Shelly Pro 4PM in Electrical Panels: DIN-Rail Power Telemetry & Automation Guide

Electrical breaker panels are notoriously hostile RF environments. Surrounding smart relays with grounded steel enclosures attenuates 2.4GHz Wi-Fi and Zigbee signals by up to 25dB. The Shelly Pro 4PM bypasses this vulnerability with a native RJ45 10/100 Ethernet port designed directly for DIN-rail mounting.

1. Electrical Topology & Protection Suite

• Channel Capacity: 4 independent channels rated at 16A per channel, with a maximum aggregate device load of 40A across all channels.
• Individual Power Metering: High-precision current transformers sample voltage, current, active power, and apparent power per channel with ±1% calibrated accuracy.
• Flame-Retardant Shell: V-0 rated polycarbonate housing designed for standard EN 50022 top-hat rail mounting.
• Thermal Throttling: Internal temperature sensors automatically trip relays if enclosure internal temperatures exceed 95°C.

2. Local API Protocols: Modbus TCP, MQTT & WebSocket

Shelly’s Gen2 firmware operates entirely locally without requiring cloud account registration:

• Modbus TCP: Easily streams telemetry registers directly into commercial SCADA and building management systems (BMS).
• Local WebSocket & MQTT: Publishes power state changes sub-millisecond to Home Assistant and Node-RED instances.
• Onboard mJS Scripting: Allows custom JavaScript automation routines to run directly on the ESP32 microcontroller, ensuring load shedding continues even if the home automation server crashes.