GRC elbows in direct contact with earth

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jayeomage

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NEC 344.10 (B)(1) can be interpreted that RGS, SS, and red brass all need additional corrosion protection for all the areas indicated; or it can be interpreted that RGS, SS, and red brass only need the additional protection where subject to "severe corrosive influences". Has anyone else experienced an interpretation issue on this?
 
RMC can be installed in normal soil conditions without added protection. The added protection is required for areas of "severe corrosive influences".
 
hardworkingstiff said:
How is "severe corrosive influences" determined? Anyone know?
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One digs up the trench and looks to see if the Rigid is still there. If only conductors are left, the soil is really corrosive. ;):grin:



Sometimes the soil may not have to be really corrosive. I have seen many times where the Rigid is corroded as it leave a concrete/cement foundation wall and enters the soil...completely corroded away.
 
Corrosion Protection and Coatings

Galvanized rigid steel conduit installed in concrete does not require supplementary corrosion protection.
Galvanized rigid steel conduit installed in contact with soil does not generally require supplementary corrosion protection.
In the absence of specific local experience, soils producing severe corrosive effects are generally characterized by low resistivity (less than 2000 ohm-centimeters).
Wherever ferrous metal conduit runs directly from concrete encasement to soil burial, severe corrosive effects are likely to occur on the metal in contact with the soil. ...
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The above is from the UL Guide Information for Rigid Ferrous Metal Conduit, DYIX
 
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