Table 300.5

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mshields

Senior Member
Location
Boston, MA
Table 300.5 defines fill requirements for direct buried conduit. What are the rules when that conduit is encased in concrete. For example, if I use RGS I can be as shallow as 6 inches. What about PVC concrete encased?
 

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
The table is set up to use the part which affects your install. PVC can be installed at 18" below grade where there is no vehicular traffic and 4 inches when it is below 4" thick concrete with no vehicular traffic. There are other possibilities also.
 

mshields

Senior Member
Location
Boston, MA
hmm

hmm

first of all - thanks for taking time on a Sunday to answer this!!!

Now, I had looked and am looking at Column 3 right now, and none of these categories quite fit, it seems to me, a concrete encased duct bank. UNLESS, you use the Under 4 inches of contrete category.

Should I infer from that that if I want to use a comlete concrete encasement, the top of that should be 4 inches thick?
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
If the pvc has 2" of cover over the top of the pvc then 12". If there is 4" of concrete and no vehicular traffic then 4"
 
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