More than 120 people had to go without power for more than seven hours in Leavesden today.
UK Power Network confirmed that an underground cable fault meant that 37 people along Briar Road and Fern Way were without power from 3.39 this morning.
But after arriving to trying and solve the problem, UK Power Network had to cut power to an additional 86 customers to enable their "engineers to work safely on the electricity network."
Electricity supplies were returned to normal at 11.50am.
Jennifer Davis, press officer for UK Power Network, said: "We would like to thank customers for their understanding while we worked to return their electricity supplies and apologise for any inconvenience."