Technical
LED mirror power supply and driver selection: a buyer's guide
2026-10-21 · 7 min read
The LED strip is the visible part. The power supply is the part that decides whether your product is still working in three years — and it is the part that appears in almost no specification. Here is how to specify it properly.
On most LED mirror orders, the electrical components are chosen by the factory and accepted without discussion. That is usually fine for a one-off retail batch. It stops being fine the moment you have a hotel group ordering four hundred units across three sites and expecting them to be interchangeable in five years.
Why 12 V dominates the category
Almost every vanity mirror on the market runs its LED strip at 12 V DC. This is not a marketing choice, it is a safety and cost decision that follows from the physics.
LED strips are typically made from SMD LED beads with a forward voltage of about 3.0–3.4 V each. A 12 V strip puts three beads in series per channel, which gives a comfortable margin: the driver can supply 12 V and each bead still has headroom, so the strip is less sensitive to the voltage difference between the first and last bead in the run. Run 24 beads down a long edge instead and the far end of the strip is measurably dimmer than the near end, because of the voltage drop along the copper trace.
The other reason 12 V wins is safety. Below 50 V DC is generally treated as a safe extra-low voltage in most electrical codes, which means the strip itself needs no earthing and no segregation from the user. It also means the failure mode is benign. On a 24 V or 48 V system, a damaged or moisture-affected strip can present a far more serious hazard in a bathroom.
For our mirror range, unless a project specifically requires otherwise, the standard is 12 V DC with a constant-current driver.
Constant voltage vs constant current: the distinction that matters
This is the single most misunderstood specification in the whole industry, and it is worth understanding because it determines how your product fails.
Constant voltage
The driver outputs a fixed voltage and the strip takes what it takes. A 12 V, 24 W driver will happily push 24 W into a strip rated for 12 W, and that strip will simply get very hot and eventually fail. The protection against this is a fuse, and fuses are not precise.
Constant current
The driver regulates current, and the strip sets the voltage by its own characteristics. A driver rated 600 mA will deliver 600 mA regardless of how many beads are in the channel. If a channel is shorted, damaged or partly failed, the current stays constant and the driver either holds the voltage up or shuts down on its over-current protection. It does not cook the strip.
For a product that will be installed in bathrooms, shipped by sea, installed by a third-party electrician and used for years, constant current with a driver that has active over-current and over-temperature protection is the correct specification. It converts a potential total failure into a non-event.
When you ask a supplier for the driver specification, look for these four things in writing:
- Output type: constant current, with the current in mA stated
- Input range: the full AC input range, e.g. 100–240 V AC (not just “220 V”)
- Protection: over-current, over-voltage, short-circuit and over-temperature, and whether they are active (switching) or passive (a fuse)
- Compliance of the supply itself: the driver is a mains-powered component and it carries its own approval, separate from the finished mirror
Wattage: how to size it without over- or under-driving
Two rules of thumb, both useful:
- Size the driver 10–20% above the strip's total current draw. A driver running continuously at 100% of its rating runs hot and shortens its own life. Headroom is cheap insurance.
- Never under-size. An under-sized driver runs at its limit or cycles on its protection, which produces visible flicker and a shortened service life for both the driver and the strip.
In practice, for a 600×800 mm mirror with perimeter LED lighting, a 12 V, 12–18 W supply is typical. Larger formats with more lighting surface, or an RGB colour-changing version with more channels, need proportionally more.
Colour temperature, CRI and the binning question
- CRI. For a mirror, specify CRI 90 minimum. This is where the difference between a 12 W mirror that costs USD 6 and one that costs USD 9 is usually spent. Below CRI 90 the light makes skin tones look flat and slightly green — and this is the one place on the product where the user's own face is the test.
- Colour temperature consistency. Ask how the LEDs are binned. Binning means sorting the LED beads by their actual colour characteristics so that all the strips in a batch match. Unbinned beads from the same reel can visibly differ from strip to strip — and on a large mirror with a continuous run of light, a colour shift along the run is obvious.
- Single bin or mixed? A single bin (all LEDs from the same colour bin) is the consistent choice. Specify it if the project has multiple mirrors in the same room that must match.
Dimming: the four methods and which to specify
- Touch dimmer on the mirror face. The most requested configuration for hotel work. A capacitive touch sensor behind the glass or on the frame, with typically three positions: 3000 K / 4000 K / 6000 K, or off / low / full. Specify whether the touch area is visible to the user or hidden behind the frame.
- Push-button or rocker on the wall. Cheapest to build, and the cheapest to look. Suitable for a commercial washroom where the mirror is not the point.
- PIR / occupancy sensor. The mirror lights when someone approaches. Popular in hotel corridors and public washrooms, and it reduces the operating cost of a large estate. Needs a sensor with a suitable detection angle and a defined timeout.
- Dimmable by a room control system (DALI, 0–10 V, PWM or Tuya-type).strong> This is the one that has to be decided at order stage, because it determines the driver you buy. A driver that is not dimmable by the building's protocol cannot be made dimmable later — it means a different driver, a different wiring plan and a different sample.
Whatever the method, specify the flicker performance. Cheap drivers pulse at 100 Hz and, under a camera, produce a visible strobe effect. In a hotel bathroom mirror this is picked up on every video call and every photograph. Ask for the driver’s flicker rating; anything under a few percent flicker is not acceptable for a mirror.
IP rating and where the driver physically sits
The rating on a mirror is only as good as the component that determines it. Two arrangements:
- Driver inside the mirror housing. Fully sealed, protected, and the mirror is a single self-contained unit. This is what we do for bathroom wall mirrors: the driver sits in a sealed compartment at the top of the housing, potted against moisture ingress, and the unit is tested as a whole.
- Driver outside the mirror. The mirror takes 12 V DC and the adapter is separate. Advantageous for a bedroom vanity where the mirror is in a dry area; for a bathroom it means a service item in a wet zone, which is why we do not specify it there.
Ask where the driver is, what its IP rating is in isolation, and whether the whole assembled mirror has been tested or only the components. These are different claims and only one of them is worth anything to you.
Six failure modes we have seen in the field
- Colour banding along a long run. Unbinned LEDs, or a driver whose output is not tightly regulated. Fix at the design stage: binned LEDs, a regulated driver, and where possible splitting a long run into two shorter parallel channels.
- Flicker on camera. A driver with poor ripple and no PFC. It looks fine to the eye and ruins every photograph and video call. Always ask about flicker specifically.
- Early driver death in a humid environment. A driver that is not properly potted or sealed, sitting inside a housing that gets warm and damp. The single most common cause of a whole-batch failure we are asked to investigate.
- Touch sensor that stops responding. Usually moisture ingress into the sensor area, or a sensor with no sealing gasket around the glass. Specify the sensor's IP rating and the gasket detail on the drawing.
- Hot spots and uneven light. A strip mounted directly against the aluminium frame with no diffuser produces a visible bright line. Specify the light guide or diffuser geometry — this is a design decision, not a purchasing one.
- Nothing fails, but the mirror looks wrong. The strip is visible in the reflection, or the colour temperature is inconsistent with the room's other lighting. Fixable at sample stage only.
What to put on the specification
- Input: 100–240 V AC, 50/60 Hz
- Output: 12 V DC constant current, 600 mA, with active over-current, short-circuit and over-temperature protection
- Driver power: 15 W for a 600 ×800 mm perimeter-lit mirror (headroom over the strip draw)
- LED: SMD 2835, 12 V, 3000 K, CRI 90+, single colour bin, 120 LEDs/m
- Dimming: capacitive touch on the mirror face, 3 positions (3000/4000/6000 K), IP-rated sensor
- Flicker: no visible stroboscopic effect on camera
- Protection class: Class II, double insulated, no earth required (where the local code permits)
- Driver location: inside the mirror housing, sealed compartment, potted against moisture
- Certification: driver and finished product approvals for the destination market stated separately
Two things worth asking a supplier that most will not volunteer
First: “Can you send me the driver model and its datasheet?” A factory that has a documented driver specification will send it. One that changes the driver between batches cannot, and neither can you. Second: “What is your replacement policy if a unit fails in service?” The answer tells you whether a batch from three years ago can be matched to a batch today, and whether the spare parts will exist.