The statement that exposed structural metal in the area served by a separately derived system must be bonded to the grounded conductor of each system is true.

The statement that exposed structural metal in the area served by a separately derived system must be bonded to the grounded conductor of each system is true.

• A. True
• B. False
• C. Not specified
• D. Depends

Answer: (B)

The key idea is that exposed structural metal should be bonded to the equipment grounding conductor of the electrical system, not to the neutral (the grounded conductor). The equipment grounding conductor provides a dedicated, low-impedance path for fault current to return to the source so protective devices clear the fault quickly. The neutral, while it is bonded to earth at the service or at a separately derived source, carries current during normal operation and is not the intended bonding path for structural metal. In a separately derived system, you still connect exposed metal to that system’s equipment grounding conductor. Bonding the metal to the grounded conductor (neutral) of the system would create a potentially energizing path on the metalwork during normal operation and faults, which is not how bonding is intended to work. So the statement is not correct because the required bond is to the equipment grounding conductor, not to the grounded conductor of each system.

The key idea is that exposed structural metal should be bonded to the equipment grounding conductor of the electrical system, not to the neutral (the grounded conductor). The equipment grounding conductor provides a dedicated, low-impedance path for fault current to return to the source so protective devices clear the fault quickly. The neutral, while it is bonded to earth at the service or at a separately derived source, carries current during normal operation and is not the intended bonding path for structural metal.

In a separately derived system, you still connect exposed metal to that system’s equipment grounding conductor. Bonding the metal to the grounded conductor (neutral) of the system would create a potentially energizing path on the metalwork during normal operation and faults, which is not how bonding is intended to work.

So the statement is not correct because the required bond is to the equipment grounding conductor, not to the grounded conductor of each system.