Let's look at fixture layout from two perspectives. First, where will the poles be placed in relation to the parking lot or road? Secondly, how far apart should they be?
A discussion of advantages and disadvantages for pole location is appropriate to discuss the first perspective. For parking lots, you usually have a choice between locating poles around the perimeter or within the area itself.
Interior location -
Advantage: You can generally use fewer poles which will reduce installation costs.
Disadvantages: 1) Spill light can be more of a problem, and, 2) the poles become obstacles
for drivers to avoid.
Perimeter location -
Advantage: Less spill light into adjacent areas.
Disadvantage: For large parking lots, it may not be possible to light the area adequately
with perimeter poles.
To answer the second question regarding how far apart to place parking lot poles, a good rule of thumb is the two by four rule. For good parking lot uniformity of illumination, place poles no further than 2 times the mounting height from the corners and no more than 4 times the mounting height from each other.
For interior pole location the same rules apply, no more than 2 times the mounting height from the edges and no more than 4 times the mounting height from each other.
And Furthermore . . .
