Smart switch Sonoff SPM-4Relay 4-channel Wi‑Fi relay module 4×20A

Sonoff SPM-4Relay smart switch is a 4-channel Wi‑Fi relay module with four independent outputs, each rated up to 20 A. Used together with the SPM-Main module (sold separately), it enables per-channel power measurement and centralized control for home or commercial electrical systems. The unit is designed for DIN-rail mounting and provides overload protection and remote monitoring via the eWeLink app.

Advantages

The Sonoff SPM-4Relay supports four independent channels with individual switching and a maximum load of 20 A per channel (80 A total). When paired with the SPM-Main it provides accurate power consumption measurement and stable long-distance data transmission over RS-485, while the SPM-Main connects to the cloud via Ethernet or Wi‑Fi. The device includes overload protection and load-delay features and is sized for convenient DIN-rail installation.

Suitable for

• Remote control and monitoring of apartment or multi-tenant energy consumption
• Power management in offices, retail centers and commercial premises
• Protection and control of equipment in server rooms and cryptocurrency mining rigs
• Centralized switching and automation of lighting and appliances

Key specifications

• Brand: Sonoff
• Model: SPM-4Relay
• Channels: 4 independent channels
• Rated current: 20 A per channel, 80 A max.
• Input / Output: 100–240 V ~50/60 Hz
• Material: PC V0
• Dimensions: 250 × 90 × 66.5 mm
• Connectivity (with SPM-Main): RS-485 control; SPM-Main connects via Ethernet or Wi‑Fi

How to use

Mount the SPM-4Relay on a DIN rail and connect each load to one of the four output channels following local electrical codes. Install and configure the SPM-Main (sold separately) to enable power measurement and cloud connectivity; the SPM-Main communicates with SPM-4Relay devices over RS-485. Use the eWeLink application to assign channel names, create schedules, monitor real-time consumption and set overload thresholds. Ensure correct wiring and that the total current does not exceed device ratings.

Recommendations

For reliable operation, pair each SPM-4Relay with an SPM-Main for centralized measurement and cloud access, confirm that each circuit does not exceed 20 A, and follow local electrical safety regulations when installing and wiring the device.