LLC Material Selection & Properties 4

Question 1

Which heat sink material provides the best thermal conductivity for LED modules in high-ambient-temperature installations?

Accepted Answer

Extruded aluminum

Answer

Extruded aluminum has excellent thermal conductivity (205 W/m·K), is lightweight, and allows complex fin geometries that maximize heat dissipation from LED modules.

Question 2

When selecting spike stakes for fixture mounting in clay soil, which material resists bending under repeated frost heave cycles?

Accepted Answer

304 stainless steel

Answer

304 stainless steel spike stakes combine corrosion resistance with sufficient yield strength to withstand repeated frost heave forces without permanent deformation.

Question 3

What is the recommended minimum burial depth for direct-burial landscape lighting cable to protect against routine lawn maintenance damage?

Accepted Answer

6 inches

Answer

NEC and industry standards recommend a minimum burial depth of 6 inches for low-voltage landscape lighting cable to avoid damage from typical gardening and lawn care tools.

Question 4

Which type of photocell material degrades fastest when exposed to prolonged UV radiation in outdoor landscape installations?

Accepted Answer

Cadmium sulfide cells

Answer

Cadmium sulfide (CdS) photocells experience significant drift and degradation with prolonged UV exposure, unlike silicon-based replacements that are more stable.

Question 5

For bronze landscape fixtures, what surface treatment best preserves the original appearance while allowing the metal to breathe?

Accepted Answer

Renaissance wax

Answer

Renaissance wax is a microcrystalline wax that protects bronze from oxidation while allowing slight breathing, used by conservators to preserve metal artifacts.

(LLC) Landscape Lighting Certification Practice Test

(LLC) Landscape Lighting Certification Practice Test

LLC Material Selection & Properties 4