CLD Controls and Dimming 5

Question 1

What is a 'tunable white' lighting system, and which control parameter does it add beyond dimming?

Accepted Answer

A system that adjusts both intensity and correlated color temperature (CCT) using separate or combined control channels

Answer

Tunable white systems independently control intensity and CCT—often via two channels or a specialized protocol—allowing the designer to adjust both how bright and how warm or cool the light appears.

Question 2

In a DALI system, what is a 'group' and how does it differ from an 'address'?

Accepted Answer

A group assigns multiple DALI devices to respond together to a single command, while an address targets one individual device

Answer

DALI allows up to 16 groups per segment; a group command dims all member devices simultaneously, while an individual address command targets only one of the 64 possible devices.

Question 3

An occupancy sensor fails to turn off lights after occupants leave. Which sensor setting should the designer adjust first?

Accepted Answer

Time delay (hold time)

Answer

The time delay (or hold time) setting determines how long the sensor waits after the last detected motion before switching off the lights; increasing it causes lights to stay on longer.

Question 4

What is the function of a 'vacancy sensor' as opposed to a standard 'occupancy sensor'?

Accepted Answer

A vacancy sensor requires manual activation to turn lights on but turns them off automatically when the space is vacant

Answer

A vacancy sensor (manual-on/auto-off) requires a person to manually turn on lights but switches them off automatically after vacancy, offering more energy savings and user control than auto-on occupancy sensors.

Question 5

Which energy code provision requires lighting controls to allow occupants to reduce lighting power by at least 50% in open office areas?

Accepted Answer

Occupant override (bi-level switching or dimming)

Answer

ASHRAE 90.1 and IECC require occupant-accessible controls (bi-level switching, dimming, or partial-off switching) that allow at least a 50% reduction in lighting power in open offices and similar spaces.

(CLD) Certified Lighting Designer Practice Test

(CLD) Certified Lighting Designer Practice Test

CLD Controls and Dimming 5