I rewired my loft three or four years ago fitting two twin 58w fluorescents. Been up and down getting Christmas stuff down, about the third time there was a pop from one of the fittings and it stopped working. Back up there today and a bigger pop from the other which took the breaker out now I have darkness, looked in both and no signs of damage or water ingress and whilst it may be a bit damp up there I never expected them both to go at virtually the same time.