Cutoff Of Electricity, Power Cut
noun, verbal noun
When you halt electricity you experience a power outage. Makes sense. When the electricity stops you don't have any more power.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
Why do I keep flipping light switches on and off if I know that there is still a power outage.