×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Grounding Grid Placement

Grounding Grid Placement

Grounding Grid Placement

(OP)
Is it necessary to place the Grounding Grid below the frost line of the soil to ensure the resistivity of the soil will remain constant and also to prevent heaving?

Thanks in Advance!

RE: Grounding Grid Placement

I'm in canada, and the code keeps the ground grid between 6" and 24".  I beleive if you put it below the frost you may have problems with step-touch potentials.  I've dug up a couple of stations installed in this fashion and not seen damage due to frost.  Ground rods are installed through the frost, and I haven't personnally seen them pushed out, but perhaps others have.  I beleive it is important to get the rods below the frost level for the reason you've stated, but not the grid.  I would suggest a review of IEEE 80, "IEEE Guide for Safety in AC Substation Grounding".

RE: Grounding Grid Placement

I would agree with gordonl.  The ground rods must be long enough to be below the frost line.  In Minnesota, we used 30 foot ground rods.   The portion above the frost line is not useful in reducing impedance to earth when the ground is frozen.

The grounding grid, however, should probably be relatively close to the surface to provide adequate step/touch potential reduction.  The frozen soil has a very high resistance.  







Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources