Bulb Cap Information old

The cap or base of a light bulb joins the bulb to the lamp socket in order to provide an electrical connection. Your lamp or fixture’s socket will dictate which cap or base a light bulb needs in order to fit, but there are a number of different base types and sizes to choose from, and it’s not always easy to determine which type is right for your fixture. To add to the confusion, different fixtures often feature different types of sockets.

Purchasing a bulb with the wrong cap or base is a common mistake. There are a wide variety of caps and bases available, and it can be difficult to know which one is right for your fixture, especially if its socket is not a standard size. To help you find the right cap or base for your fixture, we’ve created a guide to the most common light bulb caps and bases. If you are still unsure after reviewing our guide, we are happy to assist you to find the right bulb.

When you’re shopping for new bulbs or upgrading to energy efficient lamps, these are some of the caps and bases you’re most likely to encounter:


Bayonet Cap - BC- B22 Fit: Push and twist Commonly found on: GLS/Regular, Candle and Golfball shaped lightbulbs Key feature: 22mm in diameter	Small Bayonet Cap - B15 - SBC Fit: Push and twist Commonly found on: Candle, Golfball and other small decorative shaped lightbulbs Key feature: 15mm in diameter	Edison Screw - ES - E27 Fit: Screw in Commonly found on: GLS/Regular, Candle and Golfball shaped lightbulbs Key feature: 27mm in diameter


GU4 Fit: Push in Commonly found on: 25mm and 35mm 12volt spotlights Key feature: 2 thin pins with 4mm between the 2 pins	GU5.3 Fit: Push in Commonly found on: 50mm 12volt spotlights Key feature: 2 thin pins with 5.3mm between the 2 pins	G4 Fit: Push in Commonly found on: 12volt capsules Key feature: 2 thin pins with 4mm between the 2 pins


S15 Fit: Push in Commonly found on: 221mm and 284mm Striplights for picture lights and shaving mirrors Key feature: Bayonet style cap withouth the lugs on either end of the lamp. 15mm in diameter	G5 Fit: Push in Commonly found on: 12mm and 16mm diameter tubes. Key feature: 5mm between the 2 pins. 2 pins on either end of the tube.	G13 Fit: Push in Commonly found on: 26mm diameter tubes Key feature: 13mm between the 2 pins. 2 pins on either end of the tube.


Small Edison Screw - SES - E14 Fit: Screw in Commonly found on: Candle, Golfball and other small decorative shaped lightbulbs (Please note, 12mm CES, 10mm MES and 5mm LES screw caps are also available, please measure carefully) Key feature: 14mm in diameter	GU10 Fit: Twist and lock Commonly found on: 50mm 240volt spotlights (Please note 35mm, 63mm and 111mm lamps are also available with this fitting) Key feature: 2 thick prongs with 10mm between the 2 prongs	G9 Fit: Push in Commonly found on: 240volt capsules Key feature: 2 looped (paperclip style) pins with 9mm between the 2 loops


GY6.35 Fit: Push in Commonly found on: 12volt capsules Key feature: 2 thin pins with 6.35mm between the 2 pins

Building a Solid Knowledge Base

It’s disappointing to get home after buying a light bulb only to discover it’s the wrong size or type of base. Nobody wants the hassle of going back to the shop and making a return. Understanding what to look for with regards to terms and codes on bulb packaging can help save you time, effort, and even money in the long run.

If you are still unable to locate the cap type for your particular Light Bulb then please call us on: 01274493830.