Earthing rectangular tape in cable trench

[MikiBg]

Hi all!
I haven't found a clear recommendation about this issue, so I'm asking you about it...
Earthing tape with rectangular 30x3.5mm cross section shall be laid down in cable trench, as additional earthing on WWTP.
Is it better to laid it above or bellow cables? Some say that tape placed above cables will protected them against lightning strike. Not so sure about it, and besides, in this case, cable trench is within protected area of LPS. On the other side, bigger depth will decrease earthing resistance of the tape, but not significantly.
What side of cross section (longer or shorter one) shall be laid parallel to surface?
Does the way of laying remains the same if earthing tape shall form a closed, four sided belt?
Hope someone will answer me, with arguments...
Regards,
Miki

 

[MikiBg]

It's below,not bellow cables

 

[jghrist]

I don't think it makes much difference performance-wise for the grounding system. I'd lay the earthing tape above the cables because if someone goes digging in the area, they'd hit the earthing tape first and they may stop digging. It would cause less disruption to dig into the earthing tape and it would be easier to repair.

I'd lay the tape long side horizontal. Laying it vertical would be a pain in the a** to get right without bending the tape over either while laying it or backfilling. Especially if you require compacting the backfill. Contact area with the earth is the same either way. Laying as a closed loop wouldn't make a difference. You'd have to fold the tape at the corners if the long side was horizontal. Either that or make a connection at the corners.