What could be causing condensation on attic pipes?
What kind of pipes are in the attic space?  There should not be any water pipes otherwise you have a risk of burst pipes.   It sounds like there is a problem with the vapour barrier having gaping holes and missing or insufficient insulation.

A common problem with attic fans is that the ductwork is cold and when the fan is switched on for showering, then the humidity condenses in the ductwork and can run back inside the fan housing.

This doesn't sound like excess moisture -- to me that would mean a lot of moisture on the windows, for example.