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.