Which device provides limited overcurrent protection in addition to the branch circuit's overcurrent device?

The supplementary overcurrent protective device is designed to provide limited overcurrent protection in addition to the primary overcurrent protection provided by the branch circuit's overcurrent device, such as a fuse or circuit breaker. This additional layer of protection can be particularly important in applications where specific equipment may require more than the standard protection that a branch circuit device can provide.

For example, supplementary devices are often used for equipment that is fed by an existing branch circuit to prevent damage to that equipment under overload or short-circuit conditions. They protect against smaller current surges or specific fault conditions that may not necessarily be addressed by the larger branch protection. It usually has a rating that is lower than that of the branch circuit protective device and is installed for protection of a specific load, which distinguishes it from standard overcurrent devices.

In contrast, the other options like a fuse and a circuit breaker serve as primary overcurrent protection devices, which are designed to interrupt the circuit in the event of overloads or faults. A surge protector, while it offers protection against voltage spikes, does not provide overcurrent protection in the same manner as a supplementary device. Therefore, the supplementary overcurrent protective device is the correct answer as it specifically addresses the need for additional protection while working alongside the primary over