Lighting is one of the most important aspects of any home, but choosing the right bulbs and fixtures starts with understanding something very simple yet crucial: the light socket. Light sockets determine which bulbs you can use, how they connect to electrical power, and even how safe and efficient your lighting will be.
Whether you're replacing a bulb, upgrading fixtures, or choosing new lighting for a renovation, knowing the different socket types can save you time, money, and frustration. This guide explains the most common socket types and what every homeowner should know about them.
1. E27 (Edison Screw) — The Most Common Household Socket
The E27 socket is widely used around the world and is known for its threaded, screw-in design.
Best For:
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Ceiling lights
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Lamps
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Batten fix fittings
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Most general household fixtures
Features:
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27mm screw base
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Compatible with LED, CFL, and incandescent bulbs
If you’re unsure which socket your fixture uses, E27 is the most likely candidate.
2. B22 (Bayonet Cap) — Secure and Twist-Lock Design
The B22 socket is another common type, especially in older homes or certain regions.
Best For:
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Ceiling roses
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Traditional fixtures
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Fixtures requiring an anti-vibration lock
Features:
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Push-and-twist mechanism
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22mm base
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Strong, stable connection
B22 bulbs are easy to install and ideal where bulbs may loosen due to movement or vibration.
3. GU10 — The Standard Socket for Downlights
Most modern LED downlights use GU10 sockets, known for their two short, cylindrical pins.
Best For:
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Recessed downlights
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Track lights
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Spotlights
Features:
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Twist-and-lock connection
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240V operation
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Designed for directional lighting
GU10 bulbs create focused, bright lighting perfect for kitchens, hallways, and living rooms.
4. E14 — Small Edison Screw for Compact Fixtures
The E14 socket is the miniature version of the E27.
Best For:
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Chandeliers
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Wall sconces
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Decorative fixtures
Features:
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14mm screw base
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Ideal for small bulbs like candle or golf-ball styles
It's perfect when space is limited or the fixture requires a delicate design.
5. G9 — Compact Socket for Modern Decorative Lighting
The G9 socket uses two small looped pins and is frequently used in stylish, contemporary fixtures.
Best For:
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Pendant lights
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Designer lamps
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Decorative wall fixtures
Features:
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Push-fit mechanism
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Compact size
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Common in high-end architectural lighting
G9 LED bulbs are now widely available, replacing older halogen versions.
6. MR16 (GU5.3) — Low-Voltage Downlight Socket
The MR16 socket looks similar to GU10 but operates on 12V, often using a transformer.
Best For:
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Low-voltage downlights
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Display lighting
Features:
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Two thin pins
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Requires a compatible transformer
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Used in older or specialty lighting systems
When upgrading from halogen to LED MR16 bulbs, ensure the transformer is LED-compatible.
How to Identify Your Light Socket
You can quickly identify socket types by checking:
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The base of the existing bulb
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The fixture label or stamp
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The fitting size and shape
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Whether it screws in, twists, or pushes
When in doubt, take the bulb to a lighting store or compare it to a size chart.
Conclusion
Understanding light socket types is essential for choosing the right bulbs, upgrading fixtures, and maintaining safe lighting throughout your home. From the everyday E27 to specialized sockets like GU10 and G9, each type serves a unique purpose.
Whether you’re renovating, replacing bulbs, or shopping for new lighting, having this knowledge ensures better compatibility, safety, and overall lighting quality.
