I have a problem with the shower light transformer. It has been connected as per the diagram, ie N and S/L, but after operating two or three times OK the Light transformer blows. Everything else still works fine. The Fan works OK, the timer etc, but not the 12V light? I have exchanged this transformer 3 times now. I had it all fitted by a qualified spark and he seems to think that the transformers are from a bad batch, has anyone out there any ideas?