Colour temperature explained: 2700K to 5000K

Colour temperature is measured in kelvin and describes the appearance of the light, not its brightness. Low numbers look warm and yellow; high numbers look cool and blue-white. It is the single specification most likely to generate a complaint after handover, because it is obvious to everyone and impossible to argue about.

The four numbers that matter

• 2700K — warm white. Closest to the old incandescent bulb. Yellow, relaxing, flattering to skin and wood. Bedrooms, living rooms, dining rooms, hospitality.
• 3000K — soft white. Still warm but noticeably cleaner. The default for most Canadian residential work, and the safest single choice for a whole house.
• 4000K — neutral or cool white. Crisp and neutral, no obvious colour cast. Kitchens, bathrooms, laundry, garages, offices, retail.
• 5000K — daylight. Bright and blue-leaning. Workshops, warehouses, task areas, security lighting. In a living room it reads as clinical.

Choosing by room

A defensible default for a residential job is 3000K throughout the living areas, 4000K in kitchens, bathrooms and the garage. If the client wants a single temperature everywhere, 3000K upsets the fewest people.

For commercial and industrial work the logic reverses: 4000K is the baseline, and 5000K goes where the task demands contrast — warehouse aisles, mechanical rooms, inspection areas. Our UFO high bays are typically specified at 4000K or 5000K for this reason.

Consistency beats correctness

A room lit at a consistent 4000K looks deliberate. A room with one 3000K fixture among five at 4000K looks broken, and it is the first thing anyone notices. This matters most when you are replacing a failed fixture years later, or finishing a job someone else started.

Two practical habits: record the colour temperature in the panel schedule or the closeout package, and order the whole room from one production batch where you can. Even within a single specification, manufacturers allow a tolerance, and two batches can differ slightly.

What 5CCT selectable actually means

Most of our slim panels ship as 5CCT — a switch on the fixture selects 2700K, 3000K, 3500K, 4000K or 5000K. It is not a colour-changing light. You set it once at installation and it stays there.

What that buys you is inventory and decisions. One part number covers every room in the house, you can hold fewer SKUs on the truck, and you can change your mind on site when the client sees the paint colour under the light. The Votatec 9W 4-inch 5CCT panel and the Liteline SLM4 5CCT downlight both work this way.

The one discipline it demands: set every fixture in a room before you close the ceiling. A switch left on the factory default among a room of 3000K fixtures is a callback.

What about CRI?

Colour temperature is not colour quality. CRI, the colour rendering index, describes how accurately a light source shows colour, on a scale to 100. Anything at 80 or above is acceptable for general use; 90-plus is worth specifying where colour judgement matters — retail displays, kitchens, bathrooms with mirrors, anywhere someone is choosing paint or matching a finish. Two fixtures can share 3000K and render colour very differently.

What to order

Browse selectable-temperature fixtures in LED slim panel lights and recessed lighting. Every collection page filters by colour temperature, so you can narrow to a fixed 3000K or to 5CCT selectable directly.