Water ingress

Centurian100

I own a 2003 Autotrail Chieftain.

In the offside top rear corner, behind the storage cupboards, a tubular threaded rod pokes through the inner wall. Wires come through this tube, I assume for the high level brake light? The tube is in the direction of the roof spoiler leg.

Water is dripping from this tube. 

Anyone have any similar problems or answers to this please?