How are fuses and circuit breakers required to relate to service equipment?

Fuses and circuit breakers are critical components of service equipment as they serve the vital function of overcurrent protection. They must ensure they interrupt the circuit load as designed, meaning they need to prevent excessive current from flowing through the circuit, which could cause overheating, fire, or damage to electrical devices. This requirement aligns with the NEC to ensure safety within electrical installations.

When properly installed, fuses and circuit breakers effectively disconnect the power supply under fault conditions or during overload scenarios, thus safeguarding both the installation and the equipment connected to the service. This functionality is an essential aspect of electrical safety that must be adhered to in line with the NEC guidelines.

The other options do not reflect the necessary requirements or safety standards outlined in the NEC. For instance, placing protective devices anywhere on the equipment, suggesting they are optional if labeling is clear, or limiting their use to residential settings does not align with the code requirements regarding the structural integrity and operational principles necessary for effective overcurrent protection.