LLC Material Selection & Properties 5

Question 1

When specifying cable for a 150-foot low-voltage landscape lighting run with a 10-amp load, which wire gauge minimizes voltage drop below 5%?

Accepted Answer

10 AWG

Answer

A 10 AWG wire over a 150-foot run at 10 amps keeps voltage drop to approximately 3.5% at 12V, staying within the 5% maximum threshold.

Question 2

Which fixture housing material is least suitable for installation in areas where soil pH is below 5.0?

Accepted Answer

Cast aluminum

Answer

Cast aluminum corrodes more rapidly in highly acidic soils (pH below 5.0) because the natural oxide layer breaks down, requiring additional protective coatings.

Question 3

What material property determines the lumen maintenance rating (L70) of an LED landscape light fixture over its lifespan?

Accepted Answer

LED junction temperature management

Answer

LED junction temperature is the primary factor determining lumen depreciation; higher operating temperatures accelerate light output loss and shorten time to L70.

Question 4

For outdoor landscape lighting near a swimming pool within 5 feet of the water edge, which fixture material classification is required per NEC Article 680?

Accepted Answer

Submersible listed

Answer

NEC Article 680 requires that luminaires within 5 feet of pool water edges be listed for submersible use to protect against incidental submersion.

Question 5

Which characteristic of tempered glass makes it superior to regular annealed glass for use in recessed in-ground landscape fixtures?

Accepted Answer

Breaks into small, less hazardous pieces

Answer

Tempered glass is heat-treated to break into small, rounded fragments rather than sharp shards, making it safer for in-ground fixtures subject to foot traffic.

(LLC) Landscape Lighting Certification Practice Test

(LLC) Landscape Lighting Certification Practice Test

LLC Material Selection & Properties 5