Colin Birch wrote:

Hi Folks

I've got a problem with over voltage surges taking out a switch mode PSU.
I don't know a lot about electronics but looking at catalogues
VDR/Varistors look like they could be my friend. Basically I'm looking for
a simple way of blowing the inline 5a fuse if the input voltage goes over
240V AC.

Cost is also an issue here. Anyone got any suggestions on what I should
use ?

You might take a look at transzorbs:
http://www.vishay.com/diodes/protect...sd/trans-zorb/

Good Luck!
Rich