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SONOFF Smart Stackable Power Meter (SPM) 4-Relay (4-gang relay) unit

Sonoff’s Smart Stackable Power Meter (SPM) is a professional category, DIN-rail compatible, stackable relay with power meter and overload protection, with up to 20A per channel max. capacity. It can save consumption to a memory card (not an accessory).

This is SPM’s 4-Relay unit, with 4-gangs of relays and power meters, with max. 20A per gang maximum output. SPM Main unit is sold separately.

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Factory SKU ID:
Supported protocols:
Ethernet / LAN, Wi-Fi
in stock (30+ pcs)

【Connect up to 32 pcs. of SPM-4Relays】One SPM-Main unit can be connected to 32 SPM-4Relays. Each SPM-4Relay has 4 isolated channels to help you manage devices more conveniently.
【Power metering】You can monitor the power consumption by checking eWeLink App on your mobile phone. Obtaining current, voltage and power easily.
【Max. 20A/Gang】Each channel can support maximum current of 20A, no fear of high power load.
【Communicated by RS-485】The SPM-Main communicates with the SPM-4Relays through RS-485, which allows for multi-terminal and stable long-distance data transmission.
【Overload Protection】Once the overload protection is enabled, it can protect your devices from burning out.


SONOFF Smart Stackable Power Meter consists of

(1) a main unit with built-in Wi-Fi chip and support for eWeLink IoT cloud and eWeLink app, and

(2) one or multiple SONOFF Smart Stackable Power Meter 4-Relays.



SPM MAIN unit is sold separately.


They all fit onto DIN rail of an electric cabinet, and provide smart control and power metering feature with max. performance of 20A per gang, as well as, overload protection for all gangs. It is a high performance professional smart home tool to manage homes, office buildings, industrial buildings or even shopping malls to keep track of residents or tenants power consumption.



The SPM Main unit communicates with the eWeLink cloud through Ethernet or Wi-Fi, and communicates with the SPM-4relay modules via RS-485, which allows multi-terminal and stanle long term data transmission. One main unit can work with up to 32 pcs. of 4-relay units, so has a total support of 128 x 20A channel management and power metering.

The device has an SD card slot, you may insert an SDHC memory card (not included with the product) to store up to 180 days consumption data and check the data via HTTP API. Data can also be exported.


Sonoff SPM Wiring:



Product features:

  • Remote ON / OFF – Anytime, anywhere, from now on you can turn all your channels on and off remotely.
  • Possibility to add up to 32 pcs. of 4-channel power metering relays to the main channel, total support for up to 128 independent channels
  • Fits to DIN-rail
  • SD card support: supports adding a 8GB-32GB SDHC memory card to store up to 180 days consumption data
  • Controling the channels independently
  • Physical on/off buttons on the 4-relay devices
  • Overload protection for all channels
  • Mobil App – free iOS és Android mobil App: eWeLink, connecting to eWeLink IoT cloud
  • Sync status – Check actual relay status (turned ON or OFF) with the mobile App
  • Share control – Control the device together with your family


Product type:
stanckable 4-gang relay unit of professional, high performance control and power metering unit
Device power supply:
100V-240V AC
230V AC (live and neutral)
DIN rail compatible:
Embedded relay:
Dimmer feature:
Power consumption metering:
Number of gangs / circuits:
Rated voltage (output):
100V-240V AC
Physical on/off button on device:
4 buttons
External switch supported:
2-way or 3-way switching:
no, SPM Main unit has WiFi
RF transmitter / receiver:
Controllable from internet:
yes, via SPM Main module
Voice control:
Cloud mode:
default mode is connecting to the eWeLink cloud via SPM Main module
Schedulers, timers:
yes, 8 timings on the device in offline mode, (loop control supported), any further timing can be run from the cloud in online mode
up to 180 days power metering history stored on memory card (sold separately)
670 g/pcs
Package offers
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SONOFF Smart Stackable Power Meter (SPM) 4-Relay (4-gang relay) unit
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