Lamp Holder Types: E27, E14, GU10, G9 and B22

The lamp holder (also called the bulb base or socket) is the part of the bulb that fits into the light fixture and carries the current to it. The most common types in Romanian homes are E27 (the "large" holder, with a 27 mm thread) and E14 (the "small" holder, with a 14 mm thread), followed by the pin bases used for spotlights: GU10, GU5.3, G9 and GX53. The number in the name tells you the size: for E27 and E14 it is the thread diameter in millimetres, while for GU10, GU5.3 or G9 it is the distance between the pins. Below you will find each type explained, a comparison table and answers to the most frequently asked questions.

Why are there so many lamp holder types?

Today's bulbs come in a wide range of shapes and sizes to suit every kind of light fixture: large chandeliers, discreet wall lights, spotlights recessed into a false ceiling or decorative lamps. Choosing a bulb is not just about shape and design; above all, it is about the type of lamp holder that is compatible with the fixture. A bulb with the wrong base will either not fit or will not make proper contact, which is why it is worth knowing what each code means.

What is a lamp holder?

The lamp holder is the component that connects the bulb to the light fixture. It holds the bulb in place mechanically and delivers the electrical current to it. Each type of holder only works with certain bulbs, so it is essential to choose the right bulb for the fixture, so that it works properly and sits securely.

Lamp holder (bulb base) types: comparison table

Holder	How it fits	Size	Voltage	Where you will find it
E27	Thread, screws in	27 mm diameter	230 V	Chandeliers, ceiling lights, floor lamps, table lamps, many outdoor wall lights
E14	Thread, screws in	14 mm diameter	230 V	Candelabras, wall lights, small table lamps, "candle" bulbs
GU10	2 pins with thickened ends, push in and twist	10 mm between pins	230 V	Recessed spotlights, track spotlights, accent lighting
GU5.3	2 thin pins, push in	5.3 mm between pins	Low voltage (usually 12 V), via a transformer	False-ceiling spotlights, fixtures recessed into furniture
G9	2 wire loops, push in	9 mm between pins	230 V	Modern chandeliers, decorative wall lights
GX53	Flat disc, twist to lock	–	–	Slim spotlights and ceiling lights
B22	Bayonet: push and twist	22 mm diameter	230–240 V	Rare in Romania; standard in the United Kingdom

Popular lamp holder types at a glance

1. E27 holder – the large, standard holder

• Description: the most common lamp holder, used in most light fixtures around the home. The "E" stands for Edison, and 27 is the thread diameter in millimetres.
• Compatibility: large-thread bulbs (Edison Screw), in classic, globe or decorative filament shapes.
• Applications: chandeliers, ceiling lights, floor lamps, table lamps.

If you only want to replace the holder on a lamp, or create a minimalist pendant with an exposed bulb, E27 holders are also sold separately, in black, white, chrome or brass finishes.

2. E14 holder – the small holder

• Description: similar to the E27, but with a smaller 14 mm thread. When someone talks about a "small-base bulb", they usually mean E14.
• Compatibility: "candle" bulbs or small globe bulbs.
• Applications: candelabras, decorative lamps, wall lights, chandeliers with several arms.

Small-base E14 LED bulbs use little energy and heat fabric lampshades far less than the old incandescent bulbs, which makes them the natural choice for indoor chandeliers with many light sources.

3. GU10 holder – for spotlights

• Description: used mainly for spotlight bulbs. The two pins have thickened ends; the bulb is pushed in and twisted until it locks.
• Compatibility: LED bulbs (most of them nowadays) or halogen bulbs, with two pins and a twist-lock fitting.
• Applications: recessed spotlights, track spotlights, accent lighting. See also our range of indoor spotlights.

4. GU5.3 holder – low-voltage spotlights

• Description: similar to the GU10, but it runs on low voltage (usually 12 V), so it needs a transformer or a power supply.
• Compatibility: bulbs with two thin pins that are simply pushed in.
• Applications: false-ceiling spotlights, fixtures recessed into furniture.

Please note: a GU10 bulb will not fit a GU5.3 holder, nor the other way round, and the voltages are different. Never force a bulb into a holder it was not made for.

5. G9 holder – capsule bulbs

• Description: used for compact bulbs with no thread, with two loop-shaped pins 9 mm apart.
• Compatibility: "capsule" bulbs. Halogen G9 bulbs can no longer be placed on the EU market since 1 September 2023, so today you buy G9 bulbs in their LED version.
• Applications: decorative lighting, modern chandeliers, small wall lights.

6. GX53 holder – flat spotlights

• Description: a flat, disc-shaped bulb that twists into place.
• Applications: shallow recessed spotlights and slim ceiling lights, useful wherever there is little room in the ceiling or in the furniture.

7. B22 holder – bayonet

• Description: known as the "bayonet cap"; 22 is the diameter in millimetres.
• Compatibility: bulbs with a push, twist and lock fitting.
• Applications: it is the standard in the United Kingdom and a few other countries; in Romania you rarely come across it, usually on light fixtures brought from those countries.

Outdoor bulb holders: what you need to know

Outdoor lighting uses the same lamp holder types as indoor lighting, most often E27, but also GU10 for garden spotlights. What makes the difference is not the holder but the light fixture: it must have a degree of protection against water and dust (IP rating) that suits where it is installed. You will find the details in our guide to IP ratings for garden lighting, and suitable models in our outdoor wall lights category.

How do you choose the right lamp holder?

• Type of light fixture: check the technical data sheet or the label inside the fixture to see which holder it has and the maximum wattage it accepts.
• Type of bulb: LED bulbs are made for almost every type of holder, so you can usually find an LED replacement for your old bulb.
• Size and voltage: make sure the holder and the bulb match in both size and voltage (230 V or 12 V).
• Available space: with small lampshades or chandeliers with slender arms, the length of the bulb matters too, not just the holder.

Frequently asked questions

What does "small holder" mean?

In everyday speech, a "small holder" usually means E14, with a 14 mm thread, as opposed to the "large" E27 holder. People sometimes call pin bases such as G9 or GU10 "small" as well, so it is a good idea to check the code printed on your old bulb.

Which small-base LED bulb should I choose?

Look at the light fixture first: if it has a 14 mm thread, you need an E14 LED bulb. Then choose the shape (candle or small globe) and the colour temperature (2700–3000 K for warm light, 4000 K for neutral light), and check whether you need a dimmable version (with adjustable brightness).

What is a G9 holder?

G9 is a base with two loop-shaped pins 9 mm apart, for small capsule bulbs running at 230 V. It is used in modern chandeliers and decorative wall lights. Halogen G9 bulbs have not been placed on the EU market since September 2023, so G9 LED bulbs are used instead.

What types of bulb base are there?

The most common are E27 and E14 (threaded), GU10, GU5.3 and G9 (pin bases), GX53 (flat disc) and B22 (bayonet). The table above shows at a glance how each one fits and where it is used.

Can I put an E27 bulb into an E14 holder?

No. The threads have different diameters (27 mm and 14 mm), so the bulb will not fit. Always buy a bulb with the same base code as the holder on your light fixture.

Which holder is used for outdoor bulbs?

Most often E27, on wall lights and garden lamp posts, and GU10 on some spotlights. What matters is that the whole light fixture has an IP rating suitable for outdoor use.

The lamp holder is a small but essential detail when you choose a bulb. Whether you need an E27 holder for an ordinary ceiling light or a GU10 for a modern spotlight, knowing the types of lamp holder helps you buy the right bulb first time. If you are not sure which bulb suits a light fixture from our store, drop us a line and we will help you choose.