What is a good height for a run fence?

[Aussie Rooster]

Just finishing building my first chook house and will start to build the chicken run in a couple of weeks. Does any one know what would be a good height for the run fence to be? Only really have to worry about foxes in the area and the chooks will be locked in at night.

 

[Imp]

If it is covered. It is a lot easier to live with if you can walk in it, upright.

Imp