"blows main fuse board" is a little on the loose side...
Does it cause a fuse wire to melt - a Circuit Breaker for the power circuit to trip - the main, double-pole RCD to activate removing all household power ?
"when switching it on" is open to interpretation...
When power is first applied - or when a programme is selected to run ? - (At what point in the programme?)
Your dishwasher has an electrical fault and probably needs the attention of an appliance engineer.
Good luck...
Peccavi, November 2009
