DIN rail next to the Pro 3EM, and the screw terminals accept 0.5-2.5 mm conductors at 0.4 Nm torque. With an internal temperature sensor and a -20...40 degrees C operating range, the accessory is built for the distribution board in homes and commercial spaces across Chisinau and Moldova.

Delivery
Free from 1500 MDL
Returns
30 days to return
Warranty
24 months

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CasaSmart essentials

What it works with, what it needs, what you can do

Verified compatibility

We test every device for these ecosystems. For non-standard integrations contact us before ordering.

Home Assistant
Zigbee
Matter
KNX
Wi-Fi

Install & requirements

What you need on your side and what we deliver.

Zigbee hub or Matter gateway for wireless variants
65 mm back-box or DIN panel for wired variants
Local setup on Home Assistant — included in install

Request install quote

Smart scenarios

Three typical automations we set up after the install.

01Morning: warm light + blinds up + climate at 22 °C
02Leaving: lights off, arm sensors, close the gas
03Evening: warm ambient + cinema scene

Where it works

Use cases

When total consumption drops below a threshold, the contactor turns on the water heater to use surplus energy.

The relay output drives a contactor coil to switch heavy loads on or off based on Pro 3EM readings.

In a Chisinau commercial building, electric heating is temporarily cut when three-phase power reaches the set threshold.

As the power limit is approached, the relay disconnects a non-essential load through a contactor.

A manager remotely starts the circulation pump through a contactor driven by the add-on.

Manual control of the output from the Shelly app via the Pro 3EM meter connectivity.

Analytics

See consumption — save on bills

Real-time consumption tracking via the eWeLink app. Daily, weekly and monthly history helps identify the most energy-hungry devices.

For the installer

Technical specifications

full spec · wiring · datasheet

Power

Max switching voltage AC: 240 V
Max switching current AC: 2 A
Max switching voltage DC: 30 V
Power supply (from Pro 3EM): 3.3 and 12 V DC
Power consumption: < 1 W

Connectivity

Interface to Pro 3EM: Proprietary serial

Physical

Dimensions: 94 x 19 x 69 mm
Weight: 20 g
Mounting: DIN rail
Terminal conductor: 0.5 to 2.5 mm2

Environment

Operating temperature: -20 to 40 C
Humidity: 30 to 70 % RH
Max altitude: 2000 m

Full device datasheet

Support

Frequently asked questions

Does the Shelly Pro 3EM Switch Add-on work on its own?
No. It is an accessory that docks onto a Shelly Pro 3EM meter and is powered by it. Without the Pro 3EM it has neither power nor communication and cannot function.
What load can the relay output switch directly?
The relay switches a maximum of 240 V AC at 2 A (or 30 V DC at 2 A). For heavy loads use it to drive the coil of a properly sized external contactor.
Does the module have its own WiFi or Bluetooth?
No. The add-on has no radio of its own. All wireless connectivity and app communication go through the Shelly Pro 3EM meter it is attached to.
How is the accessory mounted?
It mounts on the DIN rail next to the Pro 3EM meter, in a 94 x 19 x 69 mm format. Connections use screw terminals for 0.5-2.5 mm conductors at 0.4 Nm torque.
What do the LEDs on the module indicate?
There are two red LEDs: one lights when the power supply is connected, and the other when the output relay contact is closed.
Is there a warranty and can you help choose the contactor?
Yes, the product has a 24-month warranty. The CasaSmart team can advise on contactor selection and wiring, while installation is done by a licensed electrician.

Same ecosystem

Works together

Devices that run in the same smart-home ecosystem.

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—

Shelly

Shelly Wave PRO 2PM Z-Wave 2-channel DIN-rail relay with metering

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Same category

Questions about this product?

A CasaSmart manager calls you within 1–2 working hours and answers anything — compatibility, install, alternatives.

+373 60 944 922

Updated: 18 June 2026· reviewed by CasaSmart Expert Team

Compatibility