Cover requirements for duct bank

[jsteed]

Several of us are having a discussion concerning the required cover over a duct bank. A colleague's email sums the discussion up best:

"We are trying to determine the minimum depth we can run a concrete encased 600 volt duct bank under a plant roadway. Article 300.5 and Table 300.5 address direct buried conduits and conduits with a concrete slab over top, but does not appear to address concrete encased ductbanks. One of my staff members understands from Table 300.5 the ductbank needs to be 24inchs deep under the driveway (although there is no column in the table for concrete encased conduit), whereas I had always understood concrete encased ductbanks could even be flush with the ground or driveway."

Opinions?

thanks
jim

 

[SEO]

Per table 300.5 under streets, highways, roads, alleys, driveways, and parking lots 24" is min depth to top of raceway for other than one and two-family dwellings. Concrete encased or not 24" in min.

 

[nakulak]

I suggest you run this by a civil engineer. The amount of heavy truck traffic and the integrity of the subsurface might be factors that you would want to consider.

 

[markstg]

Rebar in the ductbank is required, that is standard under roadways.