100+ Free NCQLP LC Practice Questions

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Question 1

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A luminaire's spacing criterion (SC) is listed as 1.4 and it is mounted 8 ft above the work plane. What is the maximum recommended center-to-center spacing for acceptable uniformity?

16.0 ft

11.2 ft

8.0 ft

5.7 ft

to track

2026 Statistics

Key Facts: NCQLP LC Exam

180

Scored Questions

NCQLP

4 hrs

Exam Time

NCQLP

Case-Study Items

NCQLP

Sections

NCQLP

PSI

Administrator

NCQLP

Scaled

Passing Score

NCQLP

The NCQLP LC exam has 180 scored multiple-choice questions answered in 4 hours, including 80 job-related case-study items. It covers lighting fundamentals, calculations and photometrics, sources and luminaires, controls, daylighting, energy codes (such as ASHRAE 90.1 LPD), economics, maintenance, and applied design. NCQLP uses a scaled passing score and does not publish a fixed pass percentage. The exam is administered by PSI for the National Council on Qualifications for the Lighting Professions.

Sample NCQLP LC Practice Questions

Try these sample questions to test your NCQLP LC exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which photometric quantity describes the luminous flux incident per unit area on a surface, and what is its SI unit?

A.Illuminance, measured in lux

B.Luminance, measured in candelas per square meter

C.Luminous flux, measured in lumens

D.Luminous intensity, measured in candelas

Explanation: Illuminance is the density of luminous flux arriving on a surface, defined as lumens per unit area; the SI unit is the lux (lm/m2) and the IP unit is the footcandle (lm/ft2). It is what light meters read at the work plane.

2A point source produces 25 footcandles on a surface 4 ft directly below it. Using the inverse-square law, what is the illuminance at a point 8 ft directly below the same source?

A.100 footcandles

B.6.25 footcandles

C.12.5 footcandles

D.50 footcandles

Explanation: The inverse-square law states illuminance is proportional to 1/d2. Doubling the distance from 4 ft to 8 ft quarters the illuminance: 25 / (8/4)^2 = 25/4 = 6.25 fc. This applies to a perpendicular surface directly beneath a point source.

3In the lumen (zonal-cavity) method, what does the Coefficient of Utilization (CU) represent?

A.The ratio of luminaire rated lumens to lamp rated lumens

B.The fraction of lamp lumens that reaches the work plane

C.The fraction of luminaire lumens that reaches the work plane, accounting for room geometry and surface reflectances

D.The ratio of maintained to initial illuminance over the cleaning cycle

Explanation: The CU is the fraction of the bare-lamp (or luminaire) lumens that ultimately arrives on the work plane. It depends on luminaire distribution, room cavity ratio, and the reflectances of ceiling, walls, and floor, and is read from manufacturer CU tables.

4Using the lumen method, the number of luminaires required equals (target illuminance x area) divided by which expression?

A.Lumens per luminaire x room cavity ratio

B.Lamp wattage x CU x LLF

C.Lumens per luminaire divided by CU x LLF

D.Lumens per luminaire x CU x LLF

Explanation: N = (E x A) / (lumens per luminaire x CU x LLF). The denominator is the effective maintained lumens each luminaire delivers to the work plane, so dividing the total required lumen-area product by it yields the luminaire count.

5Correlated Color Temperature (CCT) of a white light source is expressed in kelvin. A source rated 2700 K compared with one rated 5000 K will appear:

A.Warmer and more yellow/red

B.Identical in appearance because CRI governs color

C.Greener due to higher duv

D.Cooler and bluer

Explanation: Lower CCT values appear warmer (more yellow/red), while higher CCT values appear cooler (bluer). A 2700 K source resembles incandescent warmth; 5000 K approaches midday daylight. CCT describes chromaticity appearance, independent of color rendering.

6The Color Rendering Index (CRI, Ra) of a light source is determined by:

A.Comparing the chromaticity of the source to a 6500 K daylight standard only

B.Measuring how faithfully the source renders a set of standardized color samples relative to a reference illuminant of the same CCT

C.Averaging the source efficacy across the visible spectrum

D.Counting the number of spectral peaks in the source output

Explanation: CRI (Ra) averages the color-shift of the first eight standardized CIE test color samples when lit by the source versus a reference illuminant of the same CCT (a blackbody below 5000 K or a daylight phase above). A score of 100 indicates no shift.

7Luminous efficacy of a light source is best defined as:

A.The illuminance produced at one meter from the source

B.The total lumens a lamp produces over its rated life

C.The ratio of luminous flux output (lumens) to electrical power input (watts)

D.The fraction of lamp lumens emitted by the luminaire

Explanation: Efficacy is lumens per watt (lm/W), measuring how efficiently a source converts electrical power into visible light. Higher efficacy means lower energy use for a given light output, a key driver of LED adoption and energy-code compliance.

8A luminaire is rated at 5000 lumens. The bare lamps inside are rated at 6250 lumens total. What is the luminaire (fixture) efficiency?

A.0.625

B.0.50

C.1.25

D.0.80

Explanation: Luminaire efficiency = luminaire output lumens / bare-lamp lumens = 5000 / 6250 = 0.80, or 80%. The 20% loss is absorbed by reflectors, lenses, and housing. This ratio is reported in photometric reports as total luminaire efficiency.

9On a candlepower distribution (polar) curve for a luminaire, the radial distance from the center at a given angle represents:

A.Luminous intensity in candelas in that direction

B.Luminance in cd/m2 of the emitting surface

C.Total luminous flux in lumens in that zone

D.Illuminance in footcandles at that angle

Explanation: A candlepower (candela) distribution curve plots luminous intensity versus angle. The radial length at each angle is the candela value emitted in that direction, characterizing whether a luminaire is direct, semi-direct, diffuse, or asymmetric.

10The total Light Loss Factor (LLF) used in maintained-illuminance design is the product of recoverable and nonrecoverable factors. Which of the following is a RECOVERABLE light loss factor?

A.Ballast factor

B.Luminaire Dirt Depreciation (LDD)

C.Voltage-to-luminaire factor

D.Luminaire ambient temperature factor

Explanation: Luminaire Dirt Depreciation (LDD) and Lamp Lumen Depreciation (LLD) and room-surface dirt depreciation are recoverable factors because cleaning or relamping restores output. Nonrecoverable factors (ballast factor, ambient temperature, voltage, tilt) are inherent to the installation.

About the NCQLP LC Exam

The NCQLP Lighting Certified (LC) examination is a 4-hour, two-section test of 180 scored multiple-choice questions (plus unscored pretest items) administered by PSI for the National Council on Qualifications for the Lighting Professions. It validates competence across lighting fundamentals, calculations and photometrics, light sources, luminaires and controls, daylighting, energy codes, economics and maintenance, and applied lighting design. Eighty of the questions are job-related case studies grouped around shared project scenarios.

Questions

180 scored questions

Time Limit

4 hours

Passing Score

Scaled passing score (fixed percentage not published)

Exam Fee

Set by NCQLP (see current candidate handbook) (NCQLP (administered by PSI))

NCQLP LC Exam Content Outline

20%

Lighting Fundamentals and Vision

Photometric quantities, the eye and vision, mesopic effects, color temperature and rendering, and light physics

25%

Lighting Calculations and Photometrics

Lumen (zonal-cavity) method, point method, inverse-square and cosine laws, light loss factors, photometric files, unit conversion

20%

Light Sources, Luminaires and Controls

LED and lamp technology, efficacy and binning, luminaire optics and ratings, dimming, DALI/DMX and addressable controls

20%

Daylighting, Energy Codes and Standards

Daylight factor, sDA/ASE, glazing, ASHRAE 90.1 LPD and control requirements, IES recommended practices

15%

Design Application, Economics and Case Studies

Interior/exterior/roadway/emergency design, economics and maintenance, professional practice, job-related case studies

How to Pass the NCQLP LC Exam

What You Need to Know

Passing score: Scaled passing score (fixed percentage not published)
Exam length: 180 questions
Time limit: 4 hours
Exam fee: Set by NCQLP (see current candidate handbook)

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

NCQLP LC Study Tips from Top Performers

1Memorize the photometric quantities and units (lumen, candela, lux/footcandle, cd/m2) and how they relate

2Practice the lumen (zonal-cavity) method end to end, including CU, RCR, and light loss factors

3Drill the point method with the inverse-square and cosine laws on tilted surfaces

4Learn IES recommended practices by application (RP-1 offices, RP-8 roadway, RP-20 parking)

5Know ASHRAE 90.1 LPD calculations, automatic shutoff, and daylight-zone control requirements

6Understand LED metrics: efficacy, LM-79, LM-80/TM-21, L70, CRI/TM-30, CCT, and binning

7Approach case studies by fixing the project context once and applying it across the grouped questions

8Practice unit conversions (1 fc = 10.76 lux) and quick energy-cost/payback calculations

Frequently Asked Questions

How many questions are on the NCQLP LC exam?

The LC exam has 180 scored multiple-choice questions delivered in two sections, plus a number of unscored pretest questions. Eighty of the scored questions are job-related case studies, where a shared instruction and project documents apply to a group of related questions. Candidates have 4 hours to complete the exam.

How long is the NCQLP LC exam and who administers it?

The LC exam is a 4-hour examination administered by PSI on behalf of the National Council on Qualifications for the Lighting Professions (NCQLP). The questions span recall, comprehension/application, and analysis cognitive levels, with most items requiring you to apply lighting knowledge to design and project scenarios rather than simply recall facts.

What topics does the NCQLP LC exam cover?

The LC exam covers lighting fundamentals and vision, lighting calculations and photometrics (lumen method, point method, light loss factors), light sources and lamps, luminaires and controls, daylighting, energy codes and standards such as ASHRAE/IES 90.1, lighting economics and maintenance, and applied design for interior, exterior, roadway, and emergency lighting.

What is the passing score for the LC exam?

NCQLP uses a scaled passing score determined through standard psychometric methods rather than a published fixed percentage. Scores are reported as pass or fail. Because the exam is criterion-referenced, candidates should focus on mastering the published content areas in the candidate handbook rather than targeting a specific percentage.

How should I approach the case-study questions?

Each case study presents a shared instruction and project materials, such as drawings, a lighting schedule, and a control narrative, for a group of related questions. Read the common scenario carefully, establish the project context (space types, illuminance targets, codes, and controls), and apply that context consistently to every linked question in the group.

How do I prepare for the NCQLP LC exam?

Many candidates use the IES LC study group and the IES Lighting Handbook alongside the NCQLP candidate handbook, which lists the reference materials and content areas. Practice lumen-method and point-method calculations, learn IES recommended practices and ASHRAE 90.1 lighting requirements, and work many application and case-study questions to build speed and accuracy.