Outside Branch Circuits and Feeders practice questions

Correct: C — Six

225.33(A) limits the disconnecting means for each supply to not more than six switches or circuit breakers, whether mounted in a single enclosure, a group of separate enclosures, or a switchboard. Four and two are within the allowed range but not the maximum, and eight exceeds the limit set by this section.

Correct: A — 2.6 m (8 ft 6 in.)

225.19(A) sets the default clearance above a roof at 2.6 m (8 ft 6 in.), maintained 3 ft in all directions from the roof edge. The 900 mm figure only applies to roofs with a 4-in-12 slope or greater at 300V or less, and the 450 mm figure only applies to a qualifying short overhang run — neither condition is met here.

Correct: A — All ungrounded conductors

225.31(A) requires means to disconnect all ungrounded conductors that supply or pass through the building or structure. The grounded conductor isn't the target of this disconnecting requirement, and there's no ampere threshold or limitation to terminating conductors only.

Correct: D — 100 amperes, 3-wire

225.39(C) sets a dedicated minimum of 100 amperes, 3-wire for one-family dwelling feeder disconnects. The 60-ampere minimum applies to installations that don't fit any of the other named categories under 225.39(D), and the 15- and 30-ampere minimums apply to single- and two-circuit installations, not dwelling feeders.

Correct: C — In a readily accessible outdoor location on or within sight of the dwelling unit

225.41(A)(1) requires the disconnect to be in a readily accessible outdoor location on or within sight of the dwelling unit. An indoor location doesn't meet the outdoor requirement, and there's no 50 ft or utility-only-access provision in this section.

Correct: D — A surge-protective device installed in or adjacent to that distribution equipment

225.42(A) specifically requires an SPD where a feeder supplies guest rooms and guest suites of hotels and motels, among other sleeping occupancies — this is a feeder-level requirement, not limited to services or separate structures. The location is set by 225.42(B): in or adjacent to the load-side distribution equipment.

Correct: B — A permanent plaque or directory identifying all other services, feeders, or branch circuits and the area each serves

225.37 requires a permanent plaque or directory at each feeder and branch-circuit disconnect location, not just the main one, and it must denote all other supplies and the area each serves. Ordinary circuit labeling doesn't satisfy this, and the requirement doesn't hinge on whether utilities differ.

Correct: C — If the second feeder is only for a legally required standby system

225.30(A)(3) permits an additional feeder or branch circuit specifically for legally required standby systems. Distance from the dwelling, owner preference, and an undersized first feeder are not among the 225.30(A) through (F) exceptions — the fix for an undersized feeder is resizing it, not adding a second one.

Correct: B — 12 ft

Per 225.18(2), residential property and driveways at or below 300 volts to ground require only 12 ft of clearance. 10 ft applies only to pedestrian-only areas at or below 150 volts. 15 ft would apply to this same residential setting only if the voltage exceeded 300 volts to ground. 18 ft is for streets and truck traffic, not residential driveways.

Correct: A — 225.16(A)

225.16(A) governs the point of attachment itself, referring the installer to 230.26. 225.16(B) instead covers the means/fitting used to attach, and 225.15 addresses supports over buildings — not where the attachment point goes.

Correct: A — 3.0 m (10 ft)

225.4 sets the proximity trigger at 3.0 m (10 ft) from any building or structure other than supporting poles or towers. The 1.5 m, 3.7 m, and 4.5 m distances are clearances used elsewhere in the Code (such as vertical or over-roof clearances), not the insulation trigger in 225.4.

Correct: D — 8 AWG copper conductors with no messenger wire

225.6(A) requires at least 8 AWG copper (or 6 AWG aluminum) for spans longer than 15 m (50 ft) unless a messenger wire is used. The 10 AWG copper and 10 AWG aluminum options are only valid for spans up to 50 ft, and 12 AWG doesn't meet the minimum size for overhead spans at all, messenger or not — that size threshold applies to festoon lighting under 225.6(B), not general overhead spans.

Correct: D — 225.38(A)

225.38(A) requires that a power-operable disconnect be openable by hand in the event of a power failure. 225.38(B) governs simultaneous pole opening (a different concern), and 225.36 addresses the type of disconnecting means, not manual operability during a power outage.

Correct: A — 900 mm (3 ft)

225.19(D)(1) requires final spans to be kept not less than 900 mm (3 ft) from windows designed to be opened. Being a final span allows attachment to the building, but does not remove this clearance requirement, so the last option is wrong. The other distances are not the code value.

Correct: D — No, supports must be knobs, racks, brackets, or strain insulators made of glass, porcelain, or other approved material

225.12 requires open-conductor supports to be knobs, racks, brackets, or strain insulators made of glass, porcelain, or other approved material — a bare metal bracket with no insulating value doesn't meet that. Conductor separation is a separate requirement under 225.14(A) and doesn't substitute for proper supports, and open conductors aren't required to be in conduit under this section.

Correct: D — Stranded conductors only

225.24 requires that lampholders with insulation-piercing terminals be attached only to stranded conductors. Solid conductors, staggering aside, are not a substitute for this requirement — staggering addresses spacing of connections, not conductor type.