Double insulated refers to an electrical power tool that is constructed so the case is isolated from electrical energy and made of nonconductive material.

Double insulated refers to an electrical power tool that is constructed so the case is isolated from electrical energy and made of nonconductive material.

• A. Grounded
• B. Insulated
• C. Bonded
• D. Double insulated

Answer: (D)

Double insulation is a safety design that uses two independent barriers between live electrical parts and the user. In this setup, the outer case is nonconductive and acts as a second protective layer, so the user is protected even if one layer of insulation were to fail. Because the tool relies on this nonconductive housing rather than a grounding path, there’s no grounding conductor required for protection. So the statement describes the intended design: the case is isolated from electrical energy and made of nonconductive material, which is exactly what double insulation provides. Grounded tools rely on a ground path to carry fault current, and bonded refers to joining metal parts to maintain the same electrical potential; insulated alone doesn’t specify the two-barrier design that double insulation entails.

Double insulation is a safety design that uses two independent barriers between live electrical parts and the user. In this setup, the outer case is nonconductive and acts as a second protective layer, so the user is protected even if one layer of insulation were to fail. Because the tool relies on this nonconductive housing rather than a grounding path, there’s no grounding conductor required for protection.

So the statement describes the intended design: the case is isolated from electrical energy and made of nonconductive material, which is exactly what double insulation provides.

Grounded tools rely on a ground path to carry fault current, and bonded refers to joining metal parts to maintain the same electrical potential; insulated alone doesn’t specify the two-barrier design that double insulation entails.