his item should set off alarm bells in more than 10,000--perhaps as many as 20,000--businesses and homes in Prince George's County. The county Department of Licenses and Permits has begun enforcing a local law requiring all the owners of burglar alarms to buy permits costing $10 a year.

Charles Deegan, acting director of the department, said yesterday that the permit requirement is part of an effort to reduce the number of false burglar alarms in the county, which has risen to an average of 196 a day. Most are triggered by weather, vibration, animals or people opening doors when an alarm's mechanism is turned on.

Under the law, every person who has a licensed burglar alarm in his home or business is permitted two false alarms a year at each registered location. A third false alarm may cost a $30 fine. A fourth alarm could result in a hearing and an order to get the mechanism repaired or to remove it.

"When [police officers] answer a false alarm and find the location is not licensed, they will leave off an application" for a permit, Deegan said. "We're not out to harass them."

Many of the estimated 10,000 to 20,000 alarms in the county either make wailing or clanging sounds to attract attention, while others are tied in to central monitoring stations operated by commercial alarm companies. To date, Deegan said, about 1,000 alarm owners have applied for licenses.

Theoretically, Deegan acknowledged to a reporter, the owner of an unlicensed burglar alarm could be cited and fined up to $200 even if it brought police to the scene of a real break-in. For now, he said, that kind of enforcement is not planned.