How to Choose the Right Bulb Base for Your Ceiling Kit

Quick answer

Check the ceiling kit or pendant you already own first: most Tom Raffield wooden ceiling lights are supplied with a white and brass ceiling kit built around an E27 holder. If you are buying a standalone kit, choose the holder size that matches your existing flex and ceiling rose, then match the bulb base, wattage and dimming to that holder.

Choosing the right bulb base is less about the bulb you like and more about the holder you already have. Get that order right and the rest of the decision — shape, brightness, dimming — becomes straightforward rather than a guessing game.

This guide walks through the same checks we would run before pairing a bulb with a wooden ceiling light, from reading the holder to confirming dimmer compatibility. It uses the White & Brass Ceiling Kit E27, the Crompton 12677 LED G95 Globe Light Bulb and the Tala Gaia 6W LED Filament Light Bulb as worked examples.

Start with the holder, not the bulb

Every bulb base decision begins at the lamp holder inside the ceiling kit or pendant. Look at the threaded or pinned opening: a wide screw thread is an Edison screw holder, while a pair of offset pins is a bayonet holder. The size code follows from there, and it is fixed — you cannot adapt a B22 holder to take an E27 bulb without changing the holder itself.

If your light already came with a kit, the holder type is set. Tom Raffield supplies a white and brass ceiling kit as standard with most wooden ceiling lights, and that kit uses an E27 holder. That single fact narrows your bulb search immediately and stops you buying a base that will not physically fit.

• Checkpoint: photograph the holder opening before you shop, so you can compare it with the bulb base diagram.

Decode the base codes: E27, B22 and the numbers in between

The letter tells you the fitting style and the number tells you the diameter in millimetres. E stands for Edison screw, B stands for bayonet cap. So E27 is a 27mm screw base, E14 is a 14mm screw base, B22 is a 22mm bayonet base and B15 is a 15mm bayonet base. E27 and B22 are the two common full-size mains bases in the UK and Europe.

The practical difference between E27 and B22 is the locking method, not the light output. E27 screws in and tightens progressively; B22 pushes in and twists to lock with spring-loaded pins. Both accept dimmable LED bulbs, and both are available in the same wattages and colour temperatures, so the choice is usually made for you by the holder.

• Common mistake: assuming a small screw base (E14) is interchangeable with a small bayonet base (B15). They are not.

Measure the holder if the code is not printed

Older or unbranded fittings often have no label. Measure the internal diameter of the holder across the widest point of the opening with a ruler or calipers. Roughly 27mm points to E27, roughly 22mm to B22, roughly 14mm to E14 and roughly 15mm to B15. A measurement within a millimetre is usually enough to separate the two full-size options.

If the holder is recessed inside a wooden shade, measure from below with the light switched off and the circuit isolated at the consumer unit. Do not force a bulb into a holder to test the fit; a cross-threaded E27 base or a bent B22 pin can damage both the bulb and the fitting.

• Checkpoint: if the measurement sits between sizes, take the holder to a hardware store and compare it with a known bulb base.

Match bulb shape and brightness to the shade

Once the base is confirmed, the shade decides the shape. A globe bulb suits an open shade where the bulb is meant to be seen, while a smaller or partially concealed bulb suits a shade that hides the luminaire. The Crompton 12677 LED G95 Globe Light Bulb is a dimmable opal glass globe rated at 806 lumens, roughly a 60W incandescent equivalent, which makes it a sensible choice for darker rooms that need task lighting.

Where the shade conceals the bulb but you still want a bright, warm output, an opal or coated bulb controls the glare that a bare filament can throw. The Tala Porcelain II 6W LED Light Bulb uses a phosphor coating for exactly that reason, giving a comfortable ambient white light rather than a sharp point source.

• Common mistake: choosing a bulb by wattage alone. Lumens tell you brightness; watts tell you energy use.

Confirm dimming and control compatibility

If your ceiling kit is on a dimmer, the bulb must be dimmable and the dimmer must be compatible with LED loads. A dimmable bulb on a non-dimmable circuit will either not dim or will flicker; a non-dimmable bulb on a dimmer can buzz and fail early. Check the bulb packaging for a dimmable rating and check the dimmer for a minimum LED load figure.

The White & Brass Ceiling Kit E27 includes two metres of adjustable, dimmable off-white corded flex, which means the flex itself will not be the limiting factor in a dimming setup. The bulb and the wall dimmer are the two parts that must agree.

• Checkpoint: test one bulb on the dimmer across its full range before buying a full set.

Buy the kit and bulb together when starting fresh

If you are building a new fitting rather than replacing a bulb, buy the ceiling kit first and let it set the base. A standalone kit gives you the holder, flex and ceiling rose in one purchase, so there is no mismatch to resolve later. The White & Brass Ceiling Kit E27 pairs reflective brass details with a matte white ceiling rose and two metres of adjustable, dimmable corded flex.

If your light is a chandelier rather than a single pendant, check whether it takes a specific add-on bulb set before ordering singles. The 5* Tala Globe Light Bulb - Add On is supplied for Bue Chandeliers, so it is the correct route for that fitting rather than buying five separate bulbs.

• Common mistake: ordering bulbs before the kit arrives, then discovering the holder is a different base.

Your five-step bulb base check

1. Identify the holder style: Look at the opening in the ceiling kit or pendant. A screw thread means Edison screw (E); offset pins mean bayonet cap (B). Checkpoint: if you cannot tell, isolate the circuit and measure the internal diameter instead.
2. Confirm the size code: Match the measurement to the code: about 27mm is E27, about 22mm is B22, about 14mm is E14 and about 15mm is B15. Common mistake: treating E14 and B15 as interchangeable. They are different fittings.
3. Choose the bulb shape for the shade: Use a globe where the bulb is on show and a smaller or coated bulb where the shade conceals the luminaire. Checkpoint: check that the bulb fits inside the shade without touching the wood or glass.
4. Check dimming before you buy: Confirm the bulb is rated dimmable and that your dimmer supports the LED load, then test one bulb across the full range. Common mistake: fitting a non-dimmable bulb to a dimmer circuit and getting flicker or buzz.
5. Buy the kit first when starting fresh: Order the ceiling kit, let it set the base, then buy bulbs that match. For chandeliers, use the specified add-on bulb set. Next step: keep a note of the base code so future bulb replacements are a one-minute job.

Products that make this decision easier

• White & Brass Ceiling Kit E27: Supplied as a standard option with most Tom Raffield wooden ceiling lights and available as a standalone product, with a matte white ceiling rose, reflective brass details and two metres of adjustable, dimmable off-white corded flex. Buying this kit sets your base as E27 before you shop for bulbs, removing the most common mismatch.
• Crompton 12677 LED G95 Globe Light Bulb: A dimmable LED globe lamp rated at 806 lumens, equivalent to 60W incandescent, with an opal glass finish that gives a bright warm light. A good fit for darker rooms needing task lighting, and the opal finish softens glare where the bulb is visible.
• Tala Gaia 6W LED Filament Light Bulb: A 6W equivalent LED with a sapphire filament array of eight thin filament LED columns inside a tinted blown-glass form, recommended to complement Tom Raffield products including the Skipper Lighting range. Choose it when you want a decorative filament look and a soft warm central glow rather than maximum brightness.
• Tala Porcelain II 6W LED Light Bulb: A 6W equivalent LED with a phosphor coating that controls the glare usually produced by filament bulbs and gives a soft ambient white light. Useful where the shade conceals the bulb but you still want comfortable, even light without a sharp point source.

Get the base right and everything else about your ceiling kit falls into place: shape, brightness and dimming all follow from a holder you have already identified. Check the holder, confirm the code, match the shade, verify dimming, and buy the kit before the bulbs.