NEC Commercial Electrical Practice Test

What type of receptacles are required for 15 and 20-ampere branch circuits?

1. Non-grounding type

2. GFI type

3. Grounding type

4. Isolated type

The correct answer is: Grounding type

For 15 and 20-ampere branch circuits, grounding-type receptacles are required. These receptacles are designed to provide a path for fault current, which improves safety by helping to prevent electrical shock hazards. In modern electrical installations, grounding is vital for user safety; therefore, the National Electrical Code (NEC) mandates that receptacles on these circuits must have a grounding provision. While non-grounding type receptacles may have been used in older installations, they are no longer considered safe for general use in most residential and commercial settings, especially in locations where grounding is advisable for the protection against electrical faults. Ground-fault circuit interrupter (GFCI) type receptacles offer additional protection against ground faults but are not a substitute for grounding in all instances. Isolated type receptacles are specialized and used in specific applications where isolation from the ground is necessary, but they do not fulfill the general requirements for typical branch circuits. Therefore, the grounding type receptacles are essential for ensuring compliance with the NEC and for maximizing both safety and functionality in electrical systems.