Sonoff · SPM-4Relay

Sonoff SPM-4Relay expansion module for SPM-Main, 4 × 20 A relays with energy metering

Name: Sonoff SPM-4Relay expansion module for SPM-Main, 4 × 20 A relays with energy metering
Brand: Sonoff
SKU: SONOFF-SPM-4RELAY
Price: 1699 MDL
Availability: InStock

1,699 MDL3 left

Energy metering relays

Manufacturer images

1,699 MDL3 left

What it needs to work

The SONOFF SPM-Main module is required.

Buy with installation

Check compatibility

Max load current per channel: 20 A
Connectivity: RS-485 (wired bus)
Mounting: DIN rail (panel)

Renting rooms or running a workshop means knowing where the kilowatt-hours go: SPM-4Relay meters four 20 A lines separately and works only paired with the SPM-Main head unit.

24 specifications from manufacturer documents

We deliver across Moldova. Availability, delivery timing and cost are confirmed with a manager before order fulfilment.

The right choice starts with specifications

Device passport

SKU: SONOFF-SPM-4RELAY · Document model: SPM-4Relay

Specifications checked against the linked manufacturer documents. Load limits, package details and measurement conditions are retained.Checked 18 October 2026

Power and load5

Max load current per channel — what it means The highest current the relay switches and measures on one channel. As a guide at 230 V: 16 A ≈ 3.7 kW, 20 A ≈ 4.6 kW, 25 A ≈ 5.8 kW, 32 A ≈ 7.4 kW — compare with your water heater, underfloor heating or heater.	20 A100–240 V ~, 50/60 Hz, 20 A per channel [1]
Max power per channel (resistive) — what it means Maximum resistive load per channel per the documentation: water heater, heater, underfloor heating. For motors and large power supplies the permitted power is lower.	Not stated by the manufacturer
Max total current — what it means Current the device handles across all channels at once. On multi-channel models the total is often lower than per-channel current × number of channels.	80 A80 A in total across the four channels [1]
Supply voltage — what it means The supply voltage (and current, if stated) as the maker gives it. It must match your mains or adapter.	100–240 V AC, 50/60 Hz [1]
Standby power — what it means How much power the device draws on its own while idle. It matters for devices that run around the clock.	Not stated by the manufacturer

Connectivity and compatibility8

Connectivity — what it means The wireless link or network the device uses. Wi-Fi connects straight to the router; Zigbee, Thread and Bluetooth Mesh work through a hub or gateway.	RS-485 (wired bus)The module talks to the SPM-Main unit over an RS-485 bus (up to 100 m, 2-core shielded RVVSP cable ≥ 0.2 mm²). SPM-Main connects to the network and cloud via 2.4 GHz Wi-Fi or Ethernet [2]
Hub required — what it means Whether the device needs a separate hub, gateway or coordinator to work in a smart home. If so, it is sold separately unless stated otherwise.	Hub (gateway) requiredWorks only together with the SONOFF SPM-Main unit (sold separately); one SPM-Main takes up to 32 SPM-4Relay modules (up to 128 channels) [1]
Matter support — what it means Whether the device supports the Matter standard, directly or through a bridge. Matter lets you add it to Apple Home, Google Home, Alexa and Home Assistant.	Not stated by the manufacturer
Works without internet — what it means Whether the device keeps working over the local network or through a hub when the internet is down. Cloud features (remote access, voice assistants) need the internet.	YesThrough the SPM-Main unit: eWeLink LAN mode and a local HTTP API (DIY mode) [1]
Home Assistant — what it means How the device connects to Home Assistant: a built-in integration, a Zigbee coordinator, Matter or the maker’s cloud integration.	Via the maker's integrationSONOFF mentions a Home Assistant integration in the SPM troubleshooting section without naming it; a local SPM-Main HTTP API exists for DIY use [1]
App — what it means The maker’s app used to set up and control the device.	eWeLink [1]
RS-485 bus length	100 mTotal, daisy-chained; the termination resistor is switched on at the last module [2]
Modules per SPM-Main	32 [1]

Housing and installation4

Mounting — what it means How and where it is installed: in a wall box, on a wall or ceiling, on a DIN rail, on a table or in a socket.	DIN rail (panel)Mounts on a DIN rail in the panel [1]
Terminal wire size — what it means Which wire sizes the terminals accept, in mm². High loads need cable of matching size, chosen by an electrician for the current and run length.	Not stated by the manufacturer
Dimensions (W × H × D) — what it means The device’s size in millimetres as the maker states it. Check that it fits the wall box, niche or shelf.	250 × 90 × 66.5 mmSPM-4Relay module only; the SPM-Main unit is 142.5 × 90 × 66.5 mm [1]
Housing material	Polycarbonate (PC), flammability class V0 [1]

Control and features5

Channels — what it means How many separate circuits the relay switches and measures. A multi-channel unit tracks each panel circuit separately.	4Four independent isolated channels; the module is powered from channel 1, so channel 1 must always be supplied [1]
Built-in display — what it means A screen on the housing shows power, voltage and consumption right at the panel, no phone needed.	NoThe housing has only indicators (communication, error, channel state) and mechanical channel switches, no screen [2]
Cut-off on set limits — what it means The device switches the load off by itself if current, power or voltage limits set in the app are exceeded. It does not replace the circuit breaker in the panel.	YesPer channel thresholds are set in eWeLink: min power, max/min voltage, max current, max power, plus a switch-off delay. SONOFF states it does not replace a circuit breaker [1]
Wired wall switch input — what it means Whether you can keep an ordinary wall switch or push button and wire it to the module, so the light works from both the switch and the app. Shows which switch types are supported; on dimmers a momentary button usually also adjusts brightness when held.	No inputTerminals: L1–L4 and N1–N4 (in and out) plus RS-485 — no wall-switch input; the housing has mechanical L1–L4 switches [1]
Power-on state after outage	Per channel: On / Off / Last state [1]

Measurement and detection3

Measured values — what it means Which values the device reports in the app. Energy in kWh lets you work out costs; voltage helps spot sags and surges on the line.	Voltage (V), current (A), power (W), energy (kWh)Per channel: real-time current, voltage, power and consumption history; consumption reports are stored on the microSD card in SPM-Main [1]
Measurement accuracy — what it means Measurement error per the documentation, e.g. ±2 % for power. Unless meter certification (such as MID) is stated, readings are for tracking use, not for billing with the supplier.	Not stated by the manufacturer
History and cost tracking	Over 20 years of data and up to 20,000 operation logs per device on microSD in SPM-Main; reports exported from the card [1]

Operating conditions1

Operating temperature — what it means The air temperature range the device is rated for. The lower limit matters outdoors, on balconies and in unheated rooms.	−10…40 °C [1]

Model and version1

Colour — what it means The housing colour of this model. Other colours in the same series are separate products.	White [3]

Package contents2

Required components	SONOFF SPM-Main unit (Wi-Fi/Ethernet); for history storage, an 8–32 GB microSDHC card in SPM-Main (not included) [3]
Manufacturer warranty — what it means The warranty period the maker states. Confirm warranty terms in Moldova with the seller.	24 months“2-Year Hassle-Free Warranty” on the official SONOFF store page; warranty terms of the regional seller may differ [3]

Manufacturer documents

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Delivery and stock

We deliver across Moldova. Availability, delivery timing and cost are confirmed with a manager before order fulfilment.

How is payment handled?

A website order is submitted for confirmation without charging your card. The payment method and final amount are agreed with a manager before payment.

Warranty and documents

The warranty is at least 12 months. The exact period and conditions for equipment and installation work are stated in the sales documents and the accepted proposal. Further support is agreed for each project.

Can I return the product?

Current conditions are published on the Return policy page. Email office@casasmart.md with your order number for the steps relevant to your situation. Statutory consumer rights continue to apply.

Delivery, payment and returns

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