Light Bulb Adaptors

Which light bulb adapter do I need?

Take out the bulb your lamp or light fitting uses now and read the code on its cap or packaging, because that is the cap your holder takes and the end the adaptor must match. Then check the code on the bulb you would like to use, which is the cap the adaptor must accept.

Conversion adaptors are usually named fitting first and bulb second, so an E27 to GU10 adaptor screws into an E27 holder and takes a GU10 spotlight bulb. Check the description to confirm which end goes into the holder, because the reverse conversion is a different part.

Light bulb adaptor cap codes explained

In a cap code, the letters name the type and the number gives the size in millimetres. B22 is the bayonet cap usually found on UK ceiling lights, with side pins that push in and twist to lock. E27 is the larger screw cap, often marked ES, while E14 is the smaller screw cap, or SES, common in table lamps, chandeliers and wall lights.

GU10 is the mains spotlight cap, with short, thick pins that push in and twist to lock. G9 is a small capsule fitting with looped pins that push straight in. Match the codes on the adaptor to your fitting and your bulb, and the right part is easy to spot.

What wattage can a light bulb adaptor take?

Check the adaptor's maximum load before you choose a bulb, and treat it as the ceiling for whatever you fit. The lamp or light fitting has a maximum of its own as well, so follow whichever limit is lower.

LED bulbs make this simple. They draw far fewer watts than incandescent or halogen bulbs for a similar amount of light and run much cooler, which leaves comfortable headroom within the limit. If you are replacing an old filament bulb, compare by brightness in lumens rather than by watts.

Will a light bulb adaptor fit in my lamp or shade?

A conversion adaptor adds its own length between the holder and the bulb, so the bulb sits further out. That can leave it hanging below a shade's rim, and in an enclosed fitting or a snug glass shade there may be no room for it. Measure the space between the holder and the shade or diffuser, and compare it with the adaptor and bulb together.

Some of the adaptors we stock are small, which helps where space is tight. Weight matters too: a heavy bulb on an adaptor puts extra strain on the holder, particularly in a wall light where the holder sits sideways, so a lightweight bulb is the better match.

Light bulb adaptor materials and finishes

We stock metal adaptors and a polycarbonate adaptor. Metal is hard-wearing, while polycarbonate is a tough, lightweight plastic that keeps weight off the holder. Whichever body you choose, the caps at either end are what need to match your codes, and the load rating is what limits the bulb.

Finish only matters where the adaptor will be seen, such as on a bare-bulb pendant or a lamp without a shade. We stock an adaptor in white or black, so it can match the holder, flex or ceiling rose.

How to fit a light bulb adaptor

Switch off at the wall or unplug the lamp, and let the old bulb cool before removing it. Push and twist a bayonet adaptor, or turn a screw-cap adaptor, until it sits firmly without forcing, then fit the bulb into the adaptor. Use a single adaptor for the whole conversion rather than stacking adaptors together, and if an adaptor ever feels loose or runs hot, switch off and take it out.

Fitting an adaptor into an existing holder is no harder than changing a bulb. Replacing the holder itself, or anything else that means working on fixed wiring, is a job for a qualified electrician, and in England and Wales that work must meet Part P of the Building Regulations.