What is the standard back time of Batteries in non alarm condition and in alarm condition?
Depends on if regular system or voice evac:::
For a basic fire alarm system that uses primary power with batteries only as secondary power, the battery capacity must be sufficient "to operate the system under quiescent load (system operating in a non alarm condition) for a minimum of 24 hours" and then still be able to operate "all alarm notification appliances" and all other connected loads for a period of five minutes. The code specifies that the net capacity be based on two different demand rates (quiescent and alarm) for two different durations (24 hours and 5 minutes).
Emergency communications systems (ECSs) used for mass notification or for in-building fire emergency voice/alarm communications service have the same 24-hour quiescent load requirement but require 15 minutes of full-load alarm capacity. This is because these systems are usually operated for longer periods during an emergency. They sometimes may be used for 30 - 60 minutes, but only under partial load as announcements are made to certain floors. They might then be called upon to operate under an increased or even full load for some period. The code requirement for 15 minutes of full load should be evaluated by the system designer in conjunction with a risk analysis to determine if a larger capacity should be provided.
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