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All of the different fitting types
It’s a moment every homeowner has experienced. A light bulb goes out. You take it out, head to the store, and grab what looks like the right replacement. But when you get home, you discover it won’t screw in or twist into place. It’s the wrong one.
Let's be honest, the world of light bulb fittings can feel like a confusing alphabet soup of codes like E27, GU10, E14. But it's actually much simpler than it looks!
Screw vs. Twist
Before we get into the nitty-gritty codes, just know that almost all the light bulbs in your home will fall into one of two main categories. Understanding this makes everything easier.
- Screw-in Fittings: This is the classic light bulb base with a threaded metal screw. It’s named the "Edison Screw" after its inventor, Thomas Edison.
- Twist-and-Lock Fittings: Instead of a screw, these have two little 'feet' or pins on the base. You push the bulb in and give it a slight turn to lock it into place.
The most common fittings
While there are dozens of specialty fittings out there, you only need to know a handful to cover about 99% of the lights in a typical home.
E27: The Big Screw Fitting
This is the king of fittings, the one everyone pictures when they think of a light bulb. The 'E' stands for Edison and the '27' stands for 27 millimetres, the diameter of the base. It’s the most common fitting by far.
Where you'll find it: Ceiling pendants, table lamps, floor lamps, and outdoor wall lights.
E14: The Small Screw Fitting
This is the E27's little brother. It has the same screw design but is much slimmer, with a diameter of just 14 millimetres. It's often called the "Small Edison Screw" or SES.
Where you'll find it: Chandeliers, decorative wall lights, smaller table lamps, and appliance bulbs (like for an oven or fridge).
GU10: The Spotlight Superstar
This is the most common fitting for modern spotlights. The base has two short, thick, T-shaped 'feet'. You simply push it into the socket and give it a quarter-turn to lock it in. These run on mains voltage (230V), so you don't need a separate transformer.
Where you'll find it: Recessed ceiling downlights (especially in kitchens and bathrooms), track lighting, and adjustable spotlights.
MR16 (or GU5.3): The Thin Pin Spotlight
Heads up! This is the one that often causes confusion. An MR16 looks almost identical to a GU10 from the front, but the base is very different. Instead of thick, twistable feet, it has two thin, needle-like pins that push straight into the socket. These are low-voltage (12V) bulbs and require a transformer to work.
Expert Tip: Always check if your spotlight fitting has thick twist-in sockets (GU10) or thin push-in holes (MR16) before you buy a replacement!
Always choose the right one
Want to guarantee you never buy the wrong bulb again? It's simple. Before you go shopping or browse online, do one of these two things:
- Take a photo of the base of your old bulb. Make sure any text on the bulb is readable.
- Bring the old bulb with you. It's the most reliable method of all!
No more guesswork!
And that's really all there is to it. While the codes might seem technical, once you can recognise the big players: the E27 big screw, the E14 small screw, and the GU10 twist-lock, you'll be able to handle almost any lighting task in your home.
Armed with this knowledge, you can say goodbye to those frustrating return trips to the store and shop for your lighting with total confidence. Still unsure which fitting you have? Snap a photo and send it to our experts at Fixerio. We're always happy to help you find the perfect fit!
