Wiring and Protection Flashcards

A service has 3/0 AWG copper ungrounded service-entrance conductors. Per NEC Table 250.66, what is the minimum copper grounding electrode conductor size?

Answer: 4 AWG

Table 250.66 requires 4 AWG copper for 2/0 or 3/0 copper service conductors.

Per NEC 250.53(A)(2), when a single rod, pipe, or plate electrode does not have a resistance to earth of 25 ohms or less, what must be done?

Answer: Supplement it with an additional electrode

The single electrode must be supplemented by an additional electrode, unless it measures 25 ohms or less.

When multiple rod electrodes are installed to meet NEC 250.53, what is the minimum spacing between them?

Answer: 6 ft

NEC 250.53(B) requires at least 6 ft between rod, pipe, or plate electrodes.

Per NEC 250.66(A), when a grounding electrode conductor is the sole connection to a rod, pipe, or plate electrode, it need not be larger than which copper size?

Answer: 6 AWG

For the portion connecting only to rod, pipe, or plate electrodes, 6 AWG copper is the maximum required size.

Per NEC 230.24(B), what is the minimum clearance for service-drop conductors (300 V to ground or less) over a residential driveway not subject to truck traffic?

Answer: 12 ft

NEC 230.24(B)(2) requires 12 ft over residential property and driveways for voltages not exceeding 300 V to ground.

Under NEC 230.67 (2020/2023), what surge protection is required for services supplying dwelling units?

Answer: A Type 1 or Type 2 SPD that is an integral part of, or located immediately adjacent to, the service equipment

NEC 230.67 requires a Type 1 or Type 2 SPD at or immediately adjacent to the dwelling service equipment.

Per NEC 210.52(E)(1), a one-family dwelling needs at least one outdoor receptacle accessible from grade at both the front and back, mounted not more than how high above grade?

Answer: 6½ ft

Outdoor receptacles at the front and back must be readily accessible from grade and not more than 6½ ft above grade.