WASHINGTON -- Robert Bosch Corp. of Mt. Prospect, IL, has voluntarily recalled approximately 20,000 hammer drills due to a potential electrical shock hazard.

While no incidents have been recorded, the U.S. Consumer Product Safety Commission said the units have a grounding system and trigger switch that could cause ground wire abrasion and/or ground connector failure posing a shock hazard. In addition, the switch trigger could become stuck in the "on" position posing an injury hazard to the user.

The recall involves Bosch 1/2 inch 2-Speed Hammer Drill with model number HD19-2, HD19-2D, HD19-2L and 1/2 inch 2-Speed Hammer Drills with model number HD 21-2. The units were sold at home improvement, hardware and major retailers nationwide and various distributors from September 2009 through August 2010 for between about $140 and $220. The products were made in Switzerland.

Consumers are urged to return recalled the hammer drill to Robert Bosch Tool for repair.