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 Golf Bulb - 5.5W E27 Warm White
5.5W LED golf ball bulb, E27 warm white 470lm, non-dimmable, 40W equivalent
LED Reflector Lamp - R50 4.2W SES (E14) 470lm
4.2W R50 LED reflector lamp with SES (E14) cap, 470lm warm white, non-dimmable.
Supacell LED C37 Bulb - 3W 280 Lumen 2700K
3W LED C37 bulb, 280 lumens, warm white (2700K), non-dimmable
L.E.T. FCT5 2D 4-Pin Circular CFL Fluorescent Bulb - 55W 865
55W 2D circular CFL bulb, 6500K daylight, 4-pin GR10q
Ener-J Smart WiFi GU10 LED Spotlight Bulb - 5W
Smart 5W GU10 LED spotlight bulb, colour-changing, works with Alexa and Google
Integral PAR16 LED Bulb - 7W E14/SES Warm White
7W PAR16 LED bulb, E14 SES, warm white 3000K, 500 lumens
Bell Dimmable LED GU10 - 5W 3000K
Dimmable 5W LED GU10 lamp, 3000K colour temperature
L.E.T. T9 2D 4-Pin Circular CFL Fluorescent Bulb - 32W 830
32W warm white circular CFL bulb with GR10q 4-pin base
Crompton Lamps 15W Pygmy B22 Dimmable - Red
15W dimmable red pygmy B22 light bulb for decorative use
LED 4W Striplight Lamp - 4W 221mm 330lm
LED striplight lamp, 4W, 330lm, warm white 3000K, S15 cap, 221mm length
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.














