Type MC cable provides an effective ground-fault current path and is recognized by the NEC as an equipment grounding conductor when it contains what?

Type MC (Metal-Clad) cable is designed to provide additional safety in electrical installations by offering a reliable path for fault currents, which is essential for safe operation and protection against electrical faults. The National Electrical Code (NEC) permits the use of the metal armor of the MC cable as an effective equipment grounding conductor, provided that the cable contains either an insulated or uninsulated equipment grounding conductor.

This means that the inclusion of either type of grounding conductor enhances the cable's ability to safely handle ground fault currents, reducing the risk of electrical shock or fire in the event of a fault. Using an insulated grounding conductor can provide additional protection in terms of preventing corrosion and electrical tracking, while an uninsulated conductor is directly in contact with the metal sheath which allows for quick dissipation of fault currents.

The flexibility in having either type of grounding conductor ensures compliance with safety codes and enables installations to be efficient without sacrificing safety standards. Therefore, the option stating that MC cable contains an insulated or uninsulated equipment grounding conductor accurately reflects the NEC's requirements for effective grounding practices in electrical systems.