UNIONDALE, N.Y. (CBSNewYork/AP) — Long Island Power Authority has overcharged its customers by $231 million due to a faulty formula it used to calculate charges for power that seeps from its electric grid.

WCBS 880 Long Island Bureau Chief Mike Xirinachs reports

Newsday reports that LIPA has begun returning $129 million of the money through incremental rate cuts spread over three years.

Beginning in April, customers will see an average $2.85 reduction in their monthly bill for the rest of the year, and $1.50 a month for 2012 and 2013.

LIPA approved a measure to change the way it calculates the charges at a meeting in January.

LIPA’s interim chief executive, Michael Hervey, says the company became aware of the “lost” power last summer.

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