For a grounded conductor to be used for grounding at a separate building supplied by an existing feeder, which must not be bonded to the grounding system?

In order to maintain the integrity of the grounding system in a separate building supplied by an existing feeder, continuous metal paths, such as metallic conduit or raceways, should not be bonded to the grounding system. This is primarily because bonding these paths can create parallel paths for the return currents, which can lead to safety hazards and increase the risk of electrical shock.

Utilities and the National Electrical Code (NEC) emphasize the importance of keeping grounding systems isolated and properly segmented to avoid unintended currents traveling through unintended paths. Continuous metal paths are intended to provide physical protection for electrical conductors and should remain separate from the grounding system to ensure that they do not contribute to or interfere with the grounding integrity.

By keeping the grounding paths clear of these continuous metal paths, the grounding system can function correctly, ensuring the safety and effectiveness of grounding and bonding practices at the facility.