Electric and natural gas utility NStar is seeking an approval from the Massachusetts Department of Public Utilities to cut power supply rates by 10% due to falling natural-gas prices.

The new price is expected to save the average NStar customer about $5 a month compared to current rates and to be in effect between July 1 and December 31. Nearly 800,000 customers in the company’s service territory will benefit from these price cuts, the company said.

Tom May, chairman, president and CEO of NStar, said: “Our customers have seen the cost of electricity plummet since the highs of a couple of years ago. As everyone works to cut energy use through improved efficiency, we’re thrilled to pass on even more savings to our customers through lower prices.”

According to NStar, though delivery charges vary slightly by region, the basic service supply price for the company’s residential customers will drop from 8.88 cents to 7.98 cents per kWh.

As a regulated distribution company, NStar purchases electricity from suppliers and passes the cost directly to customers who are on its basic service supply rate. Customers who purchase electricity through aggregate buyers or directly from suppliers are not affected by this price reduction.