What is the cause

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shboal11

shboal11

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Grand Terrace, California
i have a 200 amp sub panel 100 ft away from the main, and 15 feet below in pvc conduit. The sub is fed by 3/0 4 wire thwn and a #4 ground to a ufer at the sub. There is what appears to be calcium deposit on the outside of the feeder wires. the buss bar is burnt. The ground to the ufer is burnt in the sub panel and the wires on most of the breakers, grounds and neutrals show signs of corrosion. The cooper feeder wires are burnt and corroded ( black suit) at the sub only. the sub is also feed by 2 inverter's for solar. i have to replace both 9 year old inverters in the past 3 months. The load on this panel is primarly the 50 amps that goes to the well pump. This sum is fed about 25 amps of solar at 240. I have pictures too
 
My first inclination would be corrosion. What is the environment? Coastal causing salt water corrosion? Or perhaps swimming pool chemicals like chlorine?

-Hal
 
The 200 amp sub panel is a nema 1 inside a steel building. the main panel at the house is about 75 - 100 feet away and about 15 in elevation higher. The location is Redlands California. All the wires at the main panel show no
signs of corrosion
Slide1.jpg.
 
Seal the conduit to the well also. There is a possibility that you have hydrogen sulfide or other corrosive gasses outgassing from the water in the well. It could be traveling thru the conduit from the well head to the electrical panel. Is there corrosion in the pump panel or control box?
 
Dzboyce said:
Seal the conduit to the well also. There is a possibility that you have hydrogen sulfide or other corrosive gasses outgassing from the water in the well. It could be traveling thru the conduit from the well head to the electrical panel. Is there corrosion in the pump panel or control box?
Click to expand...

I would agree that there is a corrosive atmosphere involved, but it seems odd that it is attacking the feeder when the conduit going out the back of the panel and the bottom of the panel have branch circuit conductors that don't seem to be affected.
 
Off topic, but why do some of those pictures look like mirror images compared with others. Like the blue branch circuit conductors look like they are turning left in one picture and right in another? The up/down orientation is the same (you can tell by that lug and conductor that feeds it).
 
oldsparky52 said:
I don't know about others, but I have no idea what you are trying to convey.
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Here is a drawing and a pic
6e887364cb3d61e5387fe6b5e160b2b5.jpg
1df27d16ce985a87de8519e385a6af0c.jpg


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shboal11 said:
The 200 amp sub panel is a nema 1 inside a steel building. the main panel at the house is about 75 - 100 feet away and about 15 in elevation higher. The location is Redlands California. All the wires at the main panel show no
signs of corrosion
View attachment 18099.
Click to expand...
Whatever else is going on, the picture on the top left of the photocollage shows that the conduit coming in from the bottom was flooded. The discoloration on the conductors stops where the water level reached the top of the bushing and spilled over into the enclosure.
 
Dzboyce said:
Seal the conduit to the well also. There is a possibility that you have hydrogen sulfide or other corrosive gasses outgassing from the water in the well. It could be traveling thru the conduit from the well head to the electrical panel. Is there corrosion in the pump panel or control box?
Click to expand...
The only corrosion is in this panel. The out Building with the well has no corrosion and the main has no corrosion

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The conduit flooded, stagnated, went anaerobic (septic) and evolved out H2S. Combined with moisture, this attacked the copper wire and buss bars leaving the blackish copper sulfide (not sulfate which is green - could have been reduced via atmosphere or electricity ).

The white stuff on the wire insulation looks almost exactly like what grows on/attacks concrete in a waste water plant/wetwell vault where large amounts of H2S are generated.

That's my guess anyway. Sealing the conduit should keep the gasses/corrosion out tho the water/flooded condition will always be there. It doesnt take much H2S to cause bad corrosion as it forms sulfurous/sulfuric acid on contact with moisture. (eta: I dont think H2S eats AL the same as Cu, hence why the Al seems unaffected; it's likely the surface layer of aluminum oxide or No-Ox protected it from the fumes)

The well has enough fresh water entering that it will not generate H2S - if it did, it would be noticeable taste in the drinking water.

eta: the white stuff could be calcium deposits as you thought - definitely a mineral deposit of sorts. That is harmless tho.

In addition to sealing the conduit, I'd No-Alox everything and provide some sort of ventilation if possible - perhaps a small fan aimed at the panel. Should keep gasses that do make it thru from concentrating and corroding everything. Moisture control would help as well

The main panel likely doesnt see enough humidity to get the corrosion, hence why it's okay.
 
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