(T) Fuse blowing/electrics

Hi, I'm a newb to the forum but having an ongoing problem with my punto that's driving me bonkers - I've got a T-reg 1.2 Selecta.

About 2 months ago, a fuse blew while I was driving, replaced the blown fuse and it seemed ok. Then 2 weeks later, another fuse blew - this was a different fuse to the original blow-out - this time it was the 15amp one on the top row (middle) of the fusebox. I replaced the fuse, it blew again immediately, tried again and the same thing happened. Left it a day while I got another fuse, replaced it and it was fine. This happened again about a week later so this time I put it into the garage for a check-up - they run full diagnostics but couldn't see a wiring fault, they replaced the fuse and the car was fine again....for about 2 weeks!

I drove the car fine all this week, no problems whatsover, then yesterday morning, jumped in it to go to work at 8am and the fuse blew - and it was raining. I changed the fuse 3 times, but it blew again every time.

When the fuse blows, it nearly always seems damp or raining. I start the car ok, automatic locking kicks in fine - then I put my foot on the brake pedal to take the car out of Parking (its an automatic) and the fuse blows. At this point I can't move the gear selector and if I'm really unlucky, I can't remove the key either (thank goodness for the emergency release process!). Whenever the fuse goes, it appears to be the brake pedal that triggers it.

I am getting increasingly frustrated with the car and my patience is running out - anyone else out there had this sort of problem? Any ideas on what it can be and how to fix it?

Help!

whats the fuse for?should say inside the fusebox cover

Unless your familiar with voltage drop & continuity tests all you can do is visually check the wiring especially where it goes close to brackets or moving parts especially in engine bay...try removing brake light bulbs aswell.
You really need to determine what circui(s) use the fuse that keeps blowing otherwise just save time & frustration & book in to auto electrician who should trace the short quickly.

could it be a poor earth on the brake-light circuit? check the earthing points for corrosion. you'll find the points in the Haynes Manual (the bible)

Thanks for your suggestions - I'm off to have a look in my Haynes manual and check the wiring around the brake lights when it stops raining.