Energizer LED GLS Bulb E27 4.2W Opal Non-Dimmable - Daylight 6500K

A 4.2W LED GLS bulb with an E27 screw cap, the rounded pear shape most people picture when they think of a household light bulb. Energizer rate it at 470 lumens with a colour temperature of 6500K, which is daylight white: a crisp, slightly blue cast rather than the yellow glow of an old filament lamp. The retail pack marks it as a 40W replacement, so it stands in for an older 40W incandescent while drawing a little over four watts. The same pack prints a 15,000 hour lifespan, and the energy rating is E.

E27 is the larger of the two common screw caps used in the UK, measuring roughly 27mm across the threaded metal base; if the old bulb's thread is noticeably narrower it is an E14 and this one will not fit. Daylight at 6500K is a working light. It suits a garage, a workshop, a utility room, a home office or a craft table, anywhere you want colours to read true and small detail to stay sharp. In a bedroom or a sitting room most people find it too cold and reach for warm white instead, so match the room to the number before you buy.

The pack marks this bulb non dimmable, so it needs a plain on and off switch. On a dimmer circuit an LED built without dimming control can flicker, buzz or fail early, even at full brightness, so if your fitting runs from a dimmer, choose a dimmable bulb instead. Each box holds one bulb, and these are sold in multiples of twelve, which makes twelve boxes the smallest order we can take: sensible if you are relamping a workshop or keeping spares on a shelf. It sits alongside our wider range of Energizer LED bulbs in GU10, B15 (SBC) candle and 2G11 PLL types.

How do I check that my fitting takes an E27 cap?

Take the old bulb out and look at the base. E27 is a screw thread about 27mm across; the narrower screw cap is E14, and a bayonet base with two side pins is B22 or B15. Only a 27mm screw thread will take this bulb.

How bright is 470 lumens in practice?

It is the brightness people associate with an old 40W incandescent, which the pack confirms as the replacement figure. Comfortable for a bedside lamp, a small pendant or a hallway fitting, but on the modest side for lighting a whole living room from one shade.

Can I use it with a dimmer switch?

No. The pack marks this bulb non dimmable, so it is made for a standard on and off switch. Run on a dimmer it may flicker, hum or fail early, so pick a bulb marked dimmable if your circuit has one.

What does 6500K daylight look like next to warm white?

Much cooler and whiter. Warm white sits around 2700K to 3000K and reads yellow and soft; 6500K reads bright and slightly blue, which keeps colours honest for reading, sewing, DIY and detailed work.

Is an IP rating given for this bulb?

No. Neither the specification nor the retail pack prints an IP figure, so we state none and make no protection claim on Energizer's behalf. Treat it as an ordinary unrated lamp for dry, enclosed fittings.

How many bulbs will I receive?

One bulb per box. The listing is sold in multiples of twelve boxes, so the smallest order is twelve bulbs, which is useful when relamping several fittings at once.