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#103308 - 06/25/02 07:42 PM Corroded Conduits Here  
Joe Tedesco  Offline
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA
[Linked Image]

This picture was taken in Las Vegas last month, and shows were the conduits are corroded at the point of contact with the earth.

They were wrapped with tape, but it looked like there was not enough provided.

This is a common situation around the country, and could use a technical reply from someone who may know the reasons why this happens?

I will also search for that information in the UL Directory "White Book" and add comments later.

[This message has been edited by Joe Tedesco (edited 06-25-2002).]


Joe Tedesco, NEC Consultant

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#103309 - 06/25/02 10:44 PM Re: Corroded Conduits Here  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
I don’t think they salt roads or alleyways in Vegas—at least not very often.

Some years ago this was discussed in EC&M Magazine. With galvanized, It is a potential problem at the transition between air and soil; soil and concrete; and concrete and air. Worse yet is bare aluminum conduit in concrete—it turns to powder.


#103310 - 06/25/02 11:32 PM Re: Corroded Conduits Here  
nesparky  Offline
Member
Joined: Jun 2001
Posts: 642
omaha,ne
This is old fashoned corrision. It is not something that can be stopped - slowed down- but not stopped. The service taught that a galvanic cell simular to a battery- anode-cathode,elecrolite, and path for current flow will return any metal back to it's natural state.
Dissimular metals some of those are in the ground (different than the conduit) set up the anode vs cathode, contact with earth= current path,water = electrolite, together = galvanic corrision cell.
This is the reason I use PVC as much as possible in earth or concrete.

I saw some DOD web sites that had some good info on this, but don't have those URLs anymore.


ed

#103311 - 06/26/02 09:39 PM Re: Corroded Conduits Here  
HotLine1  Offline


Member
Joined: Apr 2002
Posts: 6,872
Brick, NJ USA
Had this situation a few times, made a determination that the corrosion started at a section that was field threaded. Another opinion we heard was "poor drainage" as may be evidenced by the pipe that resembles a downspout/roof drain near the corroded conduits. Question please; what type of "tape" was/is evident at the base area of the conduits??

We solve the situation with either PVC or PVC coated GRC if necessary.

John

[This message has been edited by HotLine1 (edited 06-26-2002).]


John

#103312 - 06/26/02 11:24 PM Re: Corroded Conduits Here  
Joe Tedesco  Offline
Member
Joined: Oct 2000
Posts: 2,749
Boston, Massachusetts USA


Joe Tedesco, NEC Consultant


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