Over 1000-Volt Branch Circuits and Feeders practice questions

Correct: C — A double-throw switch with more than one 'on' position

235.352(E) exempts switching devices with more than one 'on' position, such as a double-throw switch, from the up-is-on requirement. Ordinary single-throw switches — regardless of ampere rating or outdoor mounting — must still follow the rule.

Correct: D — A branch circuit tapped from the load side of the AC unit's disconnecting means

235.63(A) specifically prohibits connecting the required receptacle to the load side of the equipment's branch-circuit disconnecting means, since that would de-energize the receptacle exactly when a technician has shut the unit down to work on it. Feeding it from any other circuit, dedicated or general-purpose, is acceptable.

Correct: D — 16 A, which is 80% of the circuit rating

Per 235.23(A)(1), a cord-and-plug-connected utilization equipment not fastened in place cannot exceed 80% of the branch-circuit rating — 16 A on a 20 A circuit. The 50% figure is the cap for fastened-in-place equipment under 235.23(A)(2), not cord-and-plug loads, so it's a common mix-up but doesn't apply here.

Correct: A — The premises having branch circuits from more than one nominal voltage system

235.5(C)(1) applies specifically when the premises wiring has branch circuits supplied from more than one nominal voltage system — that condition, not circuit length, panelboard count, or ampacity, is what triggers the phase/voltage identification requirement.

Correct: A — Identification by phase or line and system at all termination, connection, and splice points

235.212(C)(1) requires each ungrounded conductor of a feeder to be identified by phase/line and system at every termination, connection, and splice point, not just at one location. The red/black polarity scheme belongs to DC systems under 235.212(C)(2), not multi-voltage AC feeders, and separate panelboards don't remove the marking requirement.

Correct: C — Not less than the noncontinuous load plus 125% of the continuous load

Per 235.20(A), the general rule applies the 125% factor only to the continuous load, then adds the noncontinuous load at 100%. Applying 125% to the whole combined load, or applying it to the noncontinuous portion instead, misreads which load gets the extra margin. The no-factor option is only valid under the 100%-listed-assembly exception, not the general rule.

Correct: B — By tested actual operation, such as current injection, confirming each circuit functions correctly

235.356(A) requires each circuit to be adjusted per the design and tested by actual operation, using current injection or an equivalent method, to the AHJ's satisfaction. Paper certificates, visual checks, and software modeling don't substitute for demonstrating real operation.

Correct: C — 125% of the designed potential load of equipment operated simultaneously

235.19(A) sets a single flat multiplier: 125% of the designed potential load of simultaneously operated equipment. The continuous-plus-noncontinuous split is the familiar formula for circuits under 1000 volts, not this article, and pure engineering judgment is only permitted under the supervised-installation path in 235.19(B).

Correct: B — 235.339

235.339 requires the feeder or branch-circuit disconnecting means to be rated not less than the calculated load per Article 220. 235.352 covers disconnecting means requirements like location and type, not rating; 235.351 covers isolating switches; 235.360 covers roadway/walkway clearances — none address minimum disconnect rating.

Correct: D — 235.202(A)

235.202(A) governs feeders supplying only transformers, requiring ampacity not less than the sum of the transformer nameplate ratings. 235.202(B) is the closest distractor but only applies when the feeder also serves utilization equipment directly, and 235.203 covers overcurrent protection, not conductor sizing.

Correct: B — When the feeder supplies branch circuits that require equipment grounding conductors

235.206 conditions the feeder EGC requirement on whether the branch circuits it supplies require equipment grounding conductors — there's no ampere-rating threshold, physical-damage trigger, or motor-load-only trigger in this section.

Correct: B — Six times the conductor ampacity

235.408 permits a circuit breaker trip setting of not more than six times the conductor ampacity for high-voltage service protection. Three times ampacity is the limit that applies to fuses, not breakers, and 125%/80% are low-voltage continuous-load figures that don't govern here.

Correct: C — A pole in each ungrounded conductor of the tapped circuit

235.10 requires switching devices in the tapped circuit to have a pole in each ungrounded conductor. Switching only one ungrounded conductor, switching the grounded neutral, or assuming a length exception all misstate the rule — 235.10 has no length-based exception for switching.

Correct: B — 235.11

235.11 is the general rule that the number of branch circuits must be sufficient to supply the total calculated load. 235.19(A) instead sets minimum conductor ampacity/size once circuits are chosen, and 235.20(A) sets overcurrent device sizing for continuous/noncontinuous loads — neither addresses how many circuits are needed.

Correct: D — 235.361(A)

235.361(A) hosts Table 235.361(A), which gives clearances over buildings and other structures for conductors 22 kV or less to ground. 235.360(A) looks similar but governs clearances over roadways, walkways, rail, water, and open land, not over buildings.

Correct: D — Take the Table 235.360(A) value and add 10 mm (0.4 in.) per kV above 22 kV

Per 235.360(B), clearances from Table 235.360(A) get increased by 10 mm (0.4 in.) per kV, or major fraction thereof, only for the amount more than 22 kV — here that's 12 kV worth of adder, not the full 34 kV. Table 235.360(A) alone only covers up to 22 kV, and this is a routine voltage case, not the unusual-crossing special case in 235.360(C).

Correct: D — 235.212(B)

235.212(B) points to the identification rules for the equipment grounding conductor of a feeder (per 250.119). 235.206 covers sizing of the feeder EGC, not its identification, 235.212(A) governs the grounded (neutral) conductor, and 235.212(C) governs ungrounded conductors — neither addresses EGC marking.

Correct: D — Only if the authority having jurisdiction requires it

235.205 makes the diagram requirement conditional entirely on the AHJ asking for one — there's no size, occupancy, or multi-building trigger written into the section itself.

Correct: C — 235.203

235.203 is the standalone rule stating that feeders shall be protected against overcurrent. 235.202 (and its subsection 235.202(C)) covers minimum rating and size of feeder conductors, not the overcurrent protection requirement itself.