When is a conrete encased duct bank required?

[cyriousn]

I may be totally missing something here but I cannot find a code reference to the requirement for concrete encased duct banks? I can see information about depths but nothing about when they are actually required....under roads? medium/high voltages?

 

[iwire]

Never by the NEC as far as I know.

Often an engineering specification.

 

[pete m.]

Not sure that you will find any requirement for a concrete encased duct bank in the NEC. I'm used to seeing that as part of job spec's.

Pete

 

[cyriousn]

Thanks guys.