Main Breaker and Conductors corrosion

[larmee]

Investigated a situation at a local bank involving water seeping out of the conductors inside the switchgear onto the main breaker. The installation has 4 sets of 350 parallel comprising a 1200 ampere service. The installation was initially installed in 2006. There are 4 sets of PVC conduits running from the service pole into the switchgear located approx. 150 feet away. The conduits at the service point have drip loops and are taped and there are loops formed in the conductors inside the gear. No water is visible in the conduits in the raceways or in the switchgear itself. All 4 sets of conductors have water present and corrosion has developed on all the lugs. The neutral lugs are stacked 3 high and one offset and all 4 are corroding as well. I have observed actual water seeping out of the conductors. Besides the obvious that water is inside the jacket any ideas on how it is making its journey around all the bends and loops? The conductor size is 350 type is THHN / THWN. The service is not overloaded with the peak load being 538 amperes since installation.

 

[big john]

...Besides the obvious that water is inside the jacket any ideas on how it is making its journey around all the bends and loops...?

Capillary action between the closely spaced strands can wick water for a long distance.

But that still don't answer the question of how it's getting in all the conductors to begin with. I'd start with the obvious and do a close inspection of the weather-head.

 

[Jon456]

As Big John stated, capillary action will wick water between the strands, even allowing water to flow uphill some distance. But I suspect there is gravity also at work here (i.e., there is water getting inside the wire jacket at a point higher than the switchgear). If that is true, then the insulated wire is acting just like a pipe (that's severely restricted by the wire strands inside).

Can you take photos of the service point and the exterior conduit?

 

[larmee]

Thanks

Thanks

As Big John stated, capillary action will wick water between the strands, even allowing water to flow uphill some distance. But I suspect there is gravity also at work here (i.e., there is water getting inside the wire jacket at a point higher than the switchgear). If that is true, then the insulated wire is acting just like a pipe (that's severely restricted by the wire strands inside).

Can you take photos of the service point and the exterior conduit?

After some experiments at the shop today I am convinced that you and Big John are spot on. Looking at some site photos the conductor length on the utility side of the drip loop is considerably longer providing a slingshot for water around the drip loop. It is apparent that the joints made by the utility are not keeping the water from entering the conductor jacket. Since the installation has been in place for almost 10 years I believe that the water has continued to enter the conductors until it had no where to go. I sincerely appreciate both of your responses.