Distribution Network Operators (DNOs) are responsible for your connection to the grid.
You might need your DNO if:
there’s a power cut
you’re doing works on site that affect your electrical connection
you need technical details about your supply
You can find out who your DNO is by following the steps here: Who’s my electricity network operator? - You’ll just need to pop in your postcode and it will tell you the name of your DNO and how to contact them.