Smart Christmas Lights: Schedules, Groups and Power Costs

Christmas lighting has one feature that sets it apart from the living room lamp: it is meant to be seen mainly from outside, and it often hangs in places nobody passes by to switch it off. The socket is behind the sofa, on the balcony or in the garage. Many people know the result: the lights burn until morning because nobody remembered them in the evening. The German Environment Agency (Umweltbundesamt) recommends switching Christmas lights off when nobody is home, in bright daylight and at night, especially when they also light up other people’s sleeping areas, and names the timer switch as a convenient way to do this (Umweltbundesamt).

Many households already have the tools for this. 38 percent of people aged 16 and over in Germany use smart lamps or light fixtures, and 35 percent use smart plugs (Bitkom). A plug that switches the floor lamp during the rest of the year can take over the string lights in Advent. Compared with a mechanical timer, it has three advantages: it follows the sunset instead of a fixed clock time, it can be combined with other plugs into groups, and it can be switched outside the schedule with a button, an app or a voice command.

The order matters. First comes the question of which lights should be on at all and when anyone sees them. Then the devices that suit the socket and the location. Only after that comes the schedule. Working in this order usually means fewer devices than you first expect, and lighting that runs on its own from the first Sunday of Advent to early January.

For most string lights, a smart plug is enough. It sits between the wall socket and the string’s plug and switches the power on and off. For this to work, the string has to light up by itself once power returns. Strings with their own controller for flashing and dimming programs sometimes start in the first program after a power interruption, or stay off. Test this before hanging them up: pull the plug, plug it back in and watch which mode the string starts in. Also check the maximum load printed on the smart plug. LED strings are far below it, but if you connect several strings to one plug, add up their wattages.

Outdoors, stricter rules apply. For all string lights used outside, the transformer and cable must be protected against splashing water, otherwise rain can cause a short circuit; as markings, the Verbraucherzentrale names the codes IP44, IP54 or IP64 or the symbol of a drop in a triangle (Verbraucherzentrale). String lights made for living spaces do not belong outdoors (Verbraucherzentrale). The same applies to the smart plug: if it carries no note about outdoor use, it is an indoor device. If there is no suitable outdoor socket, have a qualified electrician install one. An extension cord through a tilted window is not a solution, because the window can crush the cable.

For the color of the light, check the packaging. Lamps with less than 3,000 kelvin give warm white, yellowish light (Verbraucherzentrale), which comes closest to candlelight. If you mix strings from different makers, you can easily end up with a warm white window and a cool blue hedge. If devices from different brands are to work together in one app, a shared wireless standard helps; what the Matter standard can do here and where it reaches its limits is covered in the article Matter explained.

As soon as more than two strings are involved, it pays to think in zones rather than devices. A zone is an area that should switch on and off together: the windows facing the street, the garden with hedge and tree, the front entrance. In the app, combine the plugs of each zone into a group and give it a clear name. The schedule is then attached to the group, not to the individual plug. If a string is added, put it into the group and it takes over the schedule.

The front entrance is a special case. There, a safe path to the door counts as much as the atmosphere. A string or lamp that switches on with motion lights up exactly when someone arrives and saves power the rest of the time. How motion-activated light makes the way safer at night is described in the article Getting up safely at night. If you go away over the holidays, leave the string lights off; instead, the same devices can run an away schedule that turns on a room lamp in the evening. How such light schedules help against burglary is covered in Burglary protection for renters.

According to the Verbraucherzentrale, Christmas decorations with serious safety defects keep reaching the market (Verbraucherzentrale). It advises against relying on the CE mark alone, with which manufacturers merely declare on their own that they comply with the applicable EU directives; better indications are the GS mark for tested safety, a VDE test mark or a TÜV seal (Verbraucherzentrale). Old strings with incandescent bulbs also get hot: some incandescent bulbs reach up to 70 degrees Celsius, enough to set fir branches, straw stars or cloths alight, while LED strings give off much less heat (BAuA 2013).

A common mistake happens when connecting the lights. Plugging several power strips into one another increases the fire risk, because every plug connection heats up; if the strips are covered, for example under a rug or behind a curtain, the risk rises further (BAuA 2013). The combined wattage of all connected devices must not exceed the permitted rating of the power strip (BAuA 2013). A smart plug does not change this: it goes straight into the wall socket, and the string hangs on it, not on a chain of adapters.

When the string lights come down in early January, it is worth pausing the schedules rather than deleting them. Next November you switch them back on with one tap, and the groups and names are still there. Many smart plugs also measure consumption. Compare the measured value with your estimate: if it is clearly higher, a string is running longer than planned or uses more power than stated.

Smart technology can change how people use electricity: in almost 6 out of 10 households with smart home technology, 58 percent, users report that their electricity and energy consumption has fallen, and 44 percent of users say the technology motivates them to use electricity more consciously (Bitkom). For the rest of the year, the smart plugs from the Christmas lights can switch floor lamps on a schedule or cut devices in standby off from the mains. Which smart helpers do the most for heating and electricity costs is shown in Smart home 2026: lower heating and power costs.