LED strip power supplies: which driver to buy and why it matters

Three types of power supply to choose between

A basic transformer, sometimes sold as an LED driver, does one job: it converts 230 V mains to a steady 12 V or 24 V output and nothing else. It is the cheapest option and fine for a strip that is simply switched on and off, such as under a kitchen cabinet with no dimming plan.

A dimmable driver adds circuitry that responds to a separate dimmer switch or a smart controller, letting you fade the strip rather than just switch it. These cost more and need a compatible dimmer to work properly — mixing a non-dimmable driver with a dimmer switch is a common cause of buzzing or a strip that only half-dims.

A CV/CC (constant voltage or constant current) driver is a more technical distinction that mostly matters for the type of strip you bought. Almost all strip lighting sold for home use is constant voltage, run at 12 V or 24 V, so this is worth checking on the strip's own packaging rather than treated as a third product to choose.

Matching wattage to the length of the strip

Every LED strip states its power draw per metre, typically somewhere between 4.8 W and 14.4 W per metre depending on brightness and density. Multiply that figure by the total length you are installing to get the strip's total wattage — a 5-metre run of a 9.6 W/m strip draws 48 W.

The power supply then needs headroom above that figure, not an exact match. A driver run at its rated maximum runs hot continuously, which shortens its life and is a common reason a supply that seemed adequate on paper fails within a year. Sizing the driver at around 80% load — so roughly 60 W for that 48 W strip — gives it room to run cool.

If a single run is long or you are lighting several rooms from one supply, it is often better to split the load across two smaller drivers than to push one large one to its limit, and it also means one failure does not take out every light in the flat.

Why a cheap driver flickers or fails early

Unbranded drivers sold very cheaply online often deliver less than their stated wattage, run without proper voltage regulation, and lack the capacitors that smooth out mains ripple. The visible result is flicker, particularly noticeable on camera or to sensitive eyes, and a hum that gets worse with age.

The less visible result is heat. A driver working harder than its components are rated for degrades faster, and in an enclosed space such as a kitchen cabinet with no airflow, that ageing speeds up. It usually fails outright rather than gradually, often within the first year or two.

This is where the money saved on a budget driver tends to disappear again, once you have bought a second one and spent an evening pulling a strip out from under a cabinet to swap it.

What to check before buying a driver

A handful of details on the packaging or spec sheet tell you whether a driver is worth buying, and they take a minute to check in the shop or the online listing.

None of this requires expert knowledge — it is the same kind of label-reading you would do for any appliance, just worth doing before rather than after installation.

• Rated wattage with headroom above your calculated total load
• Correct output voltage matching the strip: 12 V or 24 V, not assumed
• IP rating suited to the location — a bathroom or outdoor cove needs a sealed, moisture-rated driver, not a standard indoor one
• Dimmable marking if you plan to fit a dimmer, matched to that dimmer's type
• A case with ventilation slots if it will sit somewhere enclosed
• A visible safety mark rather than no marking at all

Where DIY ends and wiring work is worth having checked

Plugging a strip into a driver that is itself plugged into a wall socket is straightforward and well within a confident DIY job — sticking the strip down, connecting the low-voltage clips or solder joints, and running the cable neatly along a cove or under a cabinet lip.

It changes once the driver needs wiring into the mains supply directly, rather than through a plug — for instance feeding several drivers from one switched circuit, or fitting a permanent cove light as part of a renovation. That is 230 V work, and it should be done by a qualified electrician, connected properly to a fused and switched circuit rather than spliced into an existing cable.

If you are unsure which side of that line your job falls on, it usually comes down to whether anything gets wired into a junction box or consumer unit rather than a plug. Electrical work of this kind starts from 49 € per hour, and for a straightforward fitting job, light fitting installation starts from 40 € per job.

The driver we would fit in a typical Tallinn home

For most kitchen or living room strip installations in a standard Tallinn flat, a mid-range 24 V constant-voltage driver sized to around 80% load, with an IP20 rating for a dry indoor space, covers the job without overspending. If dimming matters, buying the dimmer and driver as a matched pair from the same range avoids the compatibility problems that cause buzzing.

In a bathroom, a wet room, or an outdoor cove above a terrace, the same logic applies but with an IP44 or higher sealed driver, kept somewhere it can still get air rather than wrapped tightly against a wall.

Where the job is a plug-in strip under one cabinet, doing it yourself with a reasonable driver is a sensible way to spend an evening. Where it becomes a permanently wired installation across a kitchen or a whole ceiling cove, having it wired in properly is worth the call-out, and it comes with 24 months' guarantee on the work itself.