If a power tool is not provided with a three-wire grounded cord, what safety design feature can be used as an alternative?

If a power tool is not provided with a three-wire grounded cord, what safety design feature can be used as an alternative?

• A. Double Insulation
• B. Ground Fault Circuit Interrupter
• C. Shielded Cable
• D. Battery Power Only

Answer: (A)

When a power tool isn’t provided with a three-wire grounded cord, using double insulation as a safety design feature keeps the user protected by isolating live parts from the outside. Double insulation means there are two layers of insulation (or reinforced insulation) and/or a sturdy outer shell, so even if the inner insulation were damaged, a live part is unlikely to contact the user. This is why such tools are built as Class II equipment, and you’ll often see the square-in-square symbol on the tool indicating this design. A ground fault circuit interrupter can add protection by quickly cutting power if a fault current leaks to ground, but it’s a circuit-level protection device, not a design feature built into the tool itself. Shielded cable helps reduce interference or risk in some applications but doesn’t ensure user protection if a fault energizes the tool’s surface. Battery power avoids the grounding issue by not using a cord at all, but it’s a power source change rather than a protective design feature of the tool’s construction.

When a power tool isn’t provided with a three-wire grounded cord, using double insulation as a safety design feature keeps the user protected by isolating live parts from the outside. Double insulation means there are two layers of insulation (or reinforced insulation) and/or a sturdy outer shell, so even if the inner insulation were damaged, a live part is unlikely to contact the user. This is why such tools are built as Class II equipment, and you’ll often see the square-in-square symbol on the tool indicating this design.

A ground fault circuit interrupter can add protection by quickly cutting power if a fault current leaks to ground, but it’s a circuit-level protection device, not a design feature built into the tool itself. Shielded cable helps reduce interference or risk in some applications but doesn’t ensure user protection if a fault energizes the tool’s surface. Battery power avoids the grounding issue by not using a cord at all, but it’s a power source change rather than a protective design feature of the tool’s construction.