Shelly Pro EM-50

Device identification

Name: Shelly Pro EM-50

Model: SPEM-002CEBEU50

Device SSID: ShellyProEM50-XXXXXX

Short description

Shelly Pro EM-50 is a professional-grade two-channel, single-phase energy meter with a built-in relay for
contactor control. Designed for DIN rail mounting, it combines the flexibility of Gen2 firmware with
advanced connectivity options including LAN, Wi-Fi, and Bluetooth. The device provides real-time monitoring
of voltage, current, active and apparent power, as well as total energy consumption.
Shelly Pro EM-50 stores up to 60 days of 1-minute interval data and includes a real-time clock to maintain
accurate timestamps even without network synchronization. It can operate standalone or as part of
an automated system via MQTT, HTTP, and WebSocket protocols with TLS encryption.

Main features

• 4-quadrant measurement
• DIN rail mounting
• Two-channel single-phase monitoring
• Current transformer connection
• Built-in dry-contact relay for external contactor control
• Optical pulse indication of energy usage
• Real-time clock ensures accurate logging during outages
• Up to 60 days of data logs with 1-minute intervals
• Accuracy Class B (IEC 62053-21)
• Photovoltaic system compatible

Main applications

• Residential
• MDU (apartments, condominiums, hotels)
• Light commercial (offices, small retail, restaurants, gas stations)
• Agricultural (farms, barns, silos)
• Government / municipal buildings
• University / college campuses

Simplified internal schematics

Shelly Pro EM internal schematics

Device electrical interfaces

Inputs:

2 line inputs on screw terminals: 1 × L and 1 × N

2 current transformer inputs: IA and IB for current measurement

Outputs:

2 galvanically isolated relay terminals: I and O

Ethernet port:

1 × RJ45 connector

⚠ CAUTION! Plug or unplug the LAN cable only when the device is powered off. The LAN connector must not have
metallic parts exposed to touch.

Add-on interface:

Shelly proprietary serial interface

⚠ CAUTION! High voltage is present on the add-on interface when the device is powered.

Connectivity

Wi-Fi

Ethernet

Bluetooth

Each connectivity option can be enabled or disabled by the user.

Safety features

Overheating protection

Supported load types

• Resistive (incandescent bulbs, heating devices)
• Capacitive (LED drivers, capacitor banks, electronic equipment)
• Inductive (transformers, fans, refrigerators, air conditioners)

User interface

Inputs:

One tactile dome button

• Short press → Toggle built-in relay

• Hold 5 s → Activate Device AP

• Hold 10 s → Factory reset

Outputs:

LED indication

• Power → Red when power supply is connected

• Wi-Fi:

  – Blue = AP mode

  – Red = STA mode (not connected)

  – Yellow = Connected to Wi-Fi (Cloud disabled)

  – Green = Connected to Wi-Fi and Shelly Cloud

  – Flashing Red/Blue = OTA update in progress

• LAN → Green when connected

• Out → Red when output relay contact is closed

• Count → Red flashing according to measured energy frequency

Physical

Size (HxWxD): 94×19×69 mm ±0.5 / 3.70×0.75×2.71 in ±0.02

Weight: 63 ±1 g / 2.22 ±0.05 oz

Mounting: DIN rail

Screw terminals torque: 0.4 Nm (4.43 lbf·in)

Conductor size: 0.5–2.5 mm² (20–14 AWG; solid, stranded, and bootlace lugs)

Strip length: 6–7 mm (0.24–0.28 in)

Shell material: Plastic

Color: White

Environmental

Ambient temperature: −20 °C to 40 °C (−5 °F to 105 °F)

Humidity: 30–70% RH

Max altitude: 2000 m (6562 ft)

Electrical

Power supply (AC): 100–260 V~, 50/60 Hz

Power supply (DC): N/A

Power consumption: < 3 W

Output ratings

Max switching voltage AC: 240 V~

Max switching voltage DC: N/A

Max switching current: 2 A

Sensors & Meters

Internal temperature sensor: Yes

Voltmeter (RMS): 100–260 V

Voltmeter accuracy: ±1%

Ammeter (RMS via CT): 0–50 A

Ammeter accuracy: ±1% (5–50 A), ±2% (0–5 A)

Power & energy meters: Active and apparent power; active and apparent energy; power factor

Measurement data storage: At least 60 days at 1 min data resolution

Data export: CSV for PQ recorded values; JSON format export via RPC

Radio

RF band: 2400–2495 MHz

Max RF power: < 20 dBm

Wi-Fi protocol: 802.11 b/g/n

Wi-Fi range: Up to 30 m / 100 ft indoors; 50 m / 160 ft outdoors (depends on conditions)

Bluetooth protocol: 4.2

Bluetooth range: Up to 10 m / 33 ft indoors; 30 m / 100 ft outdoors (depends on conditions)

MCU

CPU: ESP32-D0WDQ6

Flash: 16 MB

Firmware capabilities

Webhooks: 20 (up to 5 URLs each)

Scripting: Yes

MQTT: Yes

CoAP: No