UK Power Networks (UKPN), who manage the national grid, say an issue on a high voltage overhead line has caused the cut.
As well as Sheringham and Cromer, its also affecting Holt, West Runton, Overstrand and Roughton.
The UKPN website said: "We are investigating a high voltage overhead electricity line fault which caused a power cut in the local area.
"We're sorry for any disruption this may be causing you. We estimate the power will be back on between 5-6pm."
Power had been restored to most of the affected homes by 5pm, though dozens remained cut off.