Lighting & Bulbs · 6 min read · Beginner

How to Choose a Replacement Light Bulb Safely

A simple replacement checklist covering cap type, size, brightness, colour, dimming and fitting condition before you buy.

Key points & steps

Turn the fitting off, allow the existing lamp to cool and remove it safely. If it is a portable lamp, unplug it first.
Identify the cap/base code and inspect the old lamp for voltage, wattage and other markings.
Check the light fitting label or instructions for the permitted lamp type and maximum rating.
Choose the brightness in lumens, then decide on colour temperature and beam shape/angle where relevant.
If the circuit uses a dimmer, select a lamp that is marked dimmable and check the dimmer manufacturer’s LED compatibility guidance.
Check the new lamp’s physical length and diameter against the shade, downlight or enclosed fitting before ordering.
After fitting, stop using it if you notice flickering, buzzing, repeated tripping, unusual heat, discolouration or a loose/poor connection.

For downlights, use replacement lamps or components that the fitting manufacturer confirms are compatible.
Never change a lamp while energised and hot.
If the holder or fitting is damaged or overheated, seek competent electrical advice rather than treating it as a bulb-selection problem.