Connecticut residents face spikes in electric bills next year if rate increases requested by the Connecticut Light and Power Co. and United Illuminating are approved.

United Illuminating -- its service area includes Fairfield -- is seeking to increase its average residential bills by $35 a month.

CL&P has filed a new rate increase with state regulators that would boost average residential bills by $18 a month. A previously filed CL&P rate increase request would add another $10 to average monthly bills.

The latest rate hikes, now pending before the state Public Utilities Regulatory Authority, would take effect Jan. 1.

"It's not good for ratepayers, particularly those on a fixed income," said John Erlingheuser, advocacy director for the state chapter of AARP.

Both utilities blamed the proposed rate increases on rising electricity costs and constraints in pipelines delivering natural gas to New England, and both advised consumers to conserve electricity.

"We're urging all CL&P customers to take advantage of our efficiency programs to help reduce their usage, tighten up their homes and keep energy bills down this winter," said Penni Conner, a senior vice president at Northeast Utilities, CL&P's parent company.

Attorney General George Jepsen said the standard rate increases filed Friday are "unwelcome news" for Connecticut consumers and represent rising prices in the electricity market.

"This increase in the standard service rate underscores the need for PURA to closely scrutinize and reject those portions of CL&P's distribution rate application that are more than just and reasonable," Jepsen said.

Jepsen is referring to a previously filed, $221 million CL&P rate hike request intended to upgrade and strengthen distribution equipment in anticipation of future storms. The increase would add another $10 to average monthly bills.

The attorney general has told PURA that CL&P's distribution rate increase -- a 20 percent hike -- is "excessive and unwarranted," and urged regulators to trim the request by more than $90 million.

Electric utilities make their money on the transmission or distribution side of the business, which involves delivering electricity to customers. The proposed standard rate increases are on the generation side, reflecting the cost of purchasing power from suppliers.

The utilities on Monday pointed out the proposed standard rate increases will not boost utility profits because increased purchasing costs are passed on to consumers.

CL&P, the state's largest electric supplier, is seeking to hike its standard rate to 12.45 cents per kilowatt hour, from 9.96 cents per kilowatt hour, a 20 percent increase.

The new rate means an average CL&P monthly bill, based on using 750 kilowatts of power a month, would increase by $18.

United Illuminating is seeking to raise its standard residential rate to 13.35 cents per kilowatt hour, from 8.66 cents per kilowatt hour, a 35 percent increase. The rate hike would increase average bills by $35 a month.

"We're always mindful of the effect these supplier increases have on our customers, particularly those who are facing difficult financial circumstances," CL&P's Connor said.

Pat McDonnell, senior director of conservation and load management at UIL Holdings Corp., which owns UI, also advised ratepayers to conserve power.

"To help our customers keep their bills in check and manage their budgets, we want them to know there are options to help them save money and reduce energy usage," McDonnell said.

Erlingheuser, the AARP advocacy director, warned third-party electric suppliers will simply "hug" new rates set by the larger utilities.

"The third-party guys look good and could give a decrease, but they don't," Erlingheuser said. "They hug the standard offer."

He advised consumers to closely review third-party deals.