Equipment must be engineered and tested to operate properly at what percentage of its nameplate voltage?

The requirement that equipment must be engineered and tested to operate properly at a specific percentage of its nameplate voltage is crucial for ensuring reliability and safety in fire alarm systems. Operating at 85% of the nameplate voltage means that the equipment is designed to function effectively even when the supply voltage falls below its rated value.

This ensures that variations in voltage, which can occur due to fluctuations in the electrical supply or other factors, do not prevent the equipment from performing its intended function. In fire alarm systems, this is particularly important, as any failure in operation can lead to serious safety hazards.

Testing at 85% allows for a buffer, ensuring that the fire alarm system will still activate under less-than-ideal voltage conditions, thus enhancing the reliability of fire detection and notification during emergencies. Standards and codes often reference this percentage to guide manufacturers and installers in ensuring compliance with recommended practices for fire safety systems.