Which statement correctly distinguishes Class I from Class II electrical equipment?

• A. Class I requires protective earth and Class II uses double or reinforced insulation.
• B. Class I uses double insulation.
• C. Class II requires earth connection.
• D. Class II has exposed metal parts bonded to earth.

Answer: (A)

Class I equipment safety relies on a protective earth connection for fault protection. The exposed metal parts are bonded to earth so, if a live conductor touches the chassis, fault current flows safely to ground and a protective device trips. Class II equipment, on the other hand, uses double insulation or reinforced insulation to isolate live parts from users, so it does not rely on an earth grounding path and typically has no exposed conductive parts that require grounding. Therefore, the statement that correctly distinguishes them is that Class I requires protective earth and Class II uses double insulation. The other statements mix up these concepts: Class I is not defined by double insulation, Class II does not require an earth connection, and Class II devices generally do not have exposed metal parts bonded to earth.