Is 6m heigh enough on a farm.  There was a recent story in the news of a tipper lorry hitting an over head power line on a farm.  The driver was electricuted when the tipper with the hydraulic arm of the tipper lorry extended came into contact with an 11kV overhead power line.

Indeed - cable routes along hedge lines and similar where nothing will drive under are preferred to going across the yard, but of course that is not always possible.
However, it is not the most dangerous thing on most farms by a long way - that is seems is currently cows.  https://www.hse.gov.uk/agriculture/resources/fatal.htm  farms are 21times more fatalities per person than the UK industry average apparently.

It used to be worse, hence the old public safety films to scare us from playing about there
https://www.youtube.com/watch?v=_we-3Uqu5sw   This is the short version.
Junior school me recalls this and this other one about railway safety (The Finishing Line) as being indelible memories.
https://www.youtube.com/watch?v=SXGqwCbeFD8

Mike.

Indeed - cable routes along hedge lines and similar where nothing will drive under are preferred to going across the yard, but of course that is not always possible.
However, it is not the most dangerous thing on most farms by a long way - that is seems is currently cows.  https://www.hse.gov.uk/agriculture/resources/fatal.htm  farms are 21times more fatalities per person than the UK industry average apparently.

It used to be worse, hence the old public safety films to scare us from playing about there
https://www.youtube.com/watch?v=_we-3Uqu5sw   This is the short version.
Junior school me recalls this and this other one about railway safety (The Finishing Line) as being indelible memories.
https://www.youtube.com/watch?v=SXGqwCbeFD8

Mike.