9.) The non-bonding of metal raceways containing grounding electrode conductors. This problem is more common in dwelling unit installations than with commercial or industrial installations.
Section 250-92 (a), (3) requires that any metallic raceway or armor enclosing a grounding electrode conductor, that runs between the service equipment and the grounding electrode, be bonded on both ends. Section 250-64 (e) also requires that metal enclosures that are not physically continuous, from cabinet or equipment to grounding electrodes, be made electrically continuous on both ends by bonding to the grounding electrode conductor.
Example: a dwelling unit has a meter socket installed on the outside of the building. A number six copper grounding electrode conductor has been run from the grounding lug in the meter socket to the first ground rod located below the meter socket. The conductor has been run in EMT for physical protection. The EMT is attached to the bottom of the meter enclosure with a connector and standard locknut and runs down the outside wall to just above grade. The grounding electrode conductor runs out of the open end of the EMT sleeve and attaches to the ground rod. In this situation, the grounding electrode conductor could have been attached to a bonding bushing on each end of the raceway. This is one method that would meet the requirements of Section 250-92 (a), (3). If Rigid Non-Metallic Conduit (PVC) is used to protect the grounding electrode conductor bonding of the raceway is no longer an issue.