Site Grounding Inspection Points

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Site Grounding Test Conditions

Site Grounding Inspection Points

• Verify that ground rods are copper-clad steel not less than 0.625” diameter and a minimum of 8’’ length.
• Verify that CDOT approved other ground rod type if copper-clad steel was not used.
• Verify that grounding electrode conductor is not less than #6 AWG.
• Verify that braided ground straps consist of non-insulated tinned copper flat braid wire not less than 0.5” width and 0.07” thick (for bonding between a cabinet frame and busbar only).
• Verify that insulated grounding electrode conductors are Type THWN with green jacket color.
• Verify that grounding electrode conductor was installed in a continuous run without splices or joints.
• Verify that connectors are exothermic weld for below grade connections and areas exposed to moisture.
• Verify that connectors are UL listed compression connectors for above grade installations and where safety dictates.
• Verify that ground bus is copper bar stock with stainless steel stand-off brackets and mounting hardware.
• Measure resistance of the first installed grounding electrode and test with earth ground resistance tester (3-point fall of potential method).  If results exceed 10 ohm, a second grounding electrode needs to be installed.
• Verify that second grounding electrode is at least one electrode length away from the first grounding electrode and connected via bonding jumper.
• Measure grounding electrode system resistance with earth ground resistance tester (3-point fall of potential method).  CDOT will accept 25 ohm or less after two grounding electrodes have been installed.
• Verify that oxidation and antioxidant compound was used at connection points to ground bus.
• Verify that stainless steel hardware was used and torqued to a specific value based on hardware grade, material, and size.
• Verify that connections to ground bus utilize a flat washer and Bellville washer for each bolt.
• Verify that all exothermic welds have slag removed.
• Verify that testing is performed prior to connecting to utility ground.