It’s that time of year again. The holiday season is in full swing which means people across the country will brave ladders and climb on roofs to hang festive lights and partake in the holiday cheer.

Unless you’re Clark Griswold from "National Lampoon’s Christmas Vacation," holiday lights themselves may not sound dangerous, but there's one thing in particular that is troubling to electricians.

Electrician Ken Sparrow, owner of highly rated Gibbons Electric in Arlington, Mass., says an alarming number of households are not equipped with ground fault circuit interrupter (GFCI) outlets, which are special electrical outlets that are installed in areas where there is a risk of electricity meeting water like in outdoor outlets and in kitchens and bathrooms.

"We do a 12-point safety inspection when we go to homes and we find a lot of outdoor outlets are not even on a GFCI, especially older homes," Sparrow says. "It’s very important."

GFCI outlets look similar to the traditional counterparts, however, they can be identified by the “test” and “reset” buttons on their face. They monitor the flow of an electrical current in a circuit, and when a ground fault occurs, the flow between the neutral and hot wires becomes unbalanced. Once there's a disturbance in current, the GFCI breaks the electrical circuit and shuts off the energy flow.

Electricians recommend GFCI outlets because they react faster than circuit breakers or fuses. These outlets not only prevent serious electric shock, but they also reduce the risk of electrical fires and prevent damage to appliances.

Pasquale Ceriello, field manager at the highly rated Brooklyn, N.Y. electric company Antonio Ceriello Electric Inc., agrees.

"All outdoor Christmas light installations should be fed from GFCI outlets," Ceriello says. "Additionally, the lights and any extension cords should be approved for outdoor use by the product manufacturer and should not be altered in any way. Outdoor lights not plugged into approved outdoor extension cords can potentially cause fires."

Fortunately for homeowners, installing a GFCI outlet is not a major project, but it should still be left to a licensed electrician.

Paul Harris, electrician and owner of Fairway Electric in Agoura Hills, Calif., says he gets many calls about installing GFCI outlets during the holiday season, and he makes a point offer the service when starting a job.

"We always ask during the course of any remodels, rewires or our new construction projects if holiday outlets will be needed in the landscaping and under the roof eves," he says.

Steve Berry, supervising electrician for highly rated The Connection Electrical of Chicago says he also sees an uptick in GFCI-related work during the holiday season.

"Ninety percent of the calls for Christmas light problems are GFCI outlet related, some are bad and some just need to be reset," he says.

Editor's note: The original version of this article was published on December 7, 2011.