Energizer 5.5W GU10 Dimmable LED Bulb - Cool White 4000K

The Energizer 5.5W GU10 is a dimmable LED spotlight bulb that replaces a 50W halogen equivalent while drawing only 5.5W. The bulb produces 350 lumens of cool white light at 4000K, with a 36° beam angle that focuses light downwards for task lighting, kitchen worktops, bathroom mirrors and directional accent lighting in recessed or surface-mounted GU10 fittings.

The GU10 base is a twist-and-lock fitting used across the UK in downlight housings, track lights and spotlight fittings. The bulb is fully dimmable when paired with a compatible LED dimmer switch, allowing brightness to be adjusted from full output down to approximately 10% depending on the dimmer model. The 4000K colour temperature sits between warm white (2700K-3000K) and daylight (5000K+), giving a neutral white light often described as 'cool white' that renders colours accurately without the yellow cast of warm white or the blue tint of daylight.

The bulb measures 50mm diameter by 54mm height, fitting standard GU10 downlight housings without protrusion. The rated lifespan is 15,000 hours at typical usage, which translates to approximately 15 years at 3 hours per day. The aluminium body and glass lens dissipate heat efficiently, preventing overheating in recessed ceiling fittings where airflow is restricted. The Energy Rating G reflects the efficiency of the LED chip relative to current EU standards introduced in 2021, which rate all bulbs on a tighter scale than the previous A-G labelling.

Is this bulb dimmable?

Yes. The bulb is fully dimmable when used with a compatible LED dimmer switch. Dimmer compatibility varies by manufacturer — trailing-edge dimmers typically perform better with LED bulbs than leading-edge models. If you experience flickering or a restricted dimming range, the dimmer switch may need replacing with an LED-rated model.

What's the difference between 4000K and warm white?

4000K is a neutral or cool white that appears crisper and whiter than warm white (2700K-3000K), which has a yellow tint. 4000K is often preferred in kitchens, bathrooms and workspaces where colour accuracy and alertness matter. Warm white is typically chosen for living rooms and bedrooms where a cosier, more relaxed atmosphere is wanted.

Will this fit my existing GU10 downlights?

Yes. The GU10 base is a standard UK twist-and-lock fitting used in recessed downlights, surface-mounted spotlights and track lighting. The 50mm diameter and 54mm height match the dimensions of a typical halogen GU10, so it will fit any housing designed for GU10 bulbs.

What does Energy Rating G mean?

The EU introduced a new energy labelling scale in 2021 that rates all bulbs from A (most efficient) to G (least efficient) on a much tighter scale than the old A++ to E system. Most LED bulbs now fall into categories F or G under the new scale, even though they remain far more efficient than the halogen bulbs they replace. This G-rated LED still uses 89% less energy than the 50W halogen it replaces.