From which power source are fire protection items powered?

Fire protection items on the PSA Airlines Canadair Regional Jet are powered from the DC Emergency Bus. This bus is specifically designed to provide power to critical systems in the event of an electrical failure. Fire protection systems, which include alerting mechanisms and suppression systems, are essential for safety and must remain operational regardless of the aircraft's power supply status.

By using the DC Emergency Bus, these systems ensure that they can function independently from the main power sources, which could potentially be compromised in an emergency. This design philosophy enhances the aircraft's overall safety, as it allows for the continuation of fire protection capabilities even if there are failures in the normal power supply routes.

While other buses in the aircraft, such as the Main Bus, Battery Bus, and AC Bus, serve various functions, they do not specifically provide the same level of redundancy for critical safety systems like the DC Emergency Bus does. This makes the latter the appropriate power source for fire protection items.