When you’re choosing light bulbs, start with the fitting, the output you need, and whether the lamp is on a dimmer. GU10, E27, E14 and bayonet light bulbs all do the same job, but the wrong cap or a non-dimmable lamp bulb is where the call-backs start. LED light bulbs are usually the first swap for most replacements. Filament or decorative versions make more sense where the fitting is on show and the look matters.
Status LED R39 Reflector Light Bulb - E14 SES 4W Warm white
4W LED R39 reflector bulb, E14 SES cap, warm white light
Kosnic Filament GLS - 4.2W A60 E27 Clear 2700K
4.2W LED filament GLS bulb, E27, 2700K warm white, clear glass
Crompton Lamps LED GLS Thermal Plastic Lamp - 15W 2700K 1521lm B22d Non-dimmable
15W LED GLS lamp, 2700K warm white, 1521lm, B22 base, non-dimmable
Homeflow Decorative Filament LED Smart Bulb - Bayonet Cap Warm White
Warm white 5.5W smart filament bulb, B22 bayonet cap
Crompton Lamps LED R50 Reflector - 6W
6W LED R50 reflector lamp with thermal plastic body.
ALI Industries LED BA9 Bayonet - 10mm x 23mm White 110V 4 Chip
110V LED BA9 bayonet bulb, white light, long life, easy visual indication
Crompton Candle LED Light Bulb E27 4.2W (40W Eqv) Cool White - 10-Pack
10-pack 4.2W LED candle bulbs (E27, cool white) replacing 40W, 470 lumens, 15,00…
Integral LED GU10 Bulb Dimmable - 620lm 6W Cool Daylight
Dimmable 6W LED GU10 bulb, 620lm, cool daylight, long-life.
Crompton Lamps 15W Pygmy B22 Dimmable - Green
15W green pygmy incandescent bulb, B22 cap, dimmable
Eveready Light Bulb Capsule - 12V 10W 2 Pack
Eveready capsule light bulb, 12V 10W, 2 pack
Start with the space you’ve got and how the lamp will be used, then narrow the light bulbs from there. A tight fitting or shallow shade rules out some shapes straight away. A dimmer changes the choice again, because not every lamp bulb behaves well at low output. Most call-backs come from the wrong cap or a bulb that looks right on paper but sits awkwardly in the fitting. If you’re replacing like for like, keep the cap and size consistent first, then decide whether you want a standard LED, a dimmable option, or a more decorative finish.
For most jobs, you narrow light bulbs by format before anything else. LED light bulbs are the usual pick when you want lower running cost and less heat, but the lamp still has to suit the bulb, and any dimming gear needs checking.
Bayonet light bulbs still make sense when you’re swapping like for like and want the same cap back in without changing the holder. Screw light bulbs, including e27 light bulbs and e14 light bulbs, cover the same sort of replacement work. E27 suits larger general-purpose fittings. E14 is more common in smaller decorative lamps. GU10 light bulbs are the one you reach for when the fitting takes a mains spotlight lamp, though the wrong type is less forgiving once it’s in hand.
The first check is the fitting and the lamp body around it. That tells you if you’re buying a straight replacement or changing the look of the job.
After that, check whether it needs to dim cleanly and whether LED light bulbs make sense for the running cost. A cheap swap that flickers on a dimmer gets called back.
Shape matters too. A shallow shade or tight lantern usually rules out the bulkier options. Decorative lamp bulbs are picked more for the finish than the output.
If the job is moving away from lamps altogether, Downlights are the next call. If you only need the light to come on when someone’s there, Motion Sensors may be the better buy.
Once you’ve settled the bulb spec, the next call is usually the gear around it - the fitting, any trim or screen, and whether the lamp needs a matching control or sensor. That keeps a simple replacement from turning into a second visit.
A lot of call-backs come from mixing the wrong bulb with the wrong fitting, or leaving the control side unresolved. If the job includes downlights or a timed circuit, sort those parts with the light bulbs so you’re not back chasing compatibility after the fact.














