In flexible metal conduit, is bonding of metal water piping and interconnected metal building framing required for separately derived systems?

Bonding of metal water piping and interconnected metal building framing is indeed required for separately derived systems, and this is primarily for safety reasons. Bonding ensures that any potential fault currents can safely travel back to the ground, reducing the risk of electric shock and ensuring proper operation of overcurrent devices.

Separately derived systems—those that originate from a source that is not connected to the electrical supply system’s grounding system—can pose increased risks if they are not properly bonded. Without bonding, there could be differences in electrical potential between the separately derived system and the bonded components, potentially leading to dangerous shock or fire hazards.

In addition, the National Electrical Code (NEC) mandates bonding to help ensure a low-resistance path for fault currents. This requirement is designed to minimize the risk of electrical shock to people and equipment by maintaining equal potential across bonded conductive materials.

Therefore, bonding is crucial in this context to ensure the safety and effectiveness of the electrical system.