Motion sensor night lights, and the number of seconds nobody prints

A sensor light is the cheapest good idea in a house: the cupboard lights up when you open it, the stair lights up when you step on it, and nobody has to find a switch. Twenty of them are on this page, and the titles are sure about where you should put them and quiet about everything that decides whether you will like it.

The three ways to power one, and what each costs you

Rechargeable, on seven titles. A cell inside, a USB socket on the side, and every few weeks the light comes off the wall to sit beside a charger. In a wardrobe that fires a few times a day, that is a charge every month or two. In a hallway that fires fifty times a night, it is a charge every week, and a light you have to keep taking down is a light that ends up in a drawer.

Battery, on three. AAAs, usually, which means nothing comes off the wall and the running cost is a packet of cells a year. Unfashionable and, for a stair, the right answer.

Plug-in, on four. Never charged, never changed, and stuck wherever the socket is. That is fine for a hallway with a low socket and useless for a stair or a cupboard. Three of the four say EU plug and none says UK, which is worth more than a sentence and gets one below.

One title, the step light, offers all three: USB, battery or EU plug. It is the only listing on this page that lets you decide after it arrives.

Which USB

Eight titles say USB. Two say Type-C. The other six leave you to find out whether the socket on the side is the one every cable in your house already fits or the older micro-USB that needs a cable kept specially for it. On a light you charge monthly, that is the difference between charging it and meaning to.

PIR, and what it can and cannot see

Four titles say PIR, and three say human body induction or infrared, which is the same sensor with the seller’s words on it.

A passive infrared sensor sees warmth moving across its field. It is good at a person walking past, poor at a person walking straight at it, and blind through glass. That geometry decides where it goes: side-on to the stair, not facing down it; inside the wardrobe pointing at the door, not at the clothes.

None of the twenty states a detection range or an angle. The usual figures are three to five metres and about a hundred degrees, and if a listing’s photographs give a number it is worth believing more than the absence of one.

The number nobody prints

After the last movement, a sensor light stays on for a fixed time and then goes off. That is the hold time, and it is the single spec that decides whether the light is a pleasure or an irritation. Fifteen seconds is too short for a stair. Thirty is about right for a hallway. Some lights let you choose; most do not.

Not one of these twenty titles gives it. Ask the seller for the number before you buy, and if they cannot say, assume the short one.

The second missing number is whether the light knows it is daytime. A light sensor alongside the motion sensor keeps it off in daylight, which on a battery light is most of the battery. Two titles say auto on and off, none says dusk to dawn, none gives a lux figure. In a windowless cupboard it does not matter. In a hallway with a window, it is the difference between a month and a week between charges.

Warm or white

Four titles say what colour the light is: white or warm on one, three colours on another, RGB on a cabinet bar sold for gaming, and one figure, 2,600 to 2,800K, on the plug-in. That last one is the colour of a candle, and for a light that comes on at three in the morning it is the right one.

A cold white sensor light in a bedroom is a small daily unkindness. If a title does not say warm, do not assume it. The clamp desk lamp guide covers what the kelvin figure means and why it is worth having on a title.

Magnetic, and the fixing that matches the power

Four titles say magnetic, one says drill-free, and the rest say nothing about how the light meets the wall.

For a rechargeable light the fixing matters more than it sounds, because the light has to come off to charge. A magnetic plate stays put and the bar pulls off and snaps back. A bar stuck straight on with adhesive gets peeled off monthly until the adhesive gives up, and then it lives on the shelf.

Three titles give a length, one metre to five for a strip, and 10 to 50cm for the bars. A strip is for the underside of a run of cupboards; a bar is for a single door or a step.

Three that are not night lights

A sensor switch. One title is a mains PIR module, 110 to 240 volts, that you wire between a supply and a lamp. It is a component for someone who is happy inside a light fitting, not a thing you stick to a wall.

A hand-sweep light. One cupboard light turns on when you wave a hand near it rather than when you walk past. That is a proximity sensor, not a motion sensor, and it is the better choice for a kitchen cupboard you open with your hands full, and the wrong one for a stair.

A fake camera. One title is a solar dummy security camera with a sensor light in it, sold to look like surveillance. It is on this page because the gateway files it as a night light. Whether you want a fake camera on your wall is a different question, and this guide is not the place for it.

What I would actually do

For most people, the rechargeable magnetic bar that says white or warm and is sold for stairs and hallways. Two titles here state fixing, power and colour together, and the other one’s colour is RGB for a gaming desk; this is the one for a house.

For a hallway with a low socket, the plug-in that gives a kelvin figure and dims. It says EU plug. Ask the seller for the UK version, and if there is not one, that adapter is the price of the only stated colour temperature on the page.

For a wardrobe, the bar that says Type-C. A wardrobe fires a sensor light so rarely that the charge lasts weeks, and when it does need the cable, it is the one you already have.

For a stair, the battery strip. It runs the length of the flight, it fires from the top or the bottom, and a packet of cells a year is the whole running cost. The step light that takes USB, batteries or a plug is the other honest answer, and the one to buy if you want to decide later.

Whichever you buy, ask one question first: how many seconds does it stay on. It is the number that decides everything and the one number no title here has written down.