I deal with a lot of remote offices located in parts of the world where the local grid power supply is unreliable.
Power can go off anytime with no warning, with outages ranging from minutes to days
Power fluctuation is wild, with spikes and brown outs
Currently the offices will have some or all of the following:
A generator, with an inverter, or some sort of manual switch
A big UPS or battery array connecting a number of devices
Several smaller APC UPS with computers attached
Low cost Voltage Regulators sometimes connected between mains and UPS or device.
I know that each of these things needs to be appropriately rated for the equipment to which it is connected (although I am not sure how to calculate the correct rating).
The offices will generally have the following equipment (in varying quantities):
some sort of internet connection device (VSAT router, ADSL modem, WiMax router)
Cisco ASA 5505 firewall
a bunch of PCs
printers
one server
I don't seek to replace the advice of an electrician, but in some of these locations they only answer the questions you ask them, so I need to make sure I have enough understanding of the essentials to protect equipment from damage, and possibly get through some power cuts.