Underground Duct Bank and Frost Line

[faresos]

I was told the underground ductbank needs to be below frost line.

1. Where is the requirement came from?
2. How critical to follow this requirement?
3. What is the rational for this requirement?

I?m working on a project that the frost line is approximately 60? .

Thanks,

 

[don_resqcapt19]

I would expect that it is a design spec. Two reasons come to mind. To pevent damage from the frost heave that can occur if you are not below the frost line and to prevent the water from damaging the conductors when it freezes and expands by 10%.

 

[eHunter]

I was told the underground ductbank needs to be below frost line.

1. Where is the requirement came from?
2. How critical to follow this requirement?
3. What is the rational for this requirement?

I’m working on a project that the frost line is approximately 60” .

Thanks,

Reference:
http://forums.mikeholt.com/showthread.php?t=110737

http://forums.mikeholt.com/showthread.php?t=88753

http://en.wikipedia.org/wiki/Frost_heaving