The one part of a lighting installation nobody sees, and the first one to ruin it when it is chosen badly.
LED strips and most profiles run on constant voltage, usually 12V or 24V. Spots, panels and most professional fixtures run on constant current, expressed in milliamps. Both are called a "transformer" in everyday speech, but they are not interchangeable: the wrong one either lights nothing or burns the fixture.
The driver is sized on the total load plus about twenty per cent. A driver running permanently at its limit runs hot, and heat is the number one reason drivers fail. The headroom also covers the fixture that gets added later — and one always does.
A non-dimmable driver does not become dimmable later. And a dimmable one mismatched to the switch will flicker or cut out before the light truly dims. TRIAC works with wall dimmers and is the usual answer in homes. 0-10V and DALI are used in projects with scenes, zones and central control. The choice is made together with the electrical design.
Somewhere reachable without opening the ceiling. A driver sealed permanently into plasterboard means that when it fails — and it will fail before the LED does — the ceiling comes down. It belongs in an inspection box, a distribution board or above an accessible ceiling, with ventilation. This is probably the cheapest and most ignored piece of advice in the whole installation.
Almost always because the driver and the dimmer are not matched, or because the load is below the dimmer’s minimum. It is solved by matching the pair, not by changing the fixtures.
Yes, provided their combined power plus headroom stays within capacity and both are the same voltage. But if they must switch separately, they need two circuits — and often two drivers.
A quality driver, sized with headroom and ventilated, lasts as long as the LED itself. An overloaded one, or one sealed in without air, can fail within two years.
Send us the plan or a few photos. We will tell you what the space needs — not what the catalogue happens to have.