Will power outage cause damages to iMac?

If you iMac was shut down and not sleeping it is unlikely that a power outage caused any damage. If there was a massive surge when the power went off or came back on it could have but that is not likely. A s long as there was no big spike or surge, a power outage is like pulling out the plug on your iMac.

But if the power outage occurred while you were using the computer it may suffer damage and you would definitely lose the updates to the file you were working on. To protect all my computers I have them connected to an APS Uninterruptible Power Supply (UPS). Then if the power goes off the UPS will power the computer and provide time for a safe shutdown.

patrick07124 wrote:

When the power went off and came back, the iMac was off and plugged in.

How can I know if a massive surge has happened?

Your iMac would not have come back on and perhaps other devices in your home would also have been damaged.

Does it still work?