Shelly for Home Assistant: smart plug, relay or power meter?

Your favourite lamp doesn’t need replacing. Your washer doesn’t need Wi-Fi. Sometimes the smartest upgrade is a small box that gives the appliance you already like one useful new trick.

Choose Shelly Plug US Gen4 for plug-in switching and power readings, Shelly 1 Mini Gen3 for a dry-contact retrofit, or Shelly PM Mini Gen3 when you want to measure a wired load without adding a relay. The names are close; the jobs are quite different.

Specs and setup guidance come from Shelly and Home Assistant; this is a research-based guide.

The three good jobs for a Shelly

Start with the plug if your appliance already has one. Shelly Plug US Gen4 gives you an outlet switch and power/energy readings, without opening a wall box. Put a lamp on a dashboard, see what a desk setup draws, or use its readings in an automation. Our local smart-plug guide compares it with other ecosystems.

Choose 1 Mini Gen3 when the existing control is the part you want to make smart. Its potential-free, or dry, contact behaves like an electrically separate switch. That is useful for a compatible control input, not just for switching the module’s own supply voltage. It does not add power metering.

Choose PM Mini Gen3 when the question is “what is this appliance doing?” It is a meter, not a remote off button. That makes it an appealing route for a wired appliance you want to monitor while leaving its normal controls alone. The washer notification below uses that distinction.

The two Mini listings are two-packs; the Plug US listing is one white plug. You are choosing a role first, then the quantity your project needs.

Compare switching, metering and power requirements

Pick	What it does	Supply and neutral	Maker rating to plan around
Shelly Plug US Gen4	Outlet switching plus power and energy readings	120 V, 60 Hz wall outlet; no wall-box retrofit	15 A; 1,800 W is the resistive-load maximum
Shelly 1 Mini Gen3	One dry-contact relay; no power meter	110–240 VAC on line and neutral terminals	Switching: 8 A at 240 VAC or 5 A at 30 VDC
Shelly PM Mini Gen3	One metering channel; no relay	110–240 VAC on line and neutral terminals	Measurement: up to 16 A and 240 VAC

Sources: Shelly’s Plug US Gen4 specifications, 1 Mini Gen3 specifications and PM Mini Gen3 specifications. The PM Mini component list also shows its metering role.

Keep the units attached to the job. A measurement current is not a switching rating, and the 1 Mini’s 30 VDC contact rating does not mean you can power the module from DC. Its own supply is AC. Likewise, the plug’s resistive-load maximum is not a blanket motor-load allowance.

The Mini model codes in these maker documents are S3SW-001X8EU and S3PM-001PCEU16. Mains wiring belongs to a qualified person where local code requires it; have them select the locally approved model, load protection and enclosure for your installation.

Gen2, Gen3 and Gen4: what matters in Home Assistant

The most useful generation fact is pleasantly boring: the official Shelly integration supports all four generations. You do not need to replace a working Gen2 device just to get local Home Assistant control.

Home Assistant’s Shelly documentation says Gen2 and newer use RPC to communicate with HA. Main-function changes arrive as push updates, and the integration communicates directly with the device without a cloud connection. Its IoT class is Local Push. Some diagnostic entities poll; that does not turn the main switch and meter experience into a cloud service.

Gen3 brings a more advanced processor and increased memory compared with the corresponding Plus Mini predecessor, according to Shelly. For this purchase, the bigger decision is still relay versus meter. A newer processor will not turn a PM Mini into a switch.

Gen4 adds a radio/protocol choice on this plug. Shelly documents Wi-Fi, Bluetooth, Matter and Zigbee support for Plug US Gen4. Its instructions distinguish the default Matter firmware from the alternative Zigbee firmware. For the setup here, keep it on Wi-Fi and use the native Shelly integration for its local controls and readings. Save a Zigbee move for a deliberate change of ecosystem, not a second simultaneous pairing experiment.

Already building a Zigbee network? The coordinator guide helps with that route. For a wider collection of local projects, start at the Home Assistant hub.

Plug-in or hidden retrofit? Follow the appliance

For a lamp or another suitable plug-in load, the Gen4 plug is the easy win. You keep the appliance, keep the outlet and gain a switch plus a graph. Move it to another project later without rearranging the wiring.

For a compatible control input, the 1 Mini’s dry contact is the useful feature. Its relay input and output are separate from the module’s line and neutral supply. A normal wall switch can remain part of a properly designed retrofit, so visitors still have an ordinary button to press. Decide that physical behaviour with the installer before choosing the dashboard layout.

For a wired load that should stay under its existing controls, PM Mini gives you observation. A power graph can trigger a message without triggering a power cut. It is particularly handy when the appliance’s own display is around a corner and its end-of-cycle beep never reaches you.

Neither Mini is a no-neutral shortcut. A crowded switch box with no neutral changes the installation choice; the “Mini” name only describes the module’s size. For clamps, several circuits or whole-home readings, use our CT energy-monitoring guide instead.

Add it to Home Assistant locally

1. Get the Shelly onto your Wi-Fi. Use the device’s setup interface and keep its local web interface available for configuration.
2. Open Settings → Devices & services in Home Assistant. Add the discovered Shelly, or choose Add integration → Shelly and complete the manual setup.
3. Open its device page. Name the switch or power sensor after its job, such as Desk lamp or Washer power, so the automation editor stays readable.
4. Watch a real change: switch a suitable load on, or run the appliance and see its power reading move. The PM Mini should give you measurements, not a relay control.
5. Add the useful entities to your dashboard. Start with watts for “what is happening now” and energy for longer-term consumption.

The integration’s setup and data-update sections are the reference if discovery or updates need attention. Gen2+ normally needs no extra protocol configuration; the special outbound-WebSocket instructions there concern battery-operated devices, not a step to copy automatically for these mains-powered picks.

Make the washer announce the finish

The best smart-home message is the one that saves you another trip to the laundry. Use the PM Mini’s power reading, a Toggle helper and the Companion app to make it happen. The same pattern works with another suitable power sensor already in HA.

First, graph a complete cycle. Pick an “actually running” level and a “finished” level that stay clear of the machine’s ordinary pauses. The following 10 W for two minutes and below 3 W for five minutes are starting examples; tune them to your washer.

Create a Toggle helper named Washer running under Settings → Devices & services → Helpers → Create helper. Start it Off. The Toggle helper documentation covers its on/off behaviour.

1. Arm the reminder when the cycle starts

In a new automation, use Numeric state crossed threshold, select the washer power entity, set Above: 10 and For at least: 00:02:00, then add the action to turn on Washer running.

alias: Washer - arm the finish reminder
triggers:
  - trigger: numeric_state
    entity_id: sensor.washer_power
    above: 10
    for: "00:02:00"
actions:
  - action: input_boolean.turn_on
    target:
      entity_id: input_boolean.washer_running
mode: single

2. Send one message when it settles down

Create another automation with Below: 3 and For at least: 00:05:00. Add a state condition requiring Washer running to be On. Send the phone notification, then turn the helper Off so idle power does not keep earning congratulations.

alias: Washer - tell me it is done
triggers:
  - trigger: numeric_state
    entity_id: sensor.washer_power
    below: 3
    for: "00:05:00"
conditions:
  - condition: state
    entity_id: input_boolean.washer_running
    state: "on"
actions:
  - action: notify.mobile_app_your_phone
    data:
      title: Laundry victory
      message: The washer has finished. Rescue the clothes!
  - action: input_boolean.turn_off
    target:
      entity_id: input_boolean.washer_running
mode: single

Replace the example entities with yours. Numeric-state triggers fire on a crossing, which is exactly the order this recipe uses: power rises to arm the helper, then falls to finish. Companion notifications supply the phone action; the power readings and automation are local, while phone delivery follows the Companion notification route.

Give the reminder a proper dress rehearsal

Use Run actions on the finish automation to test message delivery. Then turn the helper Off and test the real sequence: a power rise that arms it, followed by a drop that sends one notification and clears it. Simply changing a threshold and pressing Save does not simulate that crossing.

Watch the graph through wash, rinse, spin and any long pauses. If a pause earns a premature “victory”, lengthen the below-threshold duration or adjust the finish threshold to match the cycle. Keep the automation focused on a message; leave the appliance’s power alone.

Pending duration waits are discarded on restart or automation reload, and the sensor needs another qualifying crossing to trigger again. After a restart mid-cycle, reset the helper and follow the next full cycle to put the reminder back in sync.

Pick the plug for an outlet, the 1 Mini for a dry contact, and the PM Mini for a reading. Then give the old appliance one genuinely useful new trick. Fresh laundry beats another app icon.