Abstract: In the process of drilling a concrete in a building, many times contact and damage can accidentally be made with existing electrical conduit and the wires inside, or plumbing pipes. This damage can be avoided with a device which can indicate a grounded metal, such as a conduit, plumbing pipes, supporting frames or metal beam, all of which may be grounded to the existing electrical system. A safety protection circuit is incorporated into a power tool and includes at least one LED indicator connected to a low voltage power supply and to the body of the power tool to be illuminated when contact with grounded metal occurs.

Abstract: In the process of drilling a concrete in a buildings many times accidentally can be damage existing electrical conduit and the wires inside or plumbing pipes. All these damages can be avoided with a device which can indicate a grounded metal. Grounded metal is any metal object which is grounded to the existing electrical system in the building, such a conduit, plumbing pipes, supporting frames or metal beam.