CLD Luminaire Selection 3

Question 1

A luminaire specification calls for an 'L70' rating of 50,000 hours. What does L70 describe?

Accepted Answer

The luminaire retains 70% of its initial lumens at 50,000 hours

Answer

L70 is the lumen maintenance rating indicating the point at which the LED light source retains 70% of its initial lumen output.

Question 2

For a corridor emergency egress path, which IES luminaire classification best describes a luminaire directing light primarily downward at low angles along a pathway?

Accepted Answer

Type II

Answer

Type II distribution provides a lateral spread suited for corridors and walkways, directing light ahead along a path from a side-mounted position.

Question 3

A designer selects a luminaire with a Unified Glare Rating (UGR) of 19 for an open office. What does this value indicate?

Accepted Answer

The luminaire meets the typical UGR <19 office glare limit

Answer

UGR <19 is the standard threshold for office spaces per EN 12464-1, and a UGR value of exactly 19 sits at the acceptable boundary for typical office tasks.

Question 4

Which luminaire mounting configuration would a CLD specify to minimize veiling reflections on computer screens in an open office?

Accepted Answer

Indirect or direct/indirect pendants directing light toward the ceiling

Answer

Indirect and direct/indirect pendants bounce light off the ceiling, creating a diffuse luminous environment that minimizes specular reflections on monitor screens.

Question 5

A theatrical performance space requires luminaires capable of tight beam control, color mixing, and remote dimming. Which category best fits this application?

Accepted Answer

Entertainment/theatrical ellipsoidal luminaires

Answer

Ellipsoidal luminaires (also called Leko or Source Four fixtures) provide precise beam shaping, gobo projection, and are designed for theatrical color and dimming control.

(CLD) Certified Lighting Designer Practice Test

(CLD) Certified Lighting Designer Practice Test

CLD Luminaire Selection 3