Dam Corrosion!

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big john

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Portland, ME
So I've gotten an interesting new job as an electrician for some hydroelectric dams and I need to come up with a battle-plan to combat the effects of water on the electrical equipment. There is a tremendous amount of water seepage through the dam (surprise, surprise) which, combined with the chemicals in the concrete quickly destroys any metal. A lot of equipment cannot be replaced just yet and has to be "fortified" instead.

  • I'm thinking of making it a policy to use PVC and fiberglass anywhere it's in contact with the dam face.
  • Use some sort of antioxidant on electrical connections to help prevent corrosion and galling. Would NoAlox work on lightbulb threads and copper connections? Not sure about high-heat and copper applications.
  • Liberal use of silicone, duct-seal, and weather-proof fittings to help prevent the incursion of water.
  • I've thought about wrapping all devices and connections in tape, but I'm not sure if any amount of tape would make a difference in a high-humidity environment. Maybe just a waste of time?
  • Some type of corrosion-inhibiting coating. CRC advertises a bunch of sprays that are supposed to inhibit corrosion on electrical equipment. I'm weary of anything that simply gets sprayed all over the place. Is the stuff a conductor or an insulator? Don't I run the risk of making things into insulators/conductors when I don't intend to by coating them?
Anyone have any other ideas or tricks? Please note, I do have a very limited budget, so while making everything stainless and "marine grade" would be ideal, it ain't gonna happen.

Thanks a bunch.

-John
 
I probably wouldn't use No-Lox in a light socket as it does conduct. Poof! You might investigate if there are any marine grade alternatives for fixtures, lamps and what not. Silcone is used a lot in marine applications to seal things.
 
wawireguy said:
I probably wouldn't use No-Lox in a light socket as it does conduct. Poof!
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But... don't I want something conductive? Seems like a bad idea to smear something non-conductive on a conductive terminal. High resistance = heat, right? If it doesn't matter, we have white-lithium that would probably work.

-John
 
I don't know if it's the same for big john, but we've done work in the dam here and they made it very clear taking pics inside the dam was strictly forbidden.
 
So, here are some pictures of what I'm up against. These are worst-case examples, but it gives you an idea of what the environment can do. This is a 3R motor starter. The damage is simply the result of the normal humidity and condensation within the turbine pit. This was a junction box, now a square stalactite. In fairness, this was under a leak, and most seepage is not this severe. And when someone is foolish enough to run EMT here, you get this. Believe it or not, this was installed on a rack away from the surface of the dam. The only other time I've seen this happen to EMT is when I've had to dig it up.

I got some CRC dielectric grease, which is just a silicone spray that is supposed to be a corrosion inhibitor. I get the feeling this stuff isn't up to the challenge. Does anyone have any experience with it? Also, someone was telling me about a type of desiccant they've used in damp-location j-boxes, but couldn't recall the name of the product.

Any ideas...?

-John
 
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Limited use idea, but it works...

Limited use idea, but it works...

This may sound silly, and it's certainly high maintenance...
but as you know the corrosive elements are in the moisture, in the air...

So reducing air flow in CCs and putting bags of silca-gel on bottom works well.
They do this when transporting stuff over seas. It's also fairly cheap.

Of course when you get the chance, go PVC or stainless 4x on everything...


Good Luck,

Doug S.
 
I wouldn't want your dam job.
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(Sorry I had to say it!)
 
This is a serious and dangerous problem .You have water with conductive minerals . this equipment must be replaced! I wouldnt want to see what the wires look like. bubble gum wont work on this one. You have to tell your employer that this equipment must be replaced before someone gets hurt you cant give him the bubble gum option !
 
 
I'm suprised any equipment was permitted to attach directly to the walls. I realize you're probably underground or pretty close to it, but the use of PVC seems to be the way to go in a humid, corrosive enviroment.
 
wow, that's some serious corrosion. nice pics. Its interesting to note that copper pipes shown in some of the pics have minimal oxidation. Clearly some of the equipment isn't up to the task based on the exposure its getting, but some of it is doing rather well. I'm sure your employer isn't in a position to start replacing everything, you are probably going to be in a position of picking the worst (and most iminently dangerous) items, and battling for replacement of those and picking what will work based on the conditions in those (worst) areas. jmshio
 
The reality is many utilities are allowing their infrastructure to degrade until the cost of revenue losses outweighs the cost of a proactive replacement program. Welcome to utility deregulation. Heck, it worked great for the airlines, didn't it?
 
I've not used this, but a customer was telling me about it and swears by it.

http://boeshield.com/index.htm

The formulation, based on a unique combination of solvents and waxes, is designed to penetrate metal pores and dissolve minor corrosion, then leave a resilient waxy coating that lasts for many months.

We began by successfully introducing Boeshield T-9? to the tough saltwater marine market for lubricating and protecting all metals. It works well on engines and deck hardware as well as electronics, batteries and wiring connections. It is non-conductive and will not cause short circuits.
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You may want to look at PVC coated conduit or PVC as mentioned earlier. In addition PVC enclosures fiberglass and SS enclosures. Also look at stand off's to keep equipment of the walls and coated armored cable seems they are using liqitite. Like the receptacle in the first picture.
 
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