Recurring problem

I have a problem that I thought id fixed, couple of weeks ago while puddle hopping I had both main beams blow there fuses, I thought it was water shorting things out so made sure all was dry change fuses and all was well, however last night on the M5 I switched on my headlights only to find I had no main beam or flash, checked again the day light and both fuses had blown again. any ideas, being the worlds best sparky ( not ) I haven't a clue,,,,,,,,,, the motor is a 96 Def 90 300tdi with dim dip.

Cheers Coggy

The main/dip switch is often the problem area,look at the contacts in it for burning/ corrosion.

Cheers ill have a bash at it now. it could well be as the prob has to be common to both circuits