I have a situation where the specifications are asking for battery back up to be an integral part of the power supply units used to power Delayed Egress Devices. I have challenged the specifications with the following reasons.
NFPA 101 clearly states that
Section 188.8.131.52.1.1. - The delay of the delayed egress electrical devices shall deactivate allowing unobstructed egress upon actuation of the following :
1. Approved supervised automatic sprinkler system.
2. Not more than one heat detector of an approved supervised automatic fire detection system.
3. Not more than 2 smoke detectors of an approved supervised automatic fire detection system.
So this is clear that providing a battery back up in the power supply unit will be in contravention of the above as it will continue to power the device ( which is dangerous and impede quick escape ), until someone manually presses the device to initiate irreversible delay of 15 seconds or 30 seconds.
In addition the only items which truly need a battery back up would be sounders ( provided in the vicinity of the door opening ) and the exit signage.
Correct me if I am wrong .