I've got a circular saw that has been responsible for damaging a total of three extension leads. Not in the typical sharp bit cutting the cable you may have expected.
I've had the saw for a year and use it infrequently. The first extension lead was a few months ago and I assumed was just time for the extension lead to give in. Then this week it killed another, so I tried a third lead which did the same thing (and confirmed a likely correlation). Each time there is no catastrophic failure, the saw simply stops receiving power.
It seems the saw is overloading the extension lead and frying it in some way. The saw still works when connected directly to the mains. However the leads although 'surge protected' seem to be incapacitated. Two of them have a trip button which doesn't seem to have revived them. There are no obvious physical signs that the extension leads are broken, they just no longer supply power to any devices in any of the sockets.
The saw itself was bought here
and the third was similar to this
What could be causing this?