Brian is right. I'd call it an "electrical switchboard" or just "switchboard". Circuit breaker can be simply "breaker" if you want.
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Sometimes the reason is not what you think.Sometimes telling someone what the problem cause is can be misleading. Sometimes you can just explain things you know & let the expert analyse the cause.
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The power went off suddenly.
We are without power.
We have a black out now.
We need someone to fix this, ...promptly, emphasis as you see fit. :)
If you blew a fuse or a breaker, there was probably a reason. The reason is probably not in the switchboard. Expect questions about electrical things in your office. :)