Photometric Lighting Design & The Quality of Light.

The "average" amount of light or the required foot-candle level should not be the overriding factor when evaluating lighting fixtures for your restaurant. The human eye does not see these "averages". Rather, the eye perceives contrasts between areas of brightness and darkness. Because of this, a restaurant site with even, uniform illumination creates the perception of being brighter than a site with pools of light and pockets of darkness.

RLLD's vertical burn systems provide uniform illumination throughout your parking lot by eliminating these contrasts of light and dark. To understand the concept of vertical burn, it helps to compare two lighting systems using a gray scale shading analysis.

System A Horizontal Burn - 10 fixtures, 6 poles System A uses conventional horizontal

burn fixtures, commonly known as shoeboxes. This system creates hot spots, resulting in a perception of poor lighting by your customers and employees. If not properly aimed, shoebox fixtures can cause glare and EPA (wind-load) problems. 

System B Vertical Burn - 8 fixtures, 4 poles System B utilizes the advanced vertical burn lamp / reflector technology to maintain a high average level of illumination and uniformity.  Properly controlled, a lamp placed in this vertical position can distribute light more evenly over a larger amount of space than a horizontally positioned lamp because there is more surface for light to escape. Vertical positioning helps minimize "hot spots" and pockets of darkness while reducing glare.

Because light is distributed over a larger area, fewer fixtures and poles are typically

needed, thus reducing installation, energy and maintenance costs.

HOW TO MEASURE LIGHT

All light readings should be taken at grade. Do not attempt to take readings at "waist height" as this will be inconsistent and your body will cast shadows on the meter, reducing / distorting the readings.

Place the light meter on the pavement in an area where there are no obstructions. Lighting is purely additive and good lighting relies on the contribution of light from all fixtures to achieve a given foot-candle level. Do not place the meter in "the shadow" of trees, menu boards, or other obstructions.

When reading the levels on the light meter use extreme care to be sure that your body isn't bstructing (blocking) light from the meter. To verify your location in relationship to the meter, check to see that your shadow (no matter how faint) isn't falling on the face of the meter.

The Sylvania Digital Light Meter will give you a reading in foot-candles striking the quarter size white viewing screen. It measures only light striking a surface, it does not measure "brightness" or light reflecting off of surface. A light meter setting on a black surface will read the same foot-candle level as a light meter on a white surface. The white surface will appear much "brighter" because it is eflective, but the amount of light striking the surface would be the same.

Light Meter

Surveying Your Location

An accurate site survey is a critical step in planning an effective and economical lighting system. Investing time up front to sketch and plot out your property enables our Technical Services department to determine the best lighting system for your requirements. In addition, a site survey helps the contractor prepare for installation.

How to Survey Your Site

Start with a scaled site plan or   simply sketch out your site on  a clean sheet of paper. Now that you have drawn the basics (building and parking lot area), sketch the surroundings:

- Property lines

- Perimeter curbs

- Sidewalks

- Parking spaces

- Trash enclosures

- Adjacent properties

Provide measurements for the building, curb/property line and interior curbs. Be sure to highlight any obstructions such as trees or landscaping. Once you have these basics, note your existing lighting for the parking lot, building and landscape. Be sure to provide as many specifics as you can:

- Fixture dimensions & condition

- Pole dimensions & condition

- Lamp type & wattage

- Wire & conduit size

- Anchor bolt positioning to the lot; square or diagonal

- Measure anchor bolt size and center to center spacing

Don't forget to note signs and drive-thru menu boards. Each of these elements contributes to the overall lighting of your property. Finally, attach photographs if possible. Remember, doing this preliminary work up front will make system planning, ordering and installation run smoothly.

Sample Commercial Restaurant Parking Lot Lighting Survey Measurements.

SMALL STREET SIDE

EXISTING:

3-400 WATT HPS FIXTURES ON 4” X 18’ POLE. 3/4” ANCHOR BOLTS ON 7 -3/4” CENTERS.

SQUARE TO LOT ON 2’ BASE.

POLE, ANCHOR BOLTS AND BASE IN GOOD CONDITION.

EXISTING:

4-400 WATT HPS FIXTURES ON 5” X 22’ POLE.

1” ANCHOR BOLTS ON 7-3/4” CENTERS DIAGONAL TO LOT ON 2’ BASE.

POLE IS RUSTY/POOR CONDITION.

ANCHOR BOLTS AND BASE IN GOOD SHAPE.

EXISTING:

2-400 WATT HPS FIXTURES ON 4” X 18’ POLE.

5/8” ANCHOR BOLTS ON 6-3/4” CENTERS SQUARE TO LOT ON 2’ BASE.

POLE, ANCHOR BOLTS AND BASE IN BAD CONDITION.