When I sign cabinet is in a window and has warm air moving across it as the heating system runs, it warms the cabinet. Now when the heating system fan shuts down the cabinet retains more heat then the window glass. The temperature differential between the glass and the cabinet can and will cause condensation. The amount of this condensation will very by the relative humidity in the building.
No where has the OP mentioned the temperature in the room being so cold, that it leaves the cabinet so cold and nothing else in the room, so when the heat or cabinet is turned on, it makes the sign begin dripping water. I have seen that numerous times on the panes of glass of a window, but a window which is not insulated very well. The OP has already addressed that and it's not happening.
You still haven't told me or anyone else how incorrect wiring would cause moisture! Also I did not see that you said to have a constant air movement between the glass and the cabinet!
I never really narrowed it down to any one particular culprit, did I. It made mention of the fact that it could be one of several reasons for this to be happening. In fact, as someone else has mentioned, if this is a beauty parlor or some other reasonable fact simile, there could be your answer. No one has enough facts to completely diagnose this thing as being a problem from a heater vent of temperature inversion.
Waiting on you answer how something being wired wrong would cause this!
Sorry to the OP for pirating your thread!
This is not pirating if it helps solve his problem.
Gino I haveseen many thing in my life wire increectly. This has cause nuisance tripping, burnt/melted components, etc., but I have never seen moisture being caused by incorrect wiring. But I have seen moisture cause problems in electrical systems.
