Around 50,000 bees have been rescued from an electricity substation near Fakenham.
Engineers discovered the colony in a wall cavity of a brick building near Hempton.
It is believed that the bees had been settling into the wall for the last few years, making honey as the colony grew.
Specialist bee rescuer Gary Hipperson was called in to help.
The rescue took all day due to the area having a problem with bee disease, so biosecurity measures were taken to ensure the bees' safety.
Mr Hipperson took two bricks out of the wall from the outside to check out the size of the colony.
He cut out the individual honeycombs by hand, moving bees out of the wall into a collection box.
He said: “It was a large colony and a difficult rescue because of the position of so many in a small building.
"I am pleased we were able to save and rehome the bees. We always do everything we can to save them.”
Mr Hipperson took the colony back to Heath Farmhouse in Great Bircham where they were treated and put into quarantine for 76 days.
At the end of their quarantine, the healthy colony will be moved to nearby organic farmland where they can live happily and produce honey.
Heather Patrick, environmental adviser at UK Power Networks, said: “When we find honey bees living in a substation our first approach is to try to just leave them and put up signs to warn staff of their presence.
"If they do pose a hazard we try to find a beekeeper who can rehome them.
"I’m so glad that when these bees started to cause concern, the local field engineer was determined to protect them and found a beekeeper who successfully extracted them and will give them a new home."
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