Choosing the right light bulb can feel confusing with so many modern lighting options available. But across the UK, one bulb fitting continues to stand out — the B22 light bulb. Known for its classic bayonet cap (BC) design with two secure pins, the B22 fitting remains a trusted favourite in millions of British homes, from charming Victorian terraces to sleek new builds.

In this guide, created by UK lighting experts, we’ll break down everything you need to know about B22 bulbs — and show you why they’re far more than just a standard fitting. You’ll learn about the advantages of upgrading to energy-efficient B22 LED bulbs, how to choose the right brightness and colour temperature for each room, and how to make a smart switch that saves both energy and money.

Whether you’re looking for a decorative B22 LED candle bulb to add sparkle to your chandelier or a bright, practical light for your kitchen, understanding the B22 fitting is the first step towards better, more sustainable home lighting.

1. Deconstructing the B22: The Bayonet Cap Standard

The B22 fitting, also known as the bayonet cap, is a classic lighting design from the early 20th century that still shines in modern homes. Loved for its sturdy build and easy twist-and-lock mechanism, it offers both reliability and timeless appeal—making it a favourite choice for homeowners and electricians alike.

1.1. The Mechanics of the Bayonet Cap (BC)

The name "B22" precisely defines its physical properties:

• 'B' for Bayonet: Named after the bayonet mount used on rifles, reflecting its quick-lock mechanism.
• '22' for Diameter: The base of the bulb measures exactly 22 millimetres across.

This fitting uses a straightforward, highly secure installation method:

• Alignment: The two small metal lugs on the bulb base are aligned with the corresponding slots in the lamp holder.
• Insertion: The bulb is pushed gently into the holder.
• Locking: A quick quarter-turn clockwise secures the lugs beneath the retaining springs inside the socket.

The push-and-twist design of the B22 fitting makes it more resistant to heat and vibration than traditional screw fittings. This clever mechanism ensures a secure and long-lasting electrical connection, which is why it remains a trusted choice in UK lighting today.

1.2. B22 vs. B15: Clarifying Bayonet Sizes

When dealing with bayonet caps, it is important to distinguish between the two main sizes used in British homes:

• B22 (BC): The standard large bayonet, used predominantly for ceiling pendants, main light fixtures, and larger table/floor lamps.
• B15 (SBC): The small bayonet cap, measuring just 15mm in diameter. These are often found in smaller decorative fittings, candle lights, chandeliers, or cooker hood lights.

Always check your existing bulb or fitting to ensure you purchase the correct size, as they are not interchangeable.

2. The Great Lighting Change: Why LED Is the Best Choice

The journey of the B22 bulb from incandescent to LED mirrors the UK's broader commitment to energy efficiency. While you can still technically find CFL and older Halogen B22 bulbs, the market is overwhelmingly dominated by LED technology—and for good reason.

2.1. The Halogen Ban and UK Regulation

The shift away from older technologies is not just a consumer trend; it's a regulatory mandate. The UK government has actively phased out inefficient bulbs:

• Incandescent Bulbs: Largely banned from sale years ago.
• Halogen Bulbs: The sale of most high-energy halogen light bulbs for general household use was banned in the UK from September 2021.
• Fluorescent Bulbs (CFLs): These are also being phased out from September 2023, due to their lower efficiency compared to LED, and the environmental hazard posed by the small amounts of mercury they contain.

The implication for B22 users is clear: B22 LED bulbs are the mandated, most widely available, and most effective replacements for virtually every application.

2.2. Unrivalled Energy Efficiency and Cost Savings

The core benefit of the B22 LED is its phenomenal efficiency.

Over its lifespan, a single B22 LED light bulb can save the average UK household hundreds of pounds in electricity costs, quickly recovering its initial purchase price. This makes the B22 LED replacement not an expense, but an investment.

3. Understanding Brightness and Colour: A Simple Guide to Lumens and Kelvins

The most common mistake consumers make is choosing a bulb based purely on old wattage memory. To get the perfect light, you must understand lumens and Kelvin.

3.1. Choosing Brightness: Decoding Lumens (lm)

Forget the old 40W, 60W, or 100W ratings. Brightness for LEDs is measured in lumens (lm).

3.2. Setting the Mood: Understanding Colour Temperature (K)

Colour temperature, measured in Kelvin (K), dictates the psychological effect of the light.

4. B22 Shape Variety: Matching the Bulb to the Fixture

The B22 cap is consistent, but the bulb glass itself comes in many shapes, each designed for aesthetics and light distribution. Choosing the right shape is crucial for both function and design, especially in exposed fixtures.

4.1. Standard and General Service Shapes

4.2. Decorative and Speciality Shapes

Candle Bulbs (C35)

These long, tapered bulbs are designed to resemble the gentle flicker of a flame, adding a warm and elegant touch to any space. They’re a popular choice for wall sconces, decorative light fittings, and classic chandeliers. Many of these bulbs feature a stylish B22 LED filament, offering a charming vintage glow with modern energy efficiency.

Globe Bulbs (G80/G95/G125)

Large, spherical bulbs, often used in contemporary, exposed pendant fixtures where the bulb itself becomes the statement piece of the room. They provide soft, diffused ambient light.

4.3. Filament Style: Vintage Charm Meets Modern Efficiency

The emergence of B22 LED filament bulbs has revolutionised decorative lighting. These bulbs use fine LED arrays arranged to mimic the glowing tungsten wire of old incandescent bulbs, providing that highly desirable, warm, vintage aesthetic (often in the 2200K range) while retaining all the energy-saving benefits of modern LED technology. They are perfect for bare-bulb industrial-style fittings.

5. Dimmability and Smart Lighting Integration

For many homeowners, the ability to control light intensity is non-negotiable. Modern B22 LEDs offer sophisticated control options.

5.1. Dimmable B22 Bulbs

Choosing a b22 dimmable bulb adds a layer of versatility to any room, allowing the light level to be adjusted from functional bright light to a subtle, ambient glow.

Crucial Compatibility Check:

• Bulb Label: Ensure the B22 bulb is explicitly marked as "Dimmable". A standard LED bulb used with a dimmer switch will flicker or fail quickly.
• Dimmer Switch: LED bulbs require a compatible LED-specific dimmer switch (often trailing edge) to operate correctly. Old dimmer switches designed for high-wattage incandescent bulbs will likely cause flickering or premature bulb failure. Always consult a qualified electrician if you are unsure about upgrading your switch.

6. Practical Safety and Installation Advice

The B22 cap is easy to use, but responsible usage requires attention to safety and compatibility.

6.1. Dealing with Different Fittings: B22 to E27 Adapters

Occasionally, users wish to install an E27 (screw cap) bulb into a B22 fitting using an adapter. While adapters are available on the market, caution is strongly advised.

6.2. Installation Best Practices For bayonet light bulb

Always adhere to these simple rules when installing or changing any bayonet light bulb:

• Power Off: Turn off the power at the wall switch and the main fuse box before beginning.
• No Forcing: The B22 mechanism requires a gentle push and twist. If you feel resistance, stop, remove the bulb, and ensure the lugs are correctly aligned with the slots. Forcing can damage the socket springs.
• Heat Check: While LEDs run cool, older halogen or incandescent bulbs can be extremely hot. Always wait several minutes for a burnt-out bulb to cool before handling.
• Cleaning: Use a dry, lint-free cloth to gently wipe any dust from the B22 bulb before insertion, particularly for decorative filament types.

7. The Future is Bright: Sustainability and Longevity

By choosing the B22 LED bulb, you are participating in a major national and global sustainability effort.

7.1. Environmental Impact

Switching to bayonet bulbs is a simple way to save energy and reduce your home’s carbon footprint. These bulbs use far less electricity than traditional options, helping to lower both your energy bills and your environmental impact. Their long lifespan also means fewer replacements, which cuts down on lighting waste. Plus, unlike older CFL bulbs, LEDs are mercury-free, making them safer to handle and easier to dispose of responsibly. By choosing LED lighting, you’re not just saving money—you’re also supporting the UK’s goal for a greener, more sustainable future, one home at a time.

7.2. Colour Rendering Index (CRI)

Conclusion: The Smart Choice for UK Lighting

The b22 bayonet bulb remains one of the most common and practical fittings in British homes. Today, it’s easier than ever to upgrade these traditional fittings with modern, energy-efficient light bulb b22. This simple switch allows UK homeowners to enjoy the perfect blend of classic reliability and cutting-edge technology—resulting in lower energy bills, better light quality, and a reduced environmental impact.

Whether you prefer the warm, inviting glow of an Extra Warm White B22 LED filament in your living room or the clean, bright light of a 4000K LED in your kitchen, the B22 fitting offers exceptional flexibility for every space. Switching to LED is a small change with big rewards—a real lightbulb moment for anyone looking to improve their home lighting.