PHILADELPHIA — Nearly 15 years after Pennsylvania set electricity deregulation in motion, rate caps are set to expire for four of the state’s largest utilities on Jan. 1 — a prospect that once set fear into the hearts of nearly 5 millions customers affected.

But the anticipated rate spikes for customers of Peco Energy, Allegheny Power, Metropolitan Edison and Pennsylvania Electric aren’t expected to be nearly as painful as once expected, thanks to a slow economy and the growing natural gas industry across parts of North America.

“Rate caps are coming off at a time when energy prices across the economy are pretty reasonable,” said Irwin “Sonny” Popowsky, the state’s utility consumer advocate. “For better or worse, we took our time here in Pennsylvania. I think the transition has been reasonable.”

Rates are given in cents/kilowatt hour, and a difference of a cent can equal about $10 a month for a residential customer who uses about 1,000 kilowatt hours a month. The coming hikes at the four utilities will affect about 60 percent of the state’s customers.

Met-Ed customers will see a rate increase of about 2.2 percent, to 8.3 cents/kilowatt hour; Penelec customers will see a 16.6 percent increase, to 7.03 cents/kilowatt hour; Peco customers will see a 5 percent increase, to 9.92 cents/kilowatt hour; Allegheny Power customers will see a 4 percent increase, to 7.12 cents/kilowatt hour.

Those increases are much less onerous than what could have been if natural gas prices were higher. As recently as the summer of 2008, the price for natural gas was as high as $13 to $14 per 1,000 cubic feet, but those figures are down to about $4 per 1,000 cubic feet now.

Right now, the only major utility competition is shaping up in the Philadelphia area, where 17 electric suppliers are making offers to customers, Pennsylvania Public Utility Commission spokeswoman Jennifer Kocher said.

Energy companies are wooing potential customers through mail, billboards and TV ads, while the PUC and the state’s consumer advocate are posting competitive offers online for customers to compare. The PUC has a website for consumers at www.papowerswitch.com.

Customers do not have to switch. Even if they do, they will still get their bills from the default electric providers, which remain in charge of maintenance of the lines and distribution of the electricity; but a different company will actually be providing the power.

Last year, nearly 500,000 of PPL’s 1.4 million electric customers in Pennsylvania switched when PPL’s rate caps expired.

Customers should pay close attention to their options and look for ways to save as the competitive market grows, said Jim Cawley, chairman of the PUC.

“Shopping will become more and more accepted,” he said.