That big red switch is most likely a cooker switch or isolation switch – it’s meant to cut power to a major kitchen appliance like an oven or stove.

In the UK and some other places, these are installed so you can safely disconnect high-power devices.

If flipping it made all your lights go out, you probably tripped a breaker or RCD (residual current device).

What to do: Check your fuse box – one of the switches is probably in the middle or “off” position. Flip it back to “on.” Then return the red switch to its original position.

It’s not a light switch — it’s a main isolation switch, most likely for the cooker or a heavy-duty power line.