Moisture in Electrical Panel-- Likelyhood?

Im trying to hunt down the cause of some moisture I found in my electrical panel. It appeared as a bit of greening of the copper #3 neutral... directly under the neutral is the busbar and it looks like some moisture dripped onto the screws of the bus and created minor water stains on them.

3 scenarios:
1. Condensation: I have a humid basement in the 70RH range. I have since plugged the service rigid conduit with duct seal in the meter base and where it enters my panel. I am also running a duhumidfier set to around 50RH.

The only evidence I see of moisture is at the above mentioned spots in the panel. If it was condensation, I would think I would see more signs of it?

2. Rain water entered the weatherhead and dripped into meter base, and then into service conduit into panel. The meter base is new, hubs are sealed. If water were to stream into the conduit, I would imagine I would see the water stain on the main breaker directly under the opening which I do not. I also did not see any signs of moisture (greening of copper) inside the meter can when I had it open to seal the conduit.

If water traveled the outside of the insulation of the neutral it would have to make and upward arch before being able to drip back down as I describe.

I have since sealed the conduit in the meter can with duct seal and also assured I have sufficient drip loop at the weatherhead mast.

The final scenario, is what I am mainly asking about.... I am not sure how likely this would be.

3. Water entered the INSIDE of the conductor and traveled along the strands INSIDE of the insulation and appeared as I describe.

Is it possible, or rather it is likely, water traveled on the inside of the wire?

If this were to occur, water would have either had to come in at the crimp connection and run upward and then down the interior of the wire and then transfer over the lugs inside the meter can and continue down the other end of the wire and into the panel. Or water would have had to come in on a not so great drip loop into the meter can along the outside of the first wire, then transfer over the lug and into the second end of the wire in the meter can.


As stated, this is what I have done to rectify this.

Assured the NEW meter can has sealed hub on top and bottom.
Corrected a suspect driploop at the weatherhead.
Started running a dehumidifier (basement stays at 70RH without it).
Plugged the rigid conduit openings with duct seal in the meter can and also where it enters the panel in hopes of keeping water out but mostly the cold and humid air that was infiltrating the panel thru this pipe.


As for the water stains in the panel. I was able to easily clean off any signs of moisture on the bus bar. However, there is a minimal amount of green remaining on the neutral wire which I cannot do anything about without reterminating it to the lug which I am not comfortable doing.

If the moisture issue has been corrected, is it OK to leave the slight green on the copper conductor? Its appearing at the tips of the strands. Once that appears, does it continue to corrode even without the presence of moisture?


THank you, if you read this far I appreciate it and any time you could lend in answering my concerns and maybe help me make sense of what is occuring....

 

I would suspect condensation.

 

Thanks Joe, that's where I am leaning too. What do you think of the 3rd scenario I propose, water traveling inside the insulation of a wire?

 

I have never seen that happen. Water can travel under the outer sheath of SEU and SER cables, but I have never seen water travel under the insulation of a single conductor.