The Shelly Pro EM-50 (model SPEM-002CEBEU50) is a single-phase, two-channel energy meter for DIN rail. It's the only one in the Pro range that has a built-in relay, which considerably simplifies installation if you want to drive a contactor.
This guide covers the step-by-step installation using data from Shelly's official documentation.
Before you start
Cut the supply at the main switch and verify the absence of voltage with a multimeter before touching anything. If you don't have electrical training, this installation should be done by a professional.
Also check that you have room on the DIN rail: the unit takes up 94×19×69 mm, that is, one standard module.
Wiring diagram
1. Power supply
Connect the live to L and the neutral to N. The unit accepts 100 to 260 V at 50/60 Hz and draws less than 3 W. Protect the supply with a type B or C breaker, 16 A maximum.
Tighten the terminals to a maximum torque of 0.4 Nm and use conductor of 0.5 to 2.5 mm² stripped between 6 and 7 mm.
2. Current transformers
The Pro EM-50 has two clamp inputs: IA for the first channel and IB for the second. Each channel handles up to 50 A.
Place each clamp around a single phase conductor, with the arrow pointing in the direction of current flow towards the load. If, on powering up, you see negative values where you expected positive ones, the clamp is the wrong way round.
3. Relay for a contactor
Terminals I (input) and O (output) form a galvanically isolated dry contact, with a maximum of 2 A at 240 V.
That output is for driving the coil of a contactor, not for powering the load directly. An electric water heater or a pump needs an intermediate contactor rated for its power.
4. Network
You can connect it via Wi-Fi, Ethernet or Bluetooth. If you use the RJ45 port, always connect or disconnect the cable with the unit powered off, and make sure the connector has no exposed metal parts.
First start-up
- Restore the supply. The power LED will light up red.
- Press and hold the button for 5 seconds to enable the unit's access point. The Wi-Fi LED will turn blue.
- Connect to the
ShellyProEM50-XXXXXXnetwork and set up your Wi-Fi, or add it from the Shelly app. - Verify that the two channels' readings are consistent and that the signs are as expected.
A short press of the button toggles the built-in relay. Ten seconds held down performs a factory reset.
How to interpret the LEDs
- Blue: access-point mode, pending setup.
- Red: no connection to the Wi-Fi network.
- Yellow: connected to Wi-Fi but no cloud.
- Green: connected to Wi-Fi and to Shelly Cloud.
- Red/blue flashing: firmware update in progress. Don't cut the power.
Data you'll get
The unit measures in 4 quadrants, so it distinguishes consumption from generation. It records active and apparent power, active and apparent energy, voltage, current and power factor, with an accuracy of 1% between 5 and 50 A (2% below 5 A).
It stores at least 60 days of history at one-minute resolution in non-volatile memory, exportable to CSV and JSON. The internal clock keeps the correct time even if the internet goes down.
Common installation mistakes
- Clamp over phase and neutral at once: the fields cancel and the reading drops to nearly zero.
- Load connected directly to the relay: it exceeds 2 A and damages the unit. Always use a contactor.
- Clamp cable extended too much: it picks up electrical noise and generates phantom readings.
- Network cable connected with the unit powered: it can damage the port.
If the readings don't add up, check our guide on why a Shelly meter reads more than expected: the causes are the same across the range.
Related products
- Shelly Pro EM-50: the single-phase, two-channel meter with a built-in relay.
- Shelly meter comparison: if you're still not sure which one you need.
Questions about your specific panel? Write to us and we'll help. Technical support in English and shipping from Spain.
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