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Power metering Shelly troubleshooting

Shelly power reading shows zero or looks wrong

The watts read 0, go negative, or the energy total doesn't add up. Check the device meters at all, then the output, the settings and the counters.

Checked

  • Gen4

Start here

What are you seeing?

Pick the closest match and we'll point you to the fix most likely to sort it.

Go to the fix

Why it happens

A Shelly with metering measures the power its circuit draws and adds it up into an energy total. The 1PM, 2PM and 1PM Mini measure through their relay output, so what they read depends on whether that output is on.

Most wrong readings come down to that, a setting or a reset counter, and the device's web page shows which.

Before you start

These checks are done in the Shelly app or a browser. Changing the wiring, adding a neutral or swapping the device is a job for a licensed electrician. Don't open the wall plate.

Quick checks first

Run these checks before moving on to the fixes.

Checklist 0 of 3 checked
Check it's a model that meters

The 1PM, 2PM and 1PM Mini Gen4 measure power, and so does the EM Mini Gen4. The Shelly 1 Gen4 and 1 Mini Gen4 don't.

Read it on its web page

Open the device's web page. The home page shows the power in watts with the voltage and current beside it.

Check the output is on

If the voltage shows but the watts read 0, look at whether the output is on before anything else.

Fixes, most likely first

Work down the list and stop when it's fixed.

  1. The output is off

    How to tell. The voltage reads normally and the power reads 0 W. On the 1PM, 2PM and 1PM Mini, Shelly measures power through the relay output, so nothing flows while it's off.
    • Turn the output on

      Turn it on from the app or the power button on its web page, then read the power again.

    • Check the load is on too

      A lamp or appliance with its own switch turned off draws nothing, even with the Shelly on.

  2. The model doesn't measure power

    How to tell. There's no power, voltage or energy reading anywhere. Shelly's spec for the Shelly 1 Gen4 and 1 Mini Gen4 lists no power meter.
    • Use a model with PM in the name

      For a reading, the circuit needs a 1PM, 2PM or 1PM Mini Gen4, or an EM Mini Gen4. Swapping the device is wiring work, so ask a licensed electrician.

  3. An output protection switched it off

    How to tell. The load was running, then the output turned off and the reading dropped to 0. Shelly's output protections switch the output off when the power, current or voltage passes a limit.
    • Check the limits

      On its web page, go to Settings, click the output, then Output protections (Protections on the Dimmer Gen4). Check the Overpower, Overcurrent and Overvoltage values aren't set below what the load normally draws.

    • Turn on Auto recovery if you want it

      With Enable Auto recovery on, Shelly turns the output back on once the reading is back under the limit, if it was on before.

  4. The measurement direction is reversed

    How to tell. The power shows as negative, or the energy counts into Energy returned instead of Energy consumed.
    • Turn off reverse measurement

      On its web page, go to Settings and click the output. Turn off Reverse power measurement. On the EM Mini Gen4 the setting is called Reverse CT measurement direction.

    • Restart it

      Shelly says the reverse setting needs a restart to take effect. Go to Settings and click Reboot.

  5. The counters were reset

    How to tell. The energy total went back to zero and started counting again, without a firmware update or a power cut that you know of.
    • Check who reset it

      The output's settings have Reset counters, which sets the totals back to 0, and the EM Mini Gen4 has Delete stored data. Shelly keeps the totals through a power cut on current firmware, so a reset is the usual reason.

    • Use the history instead

      For a total over a period, use the app's consumption charts, which keep the history, rather than the counter on the device.

  6. It only meters its own circuit

    How to tell. The total is well under your power bill. A 1PM or 2PM measures the circuit through its own output, and the EM Mini Gen4 measures the one circuit it's wired into.
    • Compare like with like

      Compare the Shelly with the one appliance or circuit it measures, not the bill for the whole house.

    • Check the app's energy settings

      In the app's device settings, check Appliance type. Grid source adds the energy to what you used. Generated energy adds it to what you produced. Energy calculation can leave a device out of the room or account totals.

  7. The dimmer has no neutral

    How to tell. A Dimmer Gen4 dims the light but shows no watts. Shelly says it can't measure power without a neutral connection.
    • Ask an electrician

      Adding a neutral is wiring work for a licensed electrician. Shelly also says the dimmer's protections may not work properly without one.

On your device

Shelly EM Mini Gen4 It has no relay
  • It always measures

    The EM Mini Gen4 is a meter with no output to switch, so it's never off. A reading of 0 W means nothing on its circuit is drawing power.

  • Its totals are in two lines

    Its web page shows Energy consumed and Energy returned separately. Energy in the returned line points to the reverse setting.

Shelly EM Mini Gen4

Frequently asked questions

No. The Shelly 1 Gen4 and 1 Mini Gen4 switch a load without measuring it. The 1PM, 2PM and 1PM Mini Gen4 measure it.

Watt-hours. 1,000 Wh is 1 kWh, the unit on your power bill.

No. Shelly says energy measured in either direction is added to the total, and the returned energy is counted separately as well.

Scripts that help

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