Under what condition is listed liquidtight flexible metal conduit (LFMC) acceptable as an equipment grounding conductor?

Under what condition is listed liquidtight flexible metal conduit (LFMC) acceptable as an equipment grounding conductor?

• A. When it terminates in unlisted fittings
• B. When it is protected by an overcurrent device rated above 60A
• C. When it is protected by an overcurrent device rated 60A or less
• D. When it is not connected to any fittings

Answer: (C)

Listed liquidtight flexible metal conduit (LFMC) is acceptable as an equipment grounding conductor when it is protected by an overcurrent device rated 60A or less. This condition is specified because LFMC is designed to provide a grounding path under certain constraints, primarily reliant on its ability to handle fault currents safely, which is significantly influenced by the rating of the overcurrent protection. When the conduit is protected by an overcurrent device rated at 60A or less, it ensures that in the event of a fault, the metal conduit can safely conduct the fault current without the risk of overheating or causing damage to the conduit itself or the equipment it is serving. This specific rating helps maintain safety standards and the integrity of the conduit as an effective grounding path, ensuring that it can handle the electrical loads and any potential fault conditions that may arise. In contrast, the other conditions would not sufficiently ensure the safe use of LFMC as an equipment grounding conductor. For instance, if the LFMC terminates in unlisted fittings or is protected by a higher overcurrent device rating, it could potentially compromise the grounding effectiveness and safety protocols required.

Listed liquidtight flexible metal conduit (LFMC) is acceptable as an equipment grounding conductor when it is protected by an overcurrent device rated 60A or less. This condition is specified because LFMC is designed to provide a grounding path under certain constraints, primarily reliant on its ability to handle fault currents safely, which is significantly influenced by the rating of the overcurrent protection.

When the conduit is protected by an overcurrent device rated at 60A or less, it ensures that in the event of a fault, the metal conduit can safely conduct the fault current without the risk of overheating or causing damage to the conduit itself or the equipment it is serving. This specific rating helps maintain safety standards and the integrity of the conduit as an effective grounding path, ensuring that it can handle the electrical loads and any potential fault conditions that may arise.

In contrast, the other conditions would not sufficiently ensure the safe use of LFMC as an equipment grounding conductor. For instance, if the LFMC terminates in unlisted fittings or is protected by a higher overcurrent device rating, it could potentially compromise the grounding effectiveness and safety protocols required.