Lighting FAQ, NLC

Lighting FAQ

Practical answers from NLC engineers to the questions we hear most, plus a glossary of the terms you meet on datasheets and in specifications.

Questions our engineers answer

Click any question to expand the answer. Use the search to filter questions and glossary terms together.

What is colour temperature (CCT) and which one should I choose?
CCT describes how warm or cool white light looks, measured in kelvin. As a rule of thumb: 2700-3000K suits hospitality and residential spaces, 3500-4000K suits offices, retail and healthcare, and 5000K and above suits industrial and outdoor task areas.
What CRI do I need?
CRI measures how faithfully colours appear under a light source, out of 100. CRI 80 is the norm for general commercial spaces; specify CRI 90 and above where colour matters, such as retail, galleries, hospitality, and clinical examination areas.
Lumens or watts: which number tells me how bright a luminaire is?
Lumens. Watts only measure the electrical power drawn. Divide lumens by watts to get efficacy (lm/W), the number that tells you how efficiently a luminaire turns energy into light.
How many lux does my space need?
Typical targets from EN 12464-1: 500 lx for office desks, 300 lx for retail sales floors, 200 lx for warehouse aisles, 100 lx for corridors. The Lux calculator on our Engineering Tools page sizes a room in seconds.
What is the difference between IP and IK ratings?
IP describes protection against dust and water: IP65 is dust-tight and jet-proof, IP67 survives temporary immersion. IK describes impact resistance from IK00 to IK10. Outdoor and industrial fixtures should carry both ratings on the datasheet.
What is UGR and when does it matter?
UGR quantifies discomfort glare on a scale of roughly 10 to 30, lower is better. Offices with screen work should be designed to UGR 19 or below; sports halls and industrial spaces have their own limits.
What does L70 50,000 hours mean?
It is the point at which LED output has depreciated to 70 percent of its initial lumens: after 50,000 hours of operation the luminaire still emits at least 70 percent of the light it started with.
What is DALI and why specify it?
DALI is the open digital protocol for lighting control: each driver is individually addressable, dimmable, and reports its status. DALI-2 adds certified interoperability. Specify it where you need scenes, daylight harvesting, or per-fixture monitoring.
Are NLC luminaires suitable for Saudi outdoor conditions?
NLC designs for the local environment: high ambient temperatures, dust, and coastal humidity. Always check the datasheet operating temperature range and IP rating against your site conditions, and ask our engineers when in doubt.
What is PPFD and why do plants need special lighting?
Plants respond to photons in the 400 to 700 nm PAR range, not to brightness as our eyes see it. PPFD measures the photons landing on each square metre of canopy per second. See our Horticulture Lighting page, or size a project with the PPFD calculator.
How do I get NLC datasheets, IES files, or BIM content?
Datasheets are published on each product page. IES/LDT photometric files and Revit families are available on request: tell us the product and the project.
How do I write NLC products into my specification?
Use the Spec Writer on the Engineering Tools page: pick a product and copy a ready specification clause or BOQ line, with values taken from the official datasheets.
Can NLC support the lighting design for my project?
Yes. Our engineers support consultants and contractors with layouts, calculations, and product selection across the Kingdom. Use the contact form and share your drawings.
What is the difference between an emergency and an exit luminaire?
Exit signs mark the escape route and stay illuminated; emergency luminaires light the route itself when mains power fails, typically for at least 90 minutes from an internal battery. Check the civil defence requirements for your building type.

Lighting glossary

The terms you meet on datasheets and in specifications, one clear definition each.

Lumen (lm)

The total quantity of visible light a source emits.

Lux (lx)

Lumens per square metre: how much light lands on a surface.

Candela (cd)

Luminous intensity in a specific direction.

Efficacy (lm/W)

Lumens produced per watt consumed: the efficiency of a luminaire.

CCT (K)

Correlated colour temperature: how warm (2700K) or cool (6500K) white light appears.

CRI

Colour rendering index out of 100: how faithfully colours appear under the light.

TM-30

A modern colour rendition method using 99 samples, reported as fidelity (Rf) and gamut (Rg).

SDCM

Colour consistency between LEDs in MacAdam ellipse steps: 3 SDCM or less looks uniform.

UGR

Unified glare rating: discomfort glare on a scale of about 10 to 30, lower is better.

IP rating

Ingress protection against dust (first digit) and water (second digit), e.g. IP65.

IK rating

Impact resistance of the enclosure, from IK00 to IK10.

L70

Lifetime until light output falls to 70 percent of the initial value.

DALI

Digital addressable lighting interface: the open protocol for per-driver control.

0-10V dimming

Analogue dimming where a 0 to 10 volt signal sets the light level.

Beam angle

The angle within which the luminaire delivers its main light cone.

LPD (W/m²)

Lighting power density: installed lighting watts per square metre of floor.

LED driver

The power supply that converts mains to the regulated current LEDs need.

COB

Chip-on-board: many LED dies packaged as one high-intensity light-emitting surface.

Tunable white

Luminaires that vary CCT between warm and cool, often for circadian lighting.

Flicker

Rapid light modulation from the driver; low-flicker design matters for offices and sports.

PAR

Photosynthetically active radiation: the 400 to 700 nm range plants use.

PPF (µmol/s)

Photosynthetic photon flux: how many PAR photons a grow light emits per second.

PPFD (µmol/m²/s)

Photon flux density arriving at each square metre of plant canopy.

DLI (mol/m²/day)

Daily light integral: the total light a crop receives in a day.

Engineering Tools Horticulture Lighting Contact us