Smart switches for home lighting not working: causes, safe checks and repairs
Most smart switches for home lighting stop responding for one of three reasons. The switch has lost power, it has lost its link to the hub or network, or a part inside it has worn out.
You can safely check the first two from your phone and your fuse board. The third needs a technician.
This guide covers older systems. In these homes the switches went in some years ago, and the original installer may have moved on. Before you start, one rule: do not take the switch off the wall. There is mains electricity behind the faceplate.
First, work out what has stopped
The parts that still work show you where the fault is. Try the switch by touch, then from the app, then wait for a schedule to run. Note what happens each time.
- Touch and app both fail: the switch has probably lost power, or a part inside it has failed.
- Touch works but the app does not: the link between the switch and the hub has broken. A hub is the small box that links your devices to the app.
- Touch and app work but the schedule does not: the problem is usually in the hub's settings or clock.
- The light flickers, or glows faintly when off: the bulb may not suit the switch.
Common causes in older systems
Older systems usually fail in one of a few ways. Here are the common causes.
- A tripped breaker. A breaker is the switch in your fuse board that cuts power to one circuit. If it trips, every switch on that circuit stops.
- A changed router. A new router, Wi-Fi name or password can cut off Wi-Fi switches and some hubs. This often happens after an internet upgrade.
- A weak wireless mesh. Zigbee is a wireless mesh system, which means devices pass signals to each other in a chain. If one link in the chain fails, switches further along can drop off.
- A hub that has stopped working or lost its settings, for example after a power cut.
- An app or online service the maker no longer supports. Firmware, the software built into the switch, may also be out of date.
- A worn relay. The relay is the small part inside the switch that clicks the light on and off. It wears out over time.
- Heat. Makers rate switches for a set room temperature. Lutron, for example, rates its Caséta in-wall dimmers for indoor use between 0°C and 40°C. If you close your home up for the summer with the AC off, check your switch maker's rating.
- Bulbs that do not suit the switch. A dimmer and a bulb that do not suit each other can flicker. Lutron says it only recommends LED bulbs it has tested with its dimmers.
Safe checks you can do yourself
Work through these checks in order. Stop at any step that fixes it, and write down what you did.
- Check other switches in the same room. If several stopped together, the cause is likely power or the hub, not one switch.
- Look at your fuse board. If a breaker has tripped, reset it once. If it trips again, leave it off and call an electrician.
- In an apartment, if you cannot find your fuse board, ask building management where it is.
- Restart the hub. Unplug it for ten seconds, then plug it back in. Give it a few minutes to reconnect.
- Think about recent changes. Has anyone replaced the router, or changed the Wi-Fi name or password? If so, the switches may need setting up again.
- Open the app and check that the hub shows as online. Update the app if your phone offers an update.
- Check the schedule. Make sure the hub's time and time zone are right, especially after a power cut.
- Try a different bulb, of a type the switch maker lists as suitable. Some makers, Lutron among them, offer a tool that checks which bulbs work with their dimmers.
When to stop and call a professional
Some signs mean the fault is inside the switch, the wiring or the system itself. A technician should handle these, not you.
If you notice heat, a burning smell, buzzing or a scorched faceplate, turn that circuit off at the breaker. Then call an electrician the same day.
- The breaker trips again after you reset it.
- One switch is dead while others on the same circuit still work.
- The whole system still does not respond after you restart the hub.
- Wireless switches keep dropping offline. Our guide to Zigbee switches that drop offline explains what a technician looks for.
- Your home uses KNX, a wired control standard. In homes, KNX devices usually talk over their own control cable. See repairing a KNX system when the original installer has gone.
- The maker no longer supports your app or hub.
What a technician will do
First, a technician checks that the switch has power and is wired correctly. Some smart switches need a neutral wire, an extra wire that an older switch box may not have. Lutron's specification sheet for its Caséta switches, for example, says certain models need a neutral connection.
Next, they check the hub and network. They may reconnect the switch, update its firmware or move the hub so it gets a stronger signal.
If the switch itself has failed, they replace it with one that works with your system. Our guide to replacing old smart switches explains how to avoid a model that will not talk to your hub.
The cost depends on your type of system, how many switches are affected and whether the parts are still made. Before you book, ask what the first visit costs and who will do any wiring. Our guide to comparing repair quotes lists other questions to ask.
What to tell the company when you call
A few details help a technician bring the right parts. That can save you a second visit.
- The brand and model of the switch and hub. You can often find these in the app or on the hub's label.
- Which switches have stopped, and when.
- What still works: touch, app or schedule.
- What you have already tried, from your notes.
- Whether the original installer is still in business.
- A photo of the faceplate and the hub. Do not remove the faceplate to take it.
- For apartments, any access rules from building management.
Your next step
If your checks have not fixed it, ask one of the three repair companies we looked at for a consultation. Send them your notes and photos, and ask whether they work on your brand of system.