Central Networks said it follows a number of dangerous incidents in the past few months in the East Midlands.

Earlier this year boys in Long Eaton, Derbyshire, went to retrieve a ball they had kicked over a substation wall, putting themselves in danger.

The power company said children should think about where they are playing and keep away from pylons and substations.

Anita Davis, public safety adviser for Central Networks, said: "We do actually visit schools to try and put the message out to children that electricity - although it is important to us all - is very, very dangerous.

"By going into that substation to get your football back you are risking your life."