Do I need a transformer for LED strip lights?

LED strip lights typically operate on low voltage DC (Direct Current) which is usually 12V or 24V.  The mains voltage within the UK is 240V making it necessary to have a driver to convert this voltage to 12V or 24V to match with your chosen LED strip lights.  

A driver is designed to perform the below functions:

1. Step-Down Voltage: It reduces the high mains voltage (e.g., 240V AC) down to the low operating voltage required by the LEDs (e.g., 12V DC).
2. AC to DC Conversion: It converts the Alternating Current (AC) from the wall socket into Direct Current (DC) that is needed for the LED strip. 

You should not wire the LED strip light directly into the mains voltage as the lights will instantly burn out. This is why a driver is a crucial component for LED strips.  

When purchasing LED strip lights you should always check the voltage and wattage required and match this to the driver.  For example - if you have a 24V strip that is 10w per metre and you would like to run 5m of the strip you will need a driver that is 24v and around 55w (it is recommended to give at least a 10% safety margin for LED strip in regards to the wattage for the driver.)  If you are looking to dim the LED strip as well you will also need to make sure the driver states that it is dimmable.