Pylons and cables carry electricity through the countryside, but in cities there is no space for pylons and cables. In the city of London there are 29,000km of electrical cable buried underground. If all these cables were put end to end they would stretch to Australia. There are lots of underground substations all over London. These contain many switches and each one controls the electrical supply to specific places and famous monuments.

First broadcast:
15 October 2007

For children who are learning about electricity, this clip is useful for clarifying understanding about how electricity reaches buildings and public spaces. Children could be posed certain question to research and develop their thinking. For example, what might have happened if there is a power cut just in a certain area?