Double-Insulated Tools
According to 1926.404(f)(7)(iv)(C)(6), Tools likely to be used in wet and/or conductive locations need not be grounded if supplied through an isolating transformer with an ungrounded secondary of not over 50 volts.
Listed or labeled portable tools and appliances protected by a system of double insulation, or its equivalent, need not be grounded. If such a system is employed, the equipment must be distinctively marked to indicate that the tool or appliance uses a system of double insulation. Double-insulated tools are often used in areas where there is considerable moisture or wetness. Look for the double-square (square within a square) symbol on the tool's label along the words "Double Insulated". It's the international Class II symbol (IEC 60417-5172).
Double-Insulated Tool
Although the user is insulated from the electrical wiring components, water can still enter the tool's housing. Ordinary water is a conductor of electricity. If water contacts the energized parts inside the housing, it provides a path to the outside, bypassing the double insulation. When a person holding a hand tool under these conditions contacts another conductive surface, an electric shock occurs.
If a power tool, even when double-insulated, is dropped into water, the employee should resist the initial human response to grab for the equipment without first disconnecting the power source.
Knowledge Check Choose the best answer for the question.
4-2. When a double-insulated power tool is dropped into water what should the employee do?
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