Power sources for fire signaling systems in residences are typically limited by which component?

The correct answer focuses on the Type PLFA power supply because this type is specifically designed for fire alarm systems and adheres to the National Fire Protection Association (NFPA) standards. Power sources for fire signaling systems must ensure reliability and safety, and the Type PLFA power supply is tailored to provide the required voltage and current while complying with the safety regulations outlined in NFPA 72, the National Fire Alarm and Signaling Code.

This type of power supply is especially important because it is listed for the operation of fire alarm systems and has certain limitations and requirements that are not found in other types of power supplies. It is intended to provide power in a way that minimizes the risk to life and property during a fire event.

The other options represent components that may be used in various electrical systems but do not specifically pertain to the limitations imposed on fire signaling systems themselves. For example, battery backup systems are critical for maintaining operation during power outages, but they are not the primary limitation source as they are meant to supplement power supply continuity. Power transformers can convert voltages but do not have the same specialized characteristics necessary for fire alarm systems. The Type C power supply might be versatile and useful for different applications, but it lacks the specific certification and conditions critical