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.
Bell GLS Filament Bulb - 4W ES
Bell 4W ES GLS filament bulb
Crompton PAR30 Reflector LED Light Bulb - E27 9.5W (100W Eqv) Warm White
9.5W LED PAR30 reflector, E27, warm white, dimmable, IP65, 100W equivalent
Allelectrics ES GLS Light Bulb - 11W Warm White
11W ES (E27) GLS bulb with warm white light output
Budget Bulb - 160W 117mm length
160W budget bulb, 117mm length, warm white 2700K
Wessex LED GU10 Glass Bulbs - 2W Cool White 230lm 5 Pack
5-pack of 2W cool white GU10 LED glass bulbs, 230lm
Crompton Candle LED Light Bulb Dimmable B22 5W (40W Eqv) - Cool White 10-Pack Cl…
Clear dimmable 5W LED candle bulb, B22, cool white, 10-pack
Energizer LED Capsule Bulb - G9 1.8W 200lm Daylight 6500K
1.8W G9 LED capsule bulb, 200lm daylight 6500K non-dimmable
Energizer GU10 Spotlight LED Bulb - 4.2W 345lm Cool White 4000K 4 Pack
4.2W GU10 LED spotlight bulb, 345 lumens, cool white 4000K, 4-pack
Crompton Lamps 7130 LED Lamp Candle - 5W 2700K
5W dimmable LED filament candle lamp, 2700K warm white, clear.
Status LED Filament GLS - 4W B22 Warm White
4W LED filament GLS bulb, warm white, B22 cap, 470lm
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.














