EMT burial gravel

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euclid43

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I ran emt on the perimeter of a house, and took a chance by covering with gravel. Underneath is a wee liner.

Inspector failed me because he considered it a burial. I told him that I can uncover it and it would be ok.

I know that this only pertains to emt being in contact with corrosive material.

Can someone give me a rating (1-10) of how outlandish this inspector is, or do I need to learn something?
 
Well I read 358.10 to say that emt can be direct buried when it is protected from corrosion. I don't see it giving leeway if the soil is not corrosive. On top of that it must be protected from corrosion and judged suitable for the condition. Well you know who the judge will be. :)
 
euclid43 said:
I ran emt on the perimeter of a house, and took a chance by covering with gravel. Underneath is a wee liner.

Inspector failed me because he considered it a burial. I told him that I can uncover it and it would be ok.

I know that this only pertains to emt being in contact with corrosive material.

Can someone give me a rating (1-10) of how outlandish this inspector is, or do I need to learn something?
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If your EMT wasn't corrosion protected, the inspector was correct IMO.
 
chris kennedy said:
Isn't all EMT corrosion protected these days? All be it maybe a febile attemt by the manufacture, but I was under the impression it was???
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Not according to UL - 2011 UL White Book, category: FJMX - Electrical Metallic Tubing.

"In general, galvanized steel EMT in contact with soil requires supplemental corrosion protection."

To answer the OP - NO, the inspector was not off base.
 
Here is what says about it.

Galvanized steel electrical metallic tubing installed in concrete on grade or above generally requires no supplementary corrosion protection. Galvanized
steel electrical metallic tubing in concrete slab below grade level may require supplementary corrosion protection.

In general, galvanized steel electrical metallic tubing in contact with soil requires supplementary corrosion protection. Where galvanized steel electrical metallic tubing without supplementary corrosion protection extends directly from concrete encasement to soil burial, severe corrosive effects are likely to occur on the metal in contact with the soil.

Galvanized steel electrical metallic tubing that is provided with a metallic or nonmetallic coating, or a combination of both, has been investigated for resistance to atmospheric corrosion. Nonmetallic outer coatings that are part of the required resistance to corrosion have been additionally investigated for resistance to the effects of sunlight.
Click to expand...
 
As wonderful as the "White Book" may be, it's not the 'law,' by any stretch of the imagination. Even if it were, please note the use of such terms as "may" and "in general;" one can drive a circus train through those qualifiers.

Returning to the OP ... not clear is the depth, and what is a 'wee liner.' It is possible that the OP is saying that he laid the pipe atop one of those landscape fabrics gardeners use to prevent weeds from sprouting, then just has a scattering of gravel over it. As such, I would consider this as comparable to using bark or mulch, and allowed; after all, if we can bury junction boxes that way, why not pipe?

I guess you can say there's "burying," and then there's "BURYING."

Laying the pipe atop the ground begs the question of how to secure it.

I do think that the corrosiveness of the specific location has relevance; Article 110 requires our methods to be suitable for the environment. As I see it, this general provision trumps any later, specific permissions granted to specific wiring methods. The method has to be able to survive the actual circumstances.

Now, let's look at 'reality.' In my experience, buried EMT has always had the worst corrosion at those points from 4-6" below grade. Those parts of the run below 12" have shown rather little corrosion. My theory is that deeper soil is packed tightly enough to exclude oxygen- which is necessary for corrosion to take place. Looked at in this perspective, laying the pipe on the surface is a very poor choice, and a light covering won't help matters at all.

Carrying the example further, I believe it is the way pipe-wrap tape keeps air away from the pipe that makes it so effective at protecting the pipe. Were the OP to wrap his EMT, I expect it would last a long time. Sure sounds like 'supplimental protection' to me.

I would probably prefer a different method than EMT to be used, but it's a design choice. I also am wary of this 'light covering is not burial' concept; it's something that begs for abuse.

All that lacks to make this a real discussion headache is to have the OP run romex in the pipe :)
 
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