Hertfordshire streetlight "error" admitted by council
Hundreds of streetlights are being left on during the day because contractors sent to repair them in the dark "thought they were working".
Hertfordshire council said 260 faulty lights had been reported but contractors were sent to fix them during the evening.
Seeing the lights on, they then assumed the units did not need repairing.
Opposition councillors said it looked like a waste of money but the council said it was not costing taxpayers more.
Conservative councillor Terry Douris admitted some lights had been left on "much longer than we would have liked".
"The crews went out to fix them when it was dark and, when they saw the light on, they thought the light was actually OK and that was an error," he said.
"It was a silly mistake. Everybody makes mistakes. We've put it right and it won't happen again."
In 2012, Hertfordshire's streetlights were switched off between midnight and 06:00 in a bid to save an estimated £1.3m a year and reduce carbon dioxide emissions by 30%.
The move was opposed by the Liberal Democrat group and leader Stephen Giles-Medhurst said leaving lights on was "not the right message to send out.
"A new contractor was appointed in October so it has taken the best part of nine months to unearth it as a problem," he said.
"Residents are very annoyed when they can see lights on all day long and then go home to find their residential streetlights have been turned off at night.
"They perceive it as a huge waste of money."
'Costs nothing more'
Mr Douris said lights left on due to faulty equipment were not costing the people of Hertfordshire "a penny more".
"The streetlights aren't on a metre, there is a different way of charging for the electricity they use so if they are on during the day it costs nothing more," he explained.
"Somewhere along the line it's the electricity providers who are paying."