Where shall disconnecting means be provided on a supply side of all carriage fuses?

The correct choice indicates that the disconnecting means for all carriage fuses should be accessible to other than qualified persons. This is essential for safety and compliance with electrical codes, as it ensures that individuals who may not have specialized training can operate the disconnecting means without risking harm or exposing themselves to hazardous conditions.

Accessibility is a critical consideration in electrical installations. By requiring that disconnecting means be accessible to the untrained public or personnel, it promotes safety by enabling emergency shut-off options to be accessible in case of an electrical fault or fire. Such accessibility helps ensure that backup measures can be taken swiftly without needing specialized knowledge.

While the other options describe locations where a disconnecting means might be found, they do not align with the requirement for accessibility. For instance, positioning it near a circuit breaker may not provide immediate access in emergencies, and placing it inside the service panel could be impractical for untrained individuals. Similarly, having the disconnecting means at the transformer, while feasible, could hinder access for those who are not qualified, risking delays in emergency situations.