Fifteen homes were left in darkness when a fuse box exploded, sending debris and metal flying.
The fault affected power supplies in the Dollis Valley Estate throughout Sunday, leaving families without heating and electricity.
Thieves broke into a front garden in The Ridge and tampered with the box in January, causing a similar problem.
Laura Taylor, who has lived in The Ridge for seven years, said: “I was in my bedroom when I heard a noise like a bomb had gone off. The fuse box had exploded. Debris and metal hit my window – I was terrified.
“I don’t think it was fixed properly. I just feel completely and utterly shocked.”
The 24-year-old contacted Barnet Homes, which manages her property, and an engineer from UK Power Networks was sent to investigate the problem.
A spokeswoman from UK Power Networks said: “The equipment, which was part of our low voltage underground cable network, had been made safe by one of our engineers on January 5 when the original incident happened.
“However another fault occurred on February 23, interrupting power supplies to 15 customers. Work carried out in the area has enabled us to disconnect it completely to prevent further faults.”
The ground outside Miss Taylor's home has been dug up as work continues to fix the problem.