Bethesda, Md. ? An inexpensive device that detects wiring problems could prevent many of the 40,000 electrical fires that damage U.S. homes and kill 350 people each year, safety officials said Tuesday, urging homeowners to install Arc Fault Circuit Interrupters.

The device, also called an AFCI, cuts power when it detects electricity arcing from damaged wires. Homes with old wiring are especially vulnerable to this problem, which can occur when wires or cords overheat or are pinched by furniture, pierced by nails, frayed from age or gnawed by rodents.

“Without question, AFCIs are the most important safety innovation since the smoke alarm,” said Donald Bliss, president of the National Association of State Fire Marshals. “They should be installed in every home and installed now.”

AFCIs cost as little as $25, but the Consumer Product Safety Commission said installing one can be dangerous and should be done only by a licensed electrician.

While not officially recommending that all consumers use AFCIs, the safety commission said people should consider having them installed, particularly in the more than 50 million U.S. homes with wiring more than 40 years old.

With people buying bigger televisions and other large electrical appliances, older wiring can be pushed too far. Electrical arcing in damaged wiring can create temperatures high enough to ignite wood, paper and carpets.

Electrical fires cause hundreds of millions of dollars in property damage each year.