CLD Electrical Systems & Lighting Control 4

Question 1

A contractor plans to use a standard 600V-rated dimmer on a 277V circuit. What is the safety concern?

Accepted Answer

A 277V circuit requires a dimmer rated for at least 347V or the specific 277V application

Answer

Dimmers must be rated for the specific voltage of the circuit; a 277V application requires a 277V-listed dimmer, and 600V ratings do not automatically imply 277V compatibility.

Question 2

In emergency lighting design, what is the minimum duration that a battery-backed unit must maintain illumination per NFPA 101?

Accepted Answer

90 minutes

Answer

NFPA 101 (Life Safety Code) requires emergency lighting to operate for a minimum of 90 minutes after normal power failure.

Question 3

What control technique does 'forward phase' (leading edge) dimming use to reduce light output?

Accepted Answer

It chops the beginning of each AC half-cycle, delaying current flow

Answer

Forward phase (leading edge) dimming uses a TRIAC to cut off the start of each AC half-cycle, reducing the RMS power delivered to the load.

Question 4

A BACnet-integrated lighting control system allows the building automation system (BAS) to override lighting. Which scenario best justifies this integration?

Accepted Answer

To enable demand response — the BAS dims lighting during peak utility demand periods

Answer

BAS-to-lighting integration via BACnet enables demand response strategies where the BAS automatically reduces lighting loads during peak demand, cutting utility costs.

Question 5

Which wire gauge has a higher ampacity: 12 AWG or 10 AWG copper conductor in conduit at 75°C rating?

Accepted Answer

10 AWG — lower AWG number indicates larger wire diameter and higher ampacity

Answer

In the AWG system, lower numbers indicate larger wire diameters; 10 AWG copper is rated for 35A versus 20A for 12 AWG at 75°C per NEC Table 310.16.

(CLD) Certified Lighting Designer Practice Test

(CLD) Certified Lighting Designer Practice Test

CLD Electrical Systems & Lighting Control 4