glurbs,

good answer mate, and your english is perfectly understandable. it takes a lot of courage and effort to use a forum in another langage, and appreciate people like you doing it. it makes the community a better place if we have more nationalities and cultures contributing to it.

i think that you're right too. the std wiring does seem to be on the limit with new fans in good condition. when they get old, the bearings get noisy and require more power (current) to drive the fans, and this is what causes the fuse box to melt.

a cure is to rewire the circuit as already shown, and maybe fit more efficient fans that provide the same airflow capabilities using less power input.