Open box Main unit Sonoff SPM-Main for stackable smart meter, with energy monitoring, 20A per channel and expandable up to 128 channels with SPM-4Relay modules
Description
What does "open box" mean?
Open-box products are returned products with opened or damaged packaging, but fully checked from a technical point of view and completely functional. They come with the same warranty as new products.
Sonoff SPM-Main smart relay, 20A/channel, energy monitoring, expandable up to 128 channels
Sonoff SPM-Main is a professional smart relay designed for residential or industrial applications, offering real-time energy monitoring, WiFi control via the eWeLink app, and the option to expand up to 128 channels by connecting SPM-4Relay modules.
Ideal for electrical panels, distribution boards, lighting circuit control, industrial sockets or other power equipment, the SPM-Main delivers a complete and scalable automation and energy management solution.
Advanced control and monitoring
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20A per channel on the connected SPM-4Relay modules – suitable for high-power loads
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Real-time monitoring of electrical consumption: voltage, current, active power and energy consumed
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Access to data directly from the eWeLink app, with graphical display and detailed history
Expandable up to 128 channels
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Can be expanded with up to 32 Sonoff SPM-4Relay modules, each with 4 isolated channels
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Unified control and monitoring from the app, for each individual channel
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Ideal for multi-circuit applications (buildings, halls, offices, large homes)
Remote control via eWeLink
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Mobile app for Android and iOS
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Automations, schedules, smart scenes
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Sharing control with other users
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Compatible with Alexa, Google Assistant, IFTTT
Smart functions available:
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Individual on/off for each channel
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Daily/weekly scheduling for automation
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Notifications when a consumption threshold is exceeded
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Power-on state setting after power is restored
DIN rail mounting
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Built for direct mounting in electrical panels
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Safe, quick connection with robust terminals
Practical use cases
- Installed on the circuit of an air conditioner or a water heater, it monitors energy consumption in real time and sends alerts on abnormal values.
- Used to identify the appliances that use the most electricity in the home and reduce the energy bill.
- Integrated into an automation that automatically switches off an appliance if it exceeds a consumption threshold, preventing faults.
Technical specifications:
| Feature | Specification |
|---|---|
| Model | Sonoff SPM-Main |
| Supply voltage | 100–240V AC, 50/60Hz |
| Controllable channels | No relays of its own; 4 channels on each connected SPM-4Relay module |
| Maximum load per channel | 20A |
| Energy monitoring | Yes (voltage, current, power, energy) |
| Expandability | Up to 128 channels (with up to 32 SPM-4Relay modules) |
| Connectivity | WiFi 2.4 GHz, IEEE 802.11 b/g/n |
| Compatibility | eWeLink, Alexa, Google Assistant, IFTTT |
| Mounting | On DIN rail |
| Communication with the modules | RS-485 with the SPM-4Relay modules |
| Cloud connection | Ethernet or WiFi |
| Data storage | microSD card 8-32GB, over 20 years of history, up to 20000 logs |
| Protection | Automatic shut-off on overload |
| Housing material | Flame-retardant PC V0 |
Control, expand and fully monitor your electrical installation with the Sonoff SPM-Main – the smart, safe and scalable solution for automating power circuits in any space!