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Smart plugs and lighting, and the wall switch trap
Bulbs, switches or plugs, the mistake that catches almost everybody once, and an honest look at what energy monitoring tells you.
Three ways to make a light controllable, and picking the wrong one for a fitting is behind most of the frustration in this whole category.
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Three ways to make a light controllable
Picking the wrong one for a given fitting is behind most of the frustration in this category, and it is worth deciding deliberately rather than buying whatever is on offer.
| Suits | Main limitation | |
|---|---|---|
| Smart bulbs | Lamps and fittings where you want colour or per-bulb control. Renting. Anywhere the wiring cannot be touched. | Stops working the moment somebody flips the wall switch. Cost multiplies with every bulb in a multi-bulb fitting. |
| Smart switches | Ceiling lights, multi-bulb fittings, anywhere people naturally reach for the switch. | Involves mains wiring and usually a neutral conductor. Not reversible in a rented home. No colour. |
| Smart plugs | Floor and table lamps, and any plug-in appliance you want scheduled or measured. | Controls the whole socket only. No dimming, and the lamp's own switch has to stay on. |
A workable rule: where a fitting has a wall switch people actually use, a smart switch is usually right. Where it is a lamp in a socket, a plug or a bulb works well. Where you want colour, it has to be bulbs.
The common trap
Why the wall switch defeats a smart bulb
This deserves its own section because it catches nearly everyone once, and it is the reason a good many people conclude smart lighting does not work.
A smart bulb needs continuous power to stay on the network. Its own electronics are what turn the light on and off, and it draws a trickle even when it appears off. Cut power at the wall and it vanishes from the application, stops answering, and will not run its schedule. To anything asking, it is simply gone.
The frustrating part is that this stays invisible until it happens. Everything works perfectly until a guest, a housemate or your own muscle memory flips the switch on the way out of the room.
Ways around it
- Use a smart switch instead for that fitting. The cleanest answer where the wiring allows, because the wall switch keeps behaving exactly as people expect.
- Leave the wall switch permanently on and control the light another way. Practical, and it requires everybody in the house to cooperate, which in practice means a note on the switch for a while.
- Fit a switch guard. Inelegant, effective and cheap.
- Put a smart button near the old switch, so there is still something intuitive to press that does the right thing.
Worth thinking about before buying: who else uses this room? Bulbs suit rooms where you control the habits, such as a home office or a bedside lamp. In a shared sitting room or a hallway with visitors, a switch is usually the less annoying choice even though it costs more effort up front.
Specifications
Choosing bulbs without the jargon
Fitting comes first
Bulb fittings vary by region. Screw and bayonet are both common, in more than one size, alongside spotlight fittings for downlights. Smart bulbs are sometimes slightly larger than the equivalent ordinary bulb, which matters in an enclosed or shallow fitting.
Brightness is measured in lumens, not watts
Watts measure power consumed rather than light produced. That was a workable proxy when every bulb was incandescent. LEDs produce far more light per watt, so wattage now tells you very little. Lumens is the figure to compare, and most packaging also gives an equivalence, which is a reasonable shortcut.
Colour temperature, in Kelvin
| Around | Appearance | Usually suits |
|---|---|---|
| 2700K | Warm, yellowish. The familiar look of a traditional bulb. | Sitting rooms and bedrooms. |
| 4000K | Neutral white. | Kitchens, bathrooms, workspaces. |
| 5000K and above | Cool, bluish daylight. | Garages, workshops, task lighting. |
Bulbs come in three broad varieties: fixed white, tuneable white which adjusts across the warm-to-cool range, and full colour. Colour costs more and, in practice, most households leave them on warm white most of the time. Tuneable white is frequently the better value unless colour genuinely appeals.
Do not put smart bulbs on an existing dimmer switch. The dimmer interrupts the supply in a way the bulb's electronics are not built for. The usual results are flickering, buzzing, an unreliable connection or a shortened life. Where a fitting has a dimmer and you want smart bulbs, the dimmer wants replacing with a plain switch, and that is work for a qualified electrician.
Wiring
Smart switches and the neutral conductor
A smart switch replaces the wall switch itself, so the fitting keeps ordinary bulbs and the switch keeps working normally for anyone who uses it. Usually the better long-term answer for a ceiling light, and there is one common blocker.
The neutral question
A traditional switch only interrupts the live conductor, so many older installations run only live wires to the switch box. A smart switch, like a smart bulb, needs continuous power for its radio, and that generally requires a neutral conductor present. Whether you have one depends largely on the age of the wiring and local practice.
This is mains electrical work. In many countries there are legal restrictions on who may carry it out in a dwelling, and requirements to certify it afterwards. This page describes what is involved so you can decide whether to pursue it. The work itself belongs with a qualified electrician, and in a rented home it wants the landlord's agreement first.
Two-way switching
Where one light is controlled from two positions, such as a stairway or a hallway, the wiring is more involved. Smart switches designed for it exist, and sometimes need a companion unit at the second position. Worth establishing before buying if it applies, because an ordinary smart switch fitted into such a circuit generally will not behave correctly.
Safety
Smart plugs, and what not to plug in
Smart plugs are the easiest entry point here. They sit between a socket and an appliance, need no wiring, and make anything schedulable. There is one genuine safety consideration that gets skipped constantly.
Check the load rating before plugging in anything that heats. Every plug states a maximum current or wattage. High-draw appliances such as heaters, kettles, tumble dryers and hair dryers can exceed it. Running an appliance beyond a plug's rating can overheat it, and that is a genuine fire risk rather than a theoretical one. Never run one through an extension lead or a daisy-chained adapter.
Good candidates
- Floor and table lamps, particularly awkwardly placed ones.
- Fans, humidifiers and dehumidifiers.
- Decorative and seasonal lighting.
- Low-draw morning appliances such as a coffee machine.
- Anything worth switching off automatically overnight or while away.
Poor candidates
- Anything that must not lose power unexpectedly. Fridges and freezers, medical equipment, aquarium pumps and heaters, and the network equipment everything else depends on.
- High-draw heating appliances, unless the plug is explicitly rated for that load.
- Appliances needing a manual restart after a power interruption, since cutting power simply leaves them off.
- Anything outdoors, unless the plug is specifically rated for outdoor use.
An honest look
What energy monitoring actually tells you
Many plugs now report how much power the attached device draws. This is genuinely interesting, and worth being realistic about.
What it does well
- Finding surprises. Discovering that something draws far more than assumed, such as an old second fridge in a garage or a games console in a high-power standby mode. You generally cannot guess these; measuring finds them.
- Settling arguments with numbers. Whether it is cheaper to leave something on or switch it off becomes answerable rather than debatable.
- Making consumption visible, which tends to change behaviour on its own.
Where the savings mostly are not
Standby draw is the headline reason these are marketed for saving money, and the reality is less dramatic than the pitch. Efficiency rules in many markets have pushed standby consumption of new electronics down substantially. A phone charger left plugged in draws a genuinely negligible amount, and switching it off through a plug that itself draws power continuously may save nothing at all.
A reasonable approach is to use one monitoring plug as a diagnostic tool rather than buying a dozen. Move it around, leave it on each appliance for a few days, and note what turns up. Once you know which two or three things actually matter, act on those specifically.
Treat the numbers as relative. Consumer monitoring plugs are useful for comparison and for spotting outliers. They are not calibrated instruments, and readings drift, particularly at very low loads.
Frequently encountered
Common situations, and what usually causes them
- A bulb has disappeared from the application. The wall switch, nearly always. Worth confirming it is on before assuming anything has failed.
- Bulbs flicker or buzz. Commonly an existing dimmer left in circuit, or a non-dimmable bulb on a dimmer. Also worth checking whether the fitting's total load falls below a dimmer's minimum.
- Lights come on at full brightness after a power cut. Most bulbs default to on when power returns, deliberately, so a light still works if its clever features fail. Many applications allow that default to be changed.
- Devices drop off as more are added. A house full of Wi-Fi bulbs and plugs can approach the device limit of a consumer router. Hub-based systems using a mesh protocol scale better.
- A plug is warm to the touch. Some warmth is normal. Noticeably hot means the load is likely too high, and the appliance's draw wants checking against the plug's rating.
- A routine fires but one device is missed. Often a timing matter, where a device has not responded before the routine moves on. Some platforms allow a short delay between steps.
Where a situation persists beyond these, the manufacturer holds model-specific information and the warranty. Anything involving fixed wiring belongs with a qualified electrician.
Keep reading
Lighting is where most people start
A single bulb costs very little and needs no wiring, which makes it the cheapest way to find out whether any of this suits you.
Read the speaker guideHow we checked this
Where this comes from
- The literature each manufacturer issues for its own equipment, which is where intended behaviour is set down
- What Apple and Google publish for people building software, since that is where handset permissions and radio handling are described
- The wireless specifications themselves, which govern how each band and every low-power protocol actually conducts itself
- Opening the applications and observing them in whatever state they are in today, with every check dated
Nothing stated here rests on a forum thread or an article with no name attached to it. Where a point simply cannot be pinned down, the page admits as much instead of papering over it.
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