Smoke detectors with special features can help homeowners meet unique needs for fire safety.

Q. I'd like to have new smoke detectors in my home but would prefer they be wired to the house current so I wouldn't have to worry about battery failure. Are detectors of this type available? - R. Scullion.

A. Smoke detectors that can be connected directly to household wiring are available. Mike Gipson, product manager of First Alert, a leading manufacturer of detectors, said "hard-wired" detectors were used mostly in new homes and were installed by contractors because of the wiring required. Do-it-yourselfers who understand electrical wiring can install them without difficulty, however.

Although a hard-wired detector won't have battery failure, there can be a lapse in performance because of a power outage. For that reason, many hard-wired detectors include a battery backup that takes over if the main power fails.

However, battery-operated detectors remain the best bet for most homes because they can be placed in strategic spots without the need to run wiring. Use of long-lasting alkaline batteries can keep detectors reliable, but both battery and alarm should be tested periodically.

Manufacturers regularly add new smoke detectors with special features. A recent addition to the First Alert line, for example, is a special detector for kitchens with a button to control nuisance alarms caused by normal cooking. Pushing the button temporarily increases the level of smoke needed to set off the alarm.

A smoke detector equipped with an escape light, which turns on if the alarm is activated, is another excellent feature. Q. My home has three skylights at the top of shafts in the ceilings. In cold weather the skylights get condensation, and moisture drips into the house. What can I do about this? - D. Thatcher.

A. I suspect these are single-glass skylights, which are much more subject to condensation than double-glass or insulated units. The condensation results, of course, when warm air carries moisture up into the shaft and contacts the cold skylight surface. A strategy that sometimes works is to seal the shaft openings with acrylic "storm windows" that help keep moist air from entering the shafts and contacting the cold skylights. Probably the ultimate solution is to replace the skylights with modern insulated units designed to resist condensation.

Q. I patched hairline cracks in my concrete driveway with regular concrete patcher, but it crumbled and came out after a year. Is there a flexible material that can be used? - D. Organ.

A. Acrylic concrete patcher with some flexibility is sold in caulking-gun cartridges at some home centers and hardware stores. Inject a bead of the patcher into cleaned cracks and smooth the surface with a putty knife. However, I've tried many concrete patchers and still haven't found one that will never crumble or loosen.