5W GU10 Dimmable LED Bulb 4000K Cool White - 680lm

The Knightsbridge 5W GU10 LED bulb delivers 680 lumens of 4000K cool white light through a 40° beam angle, housed in a white polycarbonate body with a prismatic diffuser. The bulb runs on 230V mains and fits any standard GU10 twist-and-lock socket, replacing halogen GU10 bulbs in downlights, track lighting and spotlight fittings.

Designed for task lighting in kitchens, bathrooms, offices and retail display, the 4000K colour temperature sits between warm white and daylight, providing clear visibility for reading, food preparation and detail work without the yellow cast of 2700K bulbs. The 40° beam spreads light across a 1.2m diameter circle when the fitting is mounted at a typical 2.4m ceiling height, making it suitable for general room lighting when multiple bulbs are spaced evenly.

The bulb is dimmable with most trailing-edge and leading-edge dimmers, though compatibility varies by dimmer model — testing before full installation is recommended. At full brightness the 5W LED draws approximately one-tenth of the power of a 50W halogen GU10 while producing comparable light output. The rated L70B50 life of 25,000 hours translates to approximately 11 years of use at 6 hours per day before the bulb drops to 70% of its original output.

The prismatic diffuser softens the LED point sources and reduces glare when the bulb is visible in open fittings. The polycarbonate construction withstands the repeated thermal cycling of dimming and switching better than glass-bodied alternatives, and the compact 50mm diameter by 54mm height matches the form factor of most halogen GU10 bulbs.

Product Specification Sheet

Is this bulb dimmable?

Yes, the bulb is compatible with most trailing-edge and leading-edge dimmers. Dimmer compatibility varies by model, so it's advisable to test with your specific dimmer before installing multiple bulbs. Some older resistive dimmers designed for halogen may cause flickering at low levels.

What's the difference between 4000K and 3000K bulbs?

4000K produces cool white light with a neutral, slightly blue-toned appearance that enhances clarity and contrast, suited to task lighting in kitchens and offices. 3000K produces warm white light with a yellow-toned appearance closer to traditional incandescent bulbs, preferred for living rooms and bedrooms.

How long does the bulb last?

The rated L70B50 life is 25,000 hours, meaning the bulb should maintain at least 70% of its original 680 lumen output for approximately 11 years at 6 hours of use per day. Actual lifespan varies with dimming patterns and thermal conditions in the fitting.

Can this be used in bathroom downlights?

The bulb carries an IP20 rating, which provides no moisture protection. It can be used in bathroom downlights only if the fitting itself is rated IP44 or higher and the bulb sits inside a sealed housing that prevents direct exposure to moisture and steam.