B15 (SBC) LED Filament Golf Bulb 4W 470lm - Warm White 2700K

This is a golf ball shaped LED bulb with a B15 small bayonet cap, drawing 4W and giving 470 lumens of warm white light at 2700K. The glass is clear rather than opal, and four slim filament strands run up the centre of the bulb, so the light source itself is part of the look when the bulb sits in an open shade or a bare holder. The pack rates it at 10 years, or 10,000 hours, and puts its output level with a 40W conventional bulb.

B15 is the smaller of the two bayonet caps, 15mm across the pins rather than the 22mm of a standard B22, and it turns up on wall lights, small pendants, bedside lamps and multi-arm ceiling fittings where a slim cap keeps the holder discreet. Take the old bulb out before you order and measure the cap, since the two sizes look similar once they are up in the fitting but will not swap. The golf shape is short enough to sit inside a small shade without pushing at the fabric, and clear glass suits fittings where the bulb is on show.

The light is a warm 2700K, the yellow-leaning tone of an old filament bulb, which suits living rooms and bedrooms better than the brighter 4000K and 6500K versions. It is not dimmable, so wire it to a plain switch; on a dimmer circuit it may flicker or buzz. The beam is a broad 280 degrees, close to all-round light. The energy rating is E, each unit is one bulb, and the minimum order is 5, sold in multiples of 5. We stock other B15 bulbs beside it, including candle shapes and golf bulbs in cool white and daylight.

How do I know if I need B15 and not B22?

Pull the old bulb out and measure the metal cap across the two pins. B15 measures 15mm and B22 measures 22mm, and although the two push and twist in the same way, neither will seat in the other's holder.

Is 470 lumens bright enough to replace a 40W bulb?

Yes. The pack puts this 4W lamp level with a 40W conventional bulb, so it is a sensible swap for a bedside lamp, a wall light or one lamp in a multi-arm fitting.

Can I put it on a dimmer switch?

No. The specification gives it as non-dimmable, so it needs a plain on and off switch. On a dimmer it may flicker, buzz or refuse to strike at the bottom of the dial.

What does 2700K warm white actually look like?

It is the soft, slightly yellow light people remember from old filament bulbs. It flatters wood, warm paint colours and skin tones, and reads far cosier than a 4000K or 6500K lamp.

Why is the glass clear rather than frosted?

So the four filament strands show. That is the point of a filament lamp, and it works best in open shades, glass lanterns and bare holders where the bulb is meant to be seen.

Do I have to order more than one?

Each unit is a single bulb, and the minimum order on this listing is 5, sold in multiples of 5, so the smallest purchase is five bulbs.