A data center earthing system has to do three jobs at once: clear faults safely, keep touch and step voltages within limits, and give sensitive IT equipment a low-impedance reference at high frequency. Those requirements pull in different directions, and in the Kingdom the soil makes the compromise harder.
Start with the soil, not the drawing
Wenner four-pin surveys across Riyadh, Jubail and Dammam sites routinely return apparent resistivity between 150 and 1000 Ω·m, with dry surface layers over more conductive strata. A two-layer model derived from the survey is what makes an IEEE 80 calculation meaningful; without it the grid is guesswork.
One bonded system
The single most common specification error we correct is a request for an isolated ‘clean earth’ for IT loads. Isolated earths create potential differences during faults and lightning events — exactly the condition that destroys equipment. Bond everything to a common earthing network and control noise through the signal reference grid and cable management instead.
Grid and signal reference design
- Perimeter grid with buried horizontal conductors, exothermically welded at every crossing.
- Deep-driven or drilled electrodes where the resistive top layer must be bypassed.
- Signal reference grid on a 0.6 m mesh under the raised floor, bonded to rack frames.
- Main earthing bar per electrical room, with labelled and testable connections.
- Bonding of containment, busway, piping and structural steel at defined intervals.
Setting a realistic target
Aramco, SEC and hyperscale client specifications differ on the resistance figure they will accept. The correct approach is to calculate the value required for safety and equipment protection, agree it in writing, then design the electrode array — including enhancement material where resistivity demands it — to reach it in the dry season, not the wet one.