How many fuses are required in a three-phase four wire branch circuit with ground and neutral?

In a three-phase four-wire branch circuit, the basic setup consists of three phase conductors, one neutral conductor, and usually a ground conductor for safety. Each of the three phases requires its own fuse to protect against overload or short circuit conditions. Therefore, in a three-phase circuit, you need three fuses—one for each of the phase conductors.

The neutral wire in a four-wire system is not typically fused because it merely serves to provide a return path for unbalanced loads in the system, and its current-carrying capacity should be sufficient to handle the return current without needing additional protection.

The ground wire is also not fused, as its purpose is strictly for safety and equipment protection, grounding the system to prevent electrical shock or equipment failure.

Thus, in total, you would need three fuses for the three phase conductors to ensure proper protection in a three-phase four-wire branch circuit.