Does this credit only apply to lighting fixtures installed on masts with mounting heights ?

The credit language is clear.

"all exterior luminaires located inside the project boundary (except those listed under “Exemptions”)"

All exterior lighting fixtures that are within the LEED PROJECT Boundary are included. This means all fixtures that are mounted on the building or on the ground.

There are some EXEMPTIONS that are listed at the end of the credit:

• "specialized signal, directional, and marker lighting for transportation;
• lighting that is used solely for façade and landscape lighting in MLO lighting zones 3 and 4, and is automatically turned off from midnight until 6 a.m.;
• lighting for theatrical purposes for stage, film, and video performances;
• government-mandated roadway lighting;
• hospital emergency departments, including associated helipads;
• lighting for the national flag in MLO lighting zones 2, 3, or 4; and
• internally illuminated signage."

Dear Sara,

spotlights installed inside trees can considered as landscape lighting and if automatically turned off from midnight until 6 a.m can be excluded. All other lights are to be included for compliance.

Sara,

correct. your project must be in LZ3 to use the exemption

Right, Sara. Your project must be in LZ3, LZ4 to use the exemption