Marinas and Docking Facilities practice questions

Correct: A — 6.0 m (20 ft)

555.34(B)(1) requires overhead wiring to avoid being closer than 6.0 m (20 ft) from the outer edge of any area used for moving vessels or stepping/unstepping masts. The 5.49 m (18 ft) figure is the minimum height above grade for wiring elsewhere in the yard under 555.34(B)(2), a different requirement, and 2.5 m (8 ft) is the conduit protection height under 555.34(B)(4).

Correct: D — Locking and grounding type

Per 555.33(A)(4)(a), receptacles rated 30 amperes and 50 amperes must be of the locking and grounding type. Pin and sleeve type is required only for receptacles rated 60 amperes or higher, per 555.33(A)(4)(b).

Correct: B — Connect it to the grounding bus in the panelboard with a solid copper conductor not smaller than 8 AWG

555.13 requires non-current-carrying metal parts likely to become energized, and not already connected to an equipment grounding conductor, to be bonded to the panelboard grounding bus with solid copper conductor sized 8 AWG or larger. Aluminum conductors don't satisfy the solid copper requirement, and the rule doesn't limit bonding to only metal touching the water — it also covers piping and other metal parts likely to become energized.

Correct: D — Wire-type, insulated, sized per 250.122 but not smaller than 12 AWG

555.37(B) requires a wire-type, insulated EGC sized per 250.122 but never smaller than 12 AWG. Using the raceway as the EGC or leaving it bare are both real practices allowed elsewhere in the NEC, but not here — marinas specifically require insulated wire-type conductors.

Correct: C — At least 305 mm (12 in.) above the deck, and not below the electrical datum plane

555.30(A) requires connections not intended for submerged operation to be at least 305 mm (12 in.) above the deck AND not below the electrical datum plane — both conditions apply together, not just the height alone. The 24 in. figure and 'anywhere above the waterline' options misstate the rule.

Correct: A — A listed, wet-location-rated emergency shutoff device marked 'Emergency Shutoff,' located within sight of the outlet

555.36(C) requires a listed emergency shutoff device or disconnect, marked 'Emergency Shutoff,' that is within sight of the outlet, readily accessible, externally operable, manually resettable, and wet-location listed. A circuit breaker handle is explicitly disallowed, a device out of sight of the outlet fails the within-sight requirement, and a GFCI reset button is not a disconnecting means for this purpose.

Correct: B — Yes, because it is within 10 ft of the body of water

Per 555.14(A), an equipotential plane is required if EITHER condition is met: voltage exceeds 250 V to ground, OR the equipment is within 3 m (10 ft) of the water. Being within 10 ft alone is sufficient — the voltage threshold doesn't also have to be met, so the 'only if both' and 'voltage too low' options are wrong.

Correct: B — So motion from water surface changes and water level changes doesn't create an unsafe condition

555.52(A) requires flexibility specifically so motion of the water surface and changes in water level don't stress the wiring into an unsafe condition. It has no bearing on conductor sizing, service-versus-feeder classification, or grounding electrode requirements, which are addressed elsewhere.

Correct: B — Listed GFPE rated not more than 30 milliamperes

555.35(B)(1) specifically requires listed GFPE rated not more than 30 mA for shore-power receptacles — a tighter, differently-named requirement than the general GFCI protection used for other marina outlets under 555.35(B)(2).

Correct: A — A listed leakage current measurement device to test each boat

Per 555.35(D), where more than three receptacles supply shore power to boats, a listed leakage current measurement device must be available and used to determine leakage current from each boat. GFPE protection and grounding conductor requirements are addressed elsewhere in Article 555, not by this section, and cord amperage logging isn't a requirement here.

Correct: A — The current edition of the NEC, with the circuit requiring inspection

555.15 requires that modifications or replacements of enclosures, devices, or wiring methods at a docking facility comply with the current Code, and that the circuit be inspected. The original 2014 edition only governs repair of damaged equipment that is being fixed rather than replaced, not new replacement work.

Correct: A — WARNING — POTENTIAL SHOCK HAZARD — ELECTRICAL CURRENTS MAY BE PRESENT IN THE WATER.

555.10(3) requires the exact wording "WARNING — POTENTIAL SHOCK HAZARD — ELECTRICAL CURRENTS MAY BE PRESENT IN THE WATER." The other options sound like reasonable hazard signage but none match the code-mandated text.

Correct: A — 555.32

555.32 covers gasketed enclosures for breakers, switches, panelboards, and marina power outlets, and specifically requires a weep hole to discharge condensation. 555.31(B) only addresses equipment location, not condensation drainage.

Correct: D — 555.37(E)

555.37(E) directly governs grounding of cord-and-plug-connected appliances, requiring an equipment grounding conductor in the cord plus a grounding-type attachment plug unless the appliance is double-insulated. 555.37(A) only lists what equipment must be connected to the EGC, and 555.37(B) covers the type of EGC used generally, not the cord-and-plug appliance grounding path itself.

Correct: C — 555.3(C)

555.3(C) sets the datum plane 2 ft above the highest normal water level for land areas not subject to tidal fluctuation. 555.3(B) applies only where tidal fluctuation occurs, 555.3(A) governs floating piers instead of fixed land-based sites, and 555.14(A) covers equipotential planes, not the datum plane elevation.

Correct: C — 555.37(C)

555.37(C) is the specific rule requiring an insulated equipment grounding conductor from the service grounding terminal to the remote panelboard's grounding terminal/busbar on a feeder. 555.37(D) covers only branch-circuit EGC termination, not the feeder run, and 555.35(A) addresses feeder ground-fault protection, not the equipment grounding conductor path.

Correct: D — Securely and substantially supported by structural members, independent of any connected conduit

555.31(A) requires the enclosure to be securely and substantially supported by structural members independent of any conduit connected to it — the conduit cannot serve as the support. External ears/lugs are only relevant to the water-sealing requirement, not as a stand-alone support method, and relying on conduit or screws alone does not meet the rule.

Correct: C — 555.54(B)

555.54(B) specifically addresses installation and connection of the equipment grounding conductor for grounding electrode work at services/feeders — it must run with the feeder conductors and land on a grounding terminal in the service equipment. 555.54(A) covers grounding of electrical/nonelectrical parts generally, and 555.37(C) governs the separate feeder EGC sizing rule for the marina wiring system, not routing at the service.

Correct: C — The grounding bus

555.56(A) requires all enclosures and exposed metal parts of electrical systems to connect to the grounding bus. A separate ground rod at each enclosure isn't the rule here, tying to the neutral bus conflates grounding with neutral bonding (which is not permitted this way), and a watertight marking doesn't exempt equipment from grounding requirements.

Correct: D — At the service equipment only

555.55 requires the neutral to connect to the equipment grounding terminal only at the service equipment; every other panelboard, enclosure, and appliance terminal must keep the neutral insulated. Bonding at additional panelboards or appliance terminal blocks is the kind of multi-point bonding this section specifically prohibits.