A Complete Guide to Lamp Holders

These lighting components are a familiar feature of every home, factory and office. They hold light bulbs in place and provide an electrical connection to power them. Some light sockets include a switch to power on the bulb while others do not.

Lamp holders come in a variety of shapes and sizes and sometimes support other accessories or parts of the fixture such as light shades. They have several alternative names, including light sockets, lamp fittings, light holders, and bulb holders.

Lamp holders are designed to fit specific light bulb sizes and cap types and they will not fit any others, so always check this carefully. Amongst the most widely used bulb types are:

GLS

What is a GLS bulb? General Lighting Service bulbs feature the familiar, basic, pear-shaped design that has been in use for more than a century. They may have either bayonet or screw caps.

CFL

Compact fluorescent lamp bulbs are the energy-saving successor to traditional bulbs. Instead of a burning filament, they contain mercury vapour which emits ultraviolet light in response to electrical current. This UV light, in turn, triggers a coating of phosphorus within the bulb to glow, emitting light. Typically, CFL bulbs feature various stick and spiral shapes but traditional pear designs are also available.

LED

Light-emitting diode bulbs are the next step beyond CFL lighting. Extremely energy-efficient and with long lifespans, they provide instant-on lighting. They are built around a semiconductor, a device with electrical conductivity halfway between metal and insulation. This emits light in response to electrical current.

Lamp holders are available in a variety of designs for different uses. Let’s take a look at the main types of holder for lamps:

Lamp Holders for Table Lamps

Lamp holders for table lamps are relatively simple, upright devices which may feature all major mount types. Some table lamp holders come with switches for easy control.

Batten Lamp Holders

Batten lamp holders are small, screw-on devices that can be attached to a door or wall fitting vertically. They are available with Edison screw and bayonet cap mounts, in white, black and other colours.

Lamp Holders for Bottles

Lamp holders for bottles create eye-catching lighting. A cable and switch are threaded through a hole drilled into the base of an empty bottle. This then extends up to a bulb holder inserted into the neck. As these are primarily decorative lamps, a variety of cable colours and switch colours are available.

Pendant Light Fittings

Pendant light fittings and parts are made for suspended ceiling lamps. They hang from a cord or cable and the bulb is inserted by pushing or screwing directly from below.

Switched Lamp Holders

Switched lamp holders feature built-in power switches as an alternative or addition to the main lamp switch.

The technique required for fixing bulbs into lamp holders varies according to bulb type and lamp holder mount - i.e. the type of connection.

Light bulbs are available in multiple sizes and designs. A key differentiator is in the base - the part that clips or screws into the bulb holder.

Here are the key types of lamp bulb base:

• The familiar bayonet cap features opposing prongs that slot into the holder. B is used to indicate a bayonet cap in bulb names. - e.g. B22
• The threaded Edison Screw, or ES, is now more widely used than the bayonet cap. E in bulb names indicate this base - e.g. E27
• GU bases - GU4, GU10 and others - are used in several modern Halogen and LED bulb designs. They feature two protruding prongs with a circular head that twists and locks into place. G indicates a dual or multi-pin base, while the U stands for universal. A variant is the G base, which features two thinner prongs for quick insertion into compatible slots. You will find these on a variety of bulbs including fluorescent tubes (G5 bulbs), LED strips, and halogen capsules normally used in kitchen appliances (G4 bulbs)
• The R-type base features recessed contact points and ceramic tips. A prominent example is an R7 bulb, a linear halogen capsule used in floodlights and uplights, which is also available as an LED lamp

Lamp fittings are made from a variety of heat-resistant materials because they need to withstand the high temperatures generated by most bulbs. The principal materials used to make lamp holders are as follows:

• Metal - for example, brass and copper lamp holders
• Plastic lamp holder fittings and sockets - the polymers (synthetic materials) polycarbonate (PC), polybutylene terephthalate (PBT) and phenol-formaldehyde (phenolic)
• Ceramic - for example, porcelain lamp holders

If you have purchased a lamp holder kit for assembly, it is important to proceed cautiously when you reach the wiring stage. Wiring an electrical device poses obvious risks so speak to a professional if you are in any doubt.

Learn how to wire a plastic or metal lamp holder below:

1. Attach your lamp fitting to the holder - pull the thread through and tighten the screw at the bottom of the holder to lock it into place
2. You will normally then have two wires to attach to the holder - a live wire, typically brown, and a neutral wire, typically blue. Insert these into either socket in the connection unit and tighten the screws
3. Attach the connection unit to the upper part of the lampholder. This should snap firmly into place but if you encounter resistance move it in the opposite direction to apply, or check that the screw attaching the unit to the holder is tight
4. Assemble the full bulb holder, again ensuring that the parts are screwed or snapped in the correct direction

Is B22 the Same as E27?

These two bulb types are quite similar. Both provide warm, steady light in commercial and domestic settings and they are used for many of the same purposes. However, they feature different bases. The B22 has a push-and-twist bayonet cap while the E27 has a revolve-to-insert Edison screw.

What is the Difference Between E14 and E27?

These are both Edison screw bulbs, with that distinctive threaded base. The difference lies in the diameter of the socket, which is indicated by the number. The smaller E14 has a socket diameter of 14mm, while its larger counterpart has a diameter of 27mm.

What is an E14 Light Bulb?

The E14 is one of the most widespread twist-in, Edison screw bulbs in contemporary use. It is a smaller variation of the E27, with a socket diameter of 14mm.

Is E7 the Same as ES?

Not quite. ES is short for Edison screw - these are the threaded bulb bases that are screwed into lamp holders to secure the bulb. They are named after their inventor, legendary 19th-Century engineer Thomas Edison. E7 bulbs are one smaller size of ES bulb, with a socket diameter of 7mm. These typically have a candle-like shape.