Negative terminal strip corrodes rapidly 1

[zaphod1]

Hi, I thought this might be the best place to begin my quest. We have an electrical room in a waste-water facility that stays relatively clean and dry- yet quite often (monthly) there is a growth of a white, almost calcium looking, substance that covers all the terminals that are common with the negative of a 24Vdc power supply. The power supply is a standard 120Vac/24Vdc switching supply. Does anyone have an Idea?
Thanks

 

[StewPad]

Congratulation, you made Aluminum oxide!
So take your Acid batteries out or vent the room.
And also use a dust mask the next time you work on the BUS.

 

[zaphod1]

Thanks for the response- but to clarify- there are no batteries in this room or in this system.

 

[StewPad]

No UPS or any other chemical tank nearby?
(Alum, pH buffer, agglomeration solution)

 

[zaphod1]

Nope, nothing but a very foul odor. (it's a waste water treatment plant). That being said- I guess there is a possibility of fumes from the process entering the room, but this is the only thing that appears to be affected.

 

[zaphod1]

One additional thing- all copper turns black in the panels very quickly. There is some new wiring that was added late this summer that are already black.

 

[StewPad]

Weird, so just blame the negative environment

 

[StewPad]

Take a second look and look for HNO3 solution.
Is the room located in a low elevation point?

As a preventing act add a small blower that will induce fresh air from a high elevation.

 

[Compositepro]

Waste waster. Rotten egg smell. Hydrogen sulfide reacts with copper to form black corrosion and aluminum to form white corrosion. Humidity is also a requirement.

 

[DRWeig]

Good call by Compositepro.

Been there, seen that.

Good on ya,

Goober Dave

 

[zaphod1]

Yes that was a good response- I am sure that H2S explains the problem- however it leads to other questions- Why is it white corrosion on copper terminals and why only the negative terminals?

 

[StewPad]

Two words: Cathodic protection