For Class I circuits, where are overcurrent devices required to be located?

In Class I circuits, overcurrent devices must be located where the conductor that is being protected receives its supply. This is because the purpose of an overcurrent device, such as a fuse or circuit breaker, is to protect the wiring and components from damage due to excessive current. Placing the device at the point where the power is supplied allows for immediate interruption of current flow in the event of an overload or short circuit, thus preventing potential damage to the entire circuit or system.

Positioning the overcurrent device directly at the supply point ensures that all downstream components and conductors are adequately protected, establishing a critical line of defense against electrical faults. This is particularly important in fire alarm systems, where safety and reliability are paramount, and ensuring that all parts of the system are properly safeguarded contributes to overall operational integrity.