Load-shedding is part of daily life in much of Pakistan, so before spending money on smart switches it is fair to ask: what happens when the electricity goes? The short answer is that a smart switch is an electrical device like any other. When its circuit has no power, it cannot switch anything. But with the right setup, your smart home can keep working on a UPS or inverter, and recover cleanly when WAPDA or K-Electric supply returns. This guide explains how, and covers the safety points that matter most.
What happens during a power cut
When the supply to a smart switch's circuit goes off:
- The switch and the lights it controls turn off, exactly like a normal switch.
- The switch shows as offline in the app until power returns.
- Your settings, pairing and schedules are stored in the device and the app, so you do not need to set it up again afterwards.
What matters is not the switch alone, but the whole chain: the circuit the switch is on, your Wi-Fi router, your hub (for Zigbee), and your internet connection.
If your lights are on a UPS or inverter circuit
Many Pakistani homes wire selected lights and fans to a UPS or inverter. A smart switch on a backed-up circuit keeps working during load-shedding, because from the switch's point of view the power never went off. The switches we sell are rated for 100–240 V AC at 50/60 Hz (for example the SONOFF M5 Matter, SONOFF ZBM5 Zigbee and SONOFF MINI ONE (MINI-1GS)), and Aqara rates the Aqara Z1 at 220 V~, 50 Hz.
For control from your phone to keep working too, the other parts of the chain also need backup power:
- Wi-Fi and Matter switches such as the M5, MINI ONE, POW Elite and BASIC-1GSP need your Wi-Fi router to be on. For control from outside the house, your internet connection must also be up.
- Zigbee switches such as the ZBM5, ZBMINI-L2 and Aqara Z1 need the Zigbee hub to be on. Local scenes on hubs such as the SONOFF Zigbee Bridge Pro can run without internet, but app control from outside needs the router and internet.
- Physical buttons on the wall switch keep working whenever the switch itself has power.
If your router and hub are not on the UPS circuit, a small dedicated backup is a good investment. For example, the EcoFlow RIVER 3 has a 245 Wh LiFePO4 battery, 300 W rated AC output and a UPS switchover of under 20 ms according to EcoFlow, which suits a router and hub. To estimate runtime, divide the battery's watt-hours by the total watts of the connected devices (from their labels), then allow a margin for conversion losses.
When the power comes back
Pay attention to how each device behaves when supply returns:
- Power-on state: many SONOFF devices let you choose in the eWeLink app whether the relay comes back on, stays off, or returns to its previous state after a power cut. The SONOFF POW Elite 20A lists power-on state memory as a feature. For a geyser or heater, set it to stay off so it does not switch on unexpectedly.
- Schedules: a schedule that was due while the power was off should not be expected to "catch up" afterwards. Check important timers after the first outage.
- Reconnection: Wi-Fi devices reconnect once the router has booted; Zigbee devices reconnect once the hub is back. A minute or two of "offline" after power returns is normal.
UPS and inverter tips for smart switches
- Check the output waveform. SONOFF and Aqara rate their switches for normal AC mains. They do not publish ratings for specific inverters, so we recommend a pure sine wave UPS or inverter for circuits with smart electronics.
- No-neutral switches and LED flicker: no-neutral switches pass a tiny current through the bulb to stay powered and need a minimum load (3 W on the ZBM5 and Z1). If bulbs glow faintly on inverter power, use bulbs above the minimum load, or use a neutral switch where a neutral is available. Read Neutral vs No-Neutral Smart Switches.
- Keep heavy loads off the inverter. A geyser, heater or iron on a SONOFF POW Elite 20A or SONOFF BASIC-1GSP 32A can drain an inverter battery very quickly. Use automations or schedules so heavy loads only run on mains supply.
- Stay within ratings. Smart switches have per-gang limits; the 3 gang M5 is 2 A per gang. Do not connect a load bigger than the rating just because the inverter can supply it.
Safety notes
- Isolate both sources. A circuit fed by an inverter or UPS can still be live when WAPDA/K-Electric supply is off. Before working on any switch box, switch off the mains breaker and the inverter/UPS output, then test with a voltage tester.
- Use a qualified electrician. SONOFF and Aqara both state that installation should be done by a professional electrician.
- Protect each circuit. SONOFF specifies an MCB or RCBO of the correct rating before its switches, for example 10 A for the 1 and 2 gang M5, and 6 A for the 3 gang M5 and the ZBMINI-L2.
- Never back-feed. Inverter, generator or UPS output must never be connected to the mains side of the board. Use a proper changeover arrangement installed by an electrician.
- Keep neutrals separate and correct. On mixed inverter and mains wiring, make sure each smart switch's neutral belongs to the same circuit as its live. Mixed-up neutrals between circuits are a common cause of faults and can be dangerous.
- Allow for voltage fluctuation. If your area has frequent voltage spikes when supply returns, consider a stabiliser or surge protection for your board. Damage from wiring faults or burnt devices is not covered by any warranty, including ours.
A load-shedding-friendly smart home setup
- Put the main lights you need during outages on the UPS/inverter circuit, controlled by SONOFF M5 Matter or SONOFF ZBM5 Zigbee switches.
- Put the router and hub on UPS power or a small power station such as the EcoFlow RIVER 3. See Power Stations & Backup.
- Use a SONOFF POW Elite 20A or SONOFF BASIC-1GSP 32A for the geyser, with power-on state set to off.
- Add a SONOFF R5 Scene Controller or Aqara Wireless Mini Switch wireless button for the lights you use most, so control still feels like a normal switch.
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Not sure which switch fits your board? Send a clear photo of the wires inside your switch box on WhatsApp (+92 301 9365882) and we will tell you which model fits before you buy. Order online with Cash on Delivery anywhere in Pakistan, or visit House Sync at Shop No. 3, Prince Center, Saddar, Karachi. Bulk or project quotes: sales@housesync.store.
Warranty: every item is covered by our 7-Day Checking Warranty. Installed items are repaired or replaced after checking. Burnt devices and wiring damage are not covered.