Luminaires and Lighting practice questions

Correct: D — 300 mm (12 in.)

Per 410.16(D)(1), surface-mounted incandescent or LED luminaires with a completely enclosed light source require 300 mm (12 in.) clearance. The 150 mm (6 in.) figure applies to surface-mounted fluorescent and to all recessed types, not this one.

Correct: C — A surface-mounted incandescent luminaire with a completely enclosed light source

410.16(B) permits surface-mounted or recessed incandescent or LED luminaires only when the light source is completely enclosed. Pendant luminaires, bare lampholders, and open or partially enclosed incandescent lamps are all expressly prohibited by 410.16(C).

Correct: C — 600 mm (24 in.)

410.16(A) sets the lower storage-space boundary at 600 mm (24 in.) from the side and back walls, from the floor up to 6 ft or the highest rod. The 300 mm (12 in.) distance and shelf-width option apply only to the upper zone between that height and the ceiling, not the lower zone.

Correct: A — It is identified as inherently protected or identified for and installed in poured concrete

Per 410.130(F)(2) and 410.130(F)(3), thermal protection may be omitted only if the luminaire is identified as inherently protected (equivalent performance to a thermally protected luminaire) or identified for and installed in poured concrete. Damp-location rating, clearance from insulation, and remote ballast location don't exempt a recessed HID luminaire from the thermal protection requirement.

Correct: B — Yes, because it is closer than the 38 mm (1½ in.) minimum spacing required for the small-isolated-parts exception

410.42(2) only exempts small isolated parts like decorative bands when they're spaced at least 38 mm (1½ in.) from lamp terminals. At 25 mm, the band fails that spacing requirement, so the general rule in 410.42 applies and it must connect to an equipment grounding conductor.

Correct: C — No, because the zone extends 8 ft vertically from the rim and is all-encompassing, including the space directly over the tub

410.10(D)(1) prohibits chain-, cable-, or cord-suspended luminaires anywhere within a zone 3 ft horizontal and 8 ft vertical from the tub rim, and states the zone is all-encompassing, including directly over the tub. The '3 ft horizontal only' and 'below 8 ft is fine' choices both misread the zone as one-dimensional rather than a full 3D exclusion volume. The fixture type isn't the deciding factor — cord-connected, chain-, cable-, and cord-suspended luminaires, track lighting, pendants, and paddle fans with light kits are all barred the same way. See 410.10(D).

Correct: B — 12 in.

410.116(A)(1) requires non-Type IC recessed luminaires to keep all recessed parts at least 12 in. from combustible materials. The 3 in. figure is the separate thermal-insulation clearance from 410.116(B), not the combustible-material clearance, and general UL listing doesn't override this specific spacing requirement.

Correct: B — 410.137(B)

410.137(B) states that separately mounted ballasts, transformers, LED drivers, or power supplies listed for direct connection to the wiring system are not required to be additionally enclosed. 410.137(A) instead covers auxiliary equipment (reactors, capacitors, resistors) that must be enclosed in metal cabinets, which is the opposite situation.

Correct: A — An insulating bushing sized appropriately for the cord

410.62(A) requires an insulating bushing at the inlet of a metal lampholder attached to flexible cord, with burrs removed for a smooth bearing surface. Strain relief, grounding bushings, and weatherproof gaskets are not the requirement stated in this section.

Correct: C — Six

410.59 caps groups of cord-coupled showcases at not more than six, with one of the group connected by flexible cord to a permanently installed receptacle. There is no ampacity-based workaround to exceed that count.

Correct: C — Only if the equipment is designed so no live parts are exposed while lamps are inserted, in place, or removed

410.135 permits equipment with open-circuit voltage exceeding 300 volts in dwellings only when designed so there are no exposed live parts during lamp insertion, service, or removal. Avoiding oil-filled transformers (410.130(C)) is a separate, unrelated requirement, a flat ban ignores the design exception, and the 1000-volt identification rule in 410.130(A) governs equipment listing, not dwelling permission.

Correct: A — Whenever the luminaire's ballast or LED driver can be serviced in place, in an indoor non-dwelling location

410.71(1) requires a disconnecting means for indoor, non-dwelling double-ended lamp luminaires whose ballast or LED driver can be serviced in place. Hazardous locations and emergency illumination under 700.16 are actually exceptions where a disconnect is NOT required, and the multiwire condition only governs how the disconnect must function, not whether one is needed.

Correct: C — The luminaire must be located directly below the outlet or busway

410.62(C)(1) requires the luminaire be located directly below the outlet or busway, with the cord visible over its entire length except at terminations and not subject to strain or damage. Concealing the cord contradicts the visibility requirement, mogul-base lampholders are a separate allowance under 410.62(C)(2), and the 50 A limit (not 20 A) applies only to that mogul-base provision.

Correct: B — A general-purpose ballast in an indoor fluorescent luminaire

410.130(E)(1) requires integral thermal protection for indoor fluorescent ballasts generally. The other three are explicit exceptions: simple reactance ballasts with straight tubular lamps under 410.130(E)(2), exit luminaires under 410.130(E)(3), and egress-only luminaires under 410.130(E)(4) are all exempted — the latter two are actually prohibited from having it.

Correct: D — No, the system must be listed and identified specifically as a germicidal system

410.197(A) requires the system be listed and identified as a germicidal system specifically, because that listing is what verifies the occupancy safeguard against UV exposure. A general UV luminaire listing doesn't satisfy this, and a warning sign doesn't substitute for listing. Germicidal systems are in fact listed products, not field-evaluated installations.

Correct: D — If the luminaire is listed and identified for use in dwellings

Per 410.195(C), germicidal luminaires cannot be installed in a dwelling unit unless they are listed and identified for use in dwellings. Mounting height and physical barriers, while relevant to other subsections, don't override the dwelling-specific listing requirement.

Correct: D — It is not permitted in or on dwelling occupancies

410.140(B) is an outright prohibition: equipment with open-circuit voltage exceeding 1000 volts shall not be installed in or on dwelling occupancies. Being listed, limiting to certain rooms, or adding GFCI protection doesn't create an exception — the section allows none.

Correct: D — It must be enclosed, identified for the use, and listed

410.143(A) requires the transformer to be enclosed, identified for the use, and listed — a field-built or open-frame unit doesn't meet this, and the listing/identification requirement applies universally, not just in dwellings.

Correct: A — 410.150(B)

410.150(B), Connected Load, is the specific rule stating the connected load must not exceed the track rating and that the branch circuit must not exceed the track rating, while exempting the installation from the 220.46(B) length/luminaire-count limitation. 410.150(A) only defines what lighting track is, and 410.150(C) addresses prohibited locations, not load calculations.

Correct: B — 12 AWG copper

410.155(A) requires track conductors to be a minimum of 12 AWG or equal and to be copper. 14 AWG copper is too small, and aluminum or copper-clad aluminum are not permitted regardless of size.

Correct: A — Two supports

410.154 requires a single section 4 ft or shorter to have two supports unless the track is identified for supports at greater intervals. One support is insufficient and three is more than the base rule requires for a standalone section.

Correct: B — At least 38 mm (1½ in.) of spacing between the driver and the fiberboard surface

410.136(B) requires either a listing/marking for mounting on low-density cellulose fiberboard or a minimum 38 mm (1½ in.) spacing from the fiberboard surface. A flame spread index under 25 would actually reclassify the material outside the 'low-density cellulose fiberboard' definition entirely, so it doesn't substitute for the spacing rule, and recessing/grounding requirements aren't what this subsection addresses.

Correct: D — 410.30(B)

410.30(B) is the section governing metal or nonmetallic poles supporting luminaires, including the handhole requirement (and its exceptions for short poles or hinged bases). 410.36(A) covers luminaires supported by outlet boxes, not pole handholes, and 410.24(B) addresses access to boxes for electric-discharge/LED luminaires, not pole handholes.

Correct: B — One 2-wire branch circuit, or one multiwire branch circuit, plus one additional 2-wire branch circuit

410.64(C) caps the assembly at a 2-wire branch circuit or a multiwire branch circuit supplying the connected luminaires, plus one additional 2-wire branch circuit separately supplying one or more of them. Unlimited 2-wire circuits or two multiwire circuits both exceed what the section allows.

Correct: C — The luminaire must be identified for use within commercial cooking hoods and meet all other listed conditions in 410.10(C)

410.10(C) permits luminaires in commercial cooking hoods only when all four listed conditions are satisfied together, starting with being identified for that specific use. Running wiring in flex inside the hood doesn't satisfy the rule, since 410.10(C)(4) prohibits exposed wiring methods within the hood at all. Corrosion resistance alone (one of four conditions) isn't sufficient by itself, and the installation isn't blanket-prohibited — it's conditionally permitted.

Correct: A — Suitable for wet locations

Per 410.10(A), luminaires installed in wet locations must be marked as suitable for wet locations. A damp-location marking alone does not meet the wet-location requirement, since damp locations accept either marking but wet locations require the wet-rated marking specifically.

Correct: C — 14 AWG

410.54(B) sets 14 AWG as the minimum for mogul-base or medium-base screw shell lampholders. 18 AWG is only permitted for intermediate or candelabra-base lampholders, so it would undersize a medium-base application.

Correct: D — 410.82

410.82 covers portable luminaires wired with flexible cord and requires the grounded conductor to be identified and attached to the screw shell and identified blade when an Edison-base lampholder is used. 410.90 (Screw Shell Type) addresses polarity of screw-shell lampholders generally, not the portable luminaire cord/plug wiring requirement, so it's a tempting but wrong match.

Correct: C — Only outside the arms and stems, and only if the splice is necessary

Per 410.56(C), splices and taps are not permitted within luminaire arms or stems. Per 410.56(D), even outside those locations, no unnecessary splices or taps are allowed within or on a luminaire — so a splice must be both outside the arm/stem and actually needed.

Correct: D — 410.122

410.122 requires incandescent luminaires to be permanently marked with maximum allowable lamp wattage in letters at least 6 mm high, visible during relamping. 410.126 instead covers lampholder requirements, not wattage marking, so it doesn't govern this labeling rule.

Correct: D — The environmental conditions, current, voltage, and temperature the conductor will be subjected to

410.52 requires insulation suitable for the full set of conditions — environmental exposure, current, voltage, and temperature — not any single factor alone. The overcurrent device rating, lamp wattage, and room ambient temperature are each only one piece of the actual operating conditions inside the luminaire.

Correct: A — It must simultaneously disconnect all the ungrounded conductors

410.104(B) requires the switching device to simultaneously disconnect all ungrounded conductors supplying the auxiliary equipment. Relying on the branch-circuit breaker or switching conductors separately does not satisfy this simultaneous-disconnect requirement.

Correct: C — 410.24(A)

410.24(A) governs the wiring methods (raceway, MC, AC, MI, NM cable, or flexible cord per 410.62(B)/(C)) used to connect a luminaire that is independently supported. 410.36(A) instead addresses luminaires that ARE supported by the outlet box, and 410.30(A) covers general support requirements, not the connection wiring method.

Correct: C — It must be a grounded system

410.138 requires that an autotransformer raising ballast voltage above 300 volts be supplied only by a grounded system. It does not require an isolation transformer or a GFCI, and a listed ballast doesn't waive the grounded-system requirement.

Correct: B — It must be listed and identified as germicidal equipment

410.191 specifically requires luminaires intended to emit germicidal irradiation to be listed and identified as germicidal equipment. A general-use listing, a wet-location listing, or field inspection alone does not satisfy this germicidal-specific requirement.

Correct: B — Connected to the equipment grounding conductor per Part V of Article 410

410.182 requires horticultural lighting equipment to connect to the equipment grounding conductor per Part V, the same as any other luminaire. Being identified for horticultural use doesn't exempt the fixture, the requirement isn't location-triggered, and there's no separate horticultural grounding electrode conductor.

Correct: D — Interconnecting horticultural lighting luminaires as part of listed equipment

410.178(2) permits flexible cord for interconnecting horticultural lighting luminaires, but only when the cord is provided as part of listed equipment identified for horticultural use. Wiring inside a wall cavity is fixed wiring, not a permitted cord use; the rule applies only to listed equipment, not any luminaire; and general-purpose receptacle extension isn't one of the three permitted uses.

Correct: D — A listed GFCI

410.184 requires a listed GFCI for any horticultural lighting equipment using flexible cords with separable connectors or attachment plugs. SPGFCI is only required above 150 volts to ground, which doesn't apply at 120 volts. AFCI and 'no protection' both ignore the mandatory GFCI requirement.

Correct: B — Listed

410.172 requires that lighting equipment identified for horticultural use shall be listed, with no carve-out for dwelling-only use, AHJ field evaluation in place of listing, or installer self-labeling.

Correct: D — Only if the manufacturer's instructions indicate such use

410.176(A) prohibits using horticultural lighting equipment for general illumination unless the manufacturer's instructions indicate that use. It's not an absolute ban, and there's no dwelling-unit or engineer-approval exception in this section.

Correct: C — A caution label stating the rated open-circuit voltage, in letters at least 6 mm high

Because the open-circuit voltage exceeds 1000 volts, 410.146 requires a legible "Caution ____ volts" marking showing the actual rated open-circuit voltage, in letters not less than 6 mm high. The requirement applies to secondary circuits specifically and is not limited to outdoor installations, and a generic "Danger" label without the voltage value does not satisfy the rule.

Correct: C — It is capable of being locked open in accordance with 110.25

Per 410.141(B), the switch or circuit breaker must be within sight of the luminaires or lamps, or it is permitted to be located elsewhere only if it is lockable open per 110.25. A warning tag or a distance rule does not satisfy this — locking open is the only substitute for sight visibility.

Correct: A — 410.142

410.142 specifically governs lamp terminals and lampholders, requiring captive/hinged relamping covers and no exposed live parts during lamp changes. 410.140(C) addresses live parts of the luminaire generally (not the lampholder/relamping act itself), so it's the closest but wrong distractor.