Critical Operations Power Systems practice questions

Correct: B — A minimum 15-minute setting to avoid retransfer on short-time reestablishment of the source

708.20(F)(1) requires a time-delay feature permitting a minimum 15-minute setting before retransfer, so a brief blip in the normal source doesn't cause nuisance transfers back and forth. There's no provision allowing zero delay, a 5-minute cap, or the shorter emergency-system-style delay used elsewhere in the Code.

Correct: D — Reevaluate selective coordination with all supply-side and load-side OCPDs

708.54(B) requires that when critical operations power system OCPDs are replaced, they be reevaluated to ensure selective coordination is maintained with ALL supply-side and load-side OCPDs, not just the ampere rating or the nearest device.

Correct: B — Fully selective, 100 percent

708.52(D) requires ground-fault protection for the service and feeder disconnecting means to be fully selective, achieving 100 percent selectivity so the feeder device opens without the service device opening. There is no 80 percent threshold here (that rule applies elsewhere, to branch-circuit loading, not GFP selectivity), and the section does not carve out an exception for short-circuit-only coordination or same-manufacturer breakers.

Correct: B — 708.54(A)

708.54(A) is the General provision requiring COPS OCPDs to be selectively coordinated with supply-side and load-side devices, with documentation available to authorized personnel. 708.52(D) (Selectivity) instead addresses ground-fault protection selectivity, not overcurrent selective coordination generally, and 708.24(F) covers transfer equipment documentation, not OCPD coordination.

Correct: B — 708.10(D)

708.10(D) governs COPS branch circuit wiring and its subpart on 'Within the DCOA' permits any Chapter 3 wiring method for that portion of the run. 708.10(C) is titled 'COPS Feeder Wiring Requirements' — it covers feeders, not branch circuits, so it doesn't apply to this branch-circuit scenario.

Correct: D — The system must be evaluated for cybersecurity or have a cybersecurity assessment conducted

708.7 requires a networked COPS control interface to either be identified as evaluated for cybersecurity or have a cybersecurity assessment conducted for vulnerabilities. Encryption specifics, dedicated circuits, and UL 508A panel listing are not the compliance mechanism this section establishes.

Correct: C — 708.11(B)

708.11(B) covers feeder distribution equipment itself (transfer equipment, transformers, panelboards) and requires 2-hour fire-rated spaces above the 100-year floodplain. 708.10(C)(2) and 708.10(C)(3) address protection of the feeder wiring/conductors, not the location of the distribution equipment.

Correct: B — 72 hours

708.22(C) requires the alternate source to operate the COPS at full load of the designated critical operations area for a minimum of 72 hours. The 24-hour and 48-hour options are shorter durations sometimes confused with other standby or emergency system rules, and 96 hours overstates the actual code minimum.

Correct: A — Rigid metal conduit

708.10(C)(1) permits rigid metal conduit, intermediate metal conduit, and Type MI cable as stand-alone physical protection. EMT, Schedule 40 PVC, and flexible nonmetallic raceways are only permitted when encased in not less than 2 in. of concrete.

Correct: C — COPS and emergency circuits

708.22(B) sets a strict priority: COPS and emergency circuits first, legally required standby circuits second, and optional standby circuits last. The legally required standby and optional standby circuits are lower priority, not first.

Correct: B — 708.10(A)(1)

708.10(A)(1) specifically requires boxes and enclosures for COPS circuits — including transfer switches, generators, and power panels — to be permanently marked when other power systems are also present in the building. 708.11(A) instead addresses branch circuit distribution equipment location/access, not marking, and 708.5 covers physical security, not identification.

Correct: A — The results of a risk assessment

708.5(A) requires the security strategy to be developed, documented, and implemented based on the results of a risk assessment. Specific hardware like alarms or fencing isn't mandated by this section, and the assessment must happen up front, not reactively after an incident.

Correct: A — It must be documented and conducted per the process in 708.4(A) through (C)

708.4 requires the risk assessment to be documented and conducted in accordance with 708.4(A) through (C). The Code does not mandate AHJ pre-approval of the assessment itself, does not restrict who performs it to a structural engineer, and does not limit assessment timing to after an outage — those are plausible-sounding but unsupported requirements.

Correct: C — Part of a listed 2-hour fire-resistive cable system or protected by a listed 2-hour electrical circuit protective system

708.14(7) requires these cables to be riser-rated AND part of a listed 2-hour fire-resistive cable system or protected by a listed 2-hour electrical circuit protective system. Riser-rating alone is not sufficient, and 1-hour or plenum-only ratings do not meet the 2-hour requirement in 708.14.

Correct: B — 708.6(E)

708.6(E) specifically requires means for testing critical power systems under maximum anticipated load conditions. 708.8(D) covers functional performance tests during initial commissioning, not the recurring means for full-load testing, and 708.6(A)/708.6(C) address AHJ witnessing and preventive maintenance programs rather than load testing capability.

Correct: C — An additional step of ground-fault protection at the next feeder disconnecting means downstream toward the load

708.52(B) requires that once GFP is provided per 230.95 or 215.10, an additional step of ground-fault protection be added at the next level feeder disconnecting means downstream toward the load — the upstream protection isn't relocated or considered sufficient alone.

Correct: D — 708.24(C)

708.24(C) governs automatic transfer switches used with non-synchronized sources, requiring them to be listed for emergency use and to be electrically operated, mechanically held. 708.24(B) instead covers bypass isolation switches, a different transfer switch configuration, and 708.24(D) covers redundant transfer equipment, not the basic listing/operation requirement.

Correct: C — An automatic battery charging means shall be provided

708.20(E) requires an automatic battery charging means — manual-only charging or ad hoc inspection schedules don't satisfy this. It also explicitly bars automotive-type batteries, so the deep-cycle automotive option is wrong regardless of duty rating.