Give the best answer:

1. Which of the following overhead feeder conductors run outdoors must be insulated or covered?

a. On pole crossarms crossing a field

b. Along the edge of an alley near a building with a 5-ft setback

c. A final span arriving at a building

d. Two of the above

e. All of the above


2. Suppose you’re supplying a detached garage using an overhead drop (with individual conductors cabled together) originating on the side of the main building. Due to some intervening trees, you’d have to route the drop over or near a balcony on the garage side of the building. The pitched roof edge runs parallel to the balcony just above a 6-ft 8-in. sliding door to the balcony. Which of the following locations could serve as the point of attachment?

a. Just below the roof edge, over the balcony

b. Ditto, just to the outside of the balcony rail

c. Just to the left of a nearby second floor double-hung window

d. None of the above

e. More than one of the above


3. Which of the following would automatically justify an additional source of supply to a second building when the principal source was a 208Y/120V feeder?

a. 480V power circuit

b. A second occupancy

c. A three-way 120V switch loop

d. Two of the above

e. All of the above


4. Which of the following feeders, running as specified and supplying only a third building, needs a disconnecting means upon arrival at a second building between the first and the third?

a. Runs above a suspended ceiling

b. Runs in conduit on walls

c. Runs within 2-in. concrete encasement

d. Two of the above

e. All of the above

f. None of the above


5. If a campus-style educational facility maintains and documents (as acceptable to the AHJ) its switching procedures, which of these accommodations may it make in designing the sources and disconnecting means?

a. Use remote disconnecting means

b. Use multiple supply feeders with identical characteristics

c. Both of the above

d. None of the above


6. Which of the following buildings or structures need not have a local disconnecting means?

a. A car wash sign on a 14-ft support

b. Parking lot lighting standards

c. A unitized building with an integrated electrical system requiring an orderly shutdown protocol

d. Two of the above

e. All of the above


Answers and Discussion

1. d, Sec. 225-4. An overhead run near a building requires insulated (or covered) conductors if closer than 10 ft. You must observe this limit whether the conductors run parallel (response “b”) or terminate on the building (response “c”). However, a change in the 1999 NEC exempts “supporting poles or towers.”

2. d, Sec. 225-19(d). The 1999 NEC now correlates this subsection with Sec. 225-18. In this case, that prohibits either run above the balcony unless you provided a mast that lifted the point of attachment so the drop exceeded 10 ft over the balcony, or you landed the feeder at least 3 ft from the balcony rail. You can open double-hung windows, and observe a similar rule with respect to horizontal spacing.

3. d, Sec. 225-30(d). Response “b” requires special permission. The other responses work by right. You can apply response “c” even (for different uses) if it duplicates all other circuit characteristics.

4. d, Sec. 225-31; Sec. 225-32. The basic principle requires you to allow for local disconnection even if the feeder doesn’t supply anything within the second building. However, for the first time you can apply the separation allowances in Sec. 230-6 to these conductors. The panel reasoned that if encasement worked for unprotected service conductors, it would surely work for protected feeder conductors.

5. c, Sec. 225-30(e); Sec. 225-32 Ex. 1. Although this type of allowance used to only apply to industrial occupancies, now it’s broadened to any occupancy with safe switching procedures, on the literal text—even a detached garage. It also applies, for the first time, to multiple sources of supply. Although this concept ultimately means whatever the AHJ thinks it means, presumably it should only be applied where you have a documentable chain of command and responsibility.

6. e, Sec. 225-32, Ex. 2-4. You can use remote disconnecting means for buildings qualifying under Art. 685, as well as lighting and sign poles. In the case of the sign, be sure to consider the provisions of Sec. 600-6(a), which may effectively supersede these rules. That section requires an insight disconnect, although it need not be readily accessible. Even there, however, if you supply the sign through a contactor, you can substitute a lock-open disconnect within sight of the control mechanism.