Which of the following is more common in British English vs American English?
- Power cut
- Power outage
- Power failure
English Language & Usage Stack Exchange is a question and answer site for linguists, etymologists, and serious English language enthusiasts. It only takes a minute to sign up.Sign up to join this community
"Power cut" is certainly the most common in the UK, as seen in the comments. Lexico Oxford Dictionaries gives the phrase the "British" tag.
As for blackout being used as a term for a mass outage in the UK, the fairly recent mass power cut that affected the nation is indeed referred to as a blackout more often than power cut.
"Blackout" is also seemingly used to mean a wide-scale outage in the US, as shown in News as well.