Power Failure planned and Unplanned
What are you trying to address through this SOP?
Are you going to provide the necessary actions that must taken following a power failure?
First and foremost thing to do is identify the purpose of the SOP, followed by the scope, and the rest can be like defining what is planned and unplanned power failure.
The other things to consider are communication strategy, and the procedure it self.
For writing a Power Failure SOP it is important to identify the Critical and Non-Critical Equipment/Systems that would be impacted. Most importantly, HVAC systems, CTUs, WFI Systems, Server Rooms, etc. should be considered while assessing the impact. Other systems include Life Safety Systems such as Fire Safety Alarms, Sprinklers. Also, you hack to make sure that IT infrastructure is back online. Most servers rooms and IT equipment can be on UPS for a short duration before Emergency Generators turn on.
Let me know if you any questions.