Selecting The Optimum Standard

FOUR FACTORS ESSENTIAL TO SELECTING THE OPTIMUM STANDARD

1.) HEIGHT: Is determined by the type and number of luminaires required to produce the specified minimum foot candles and acceptable distribution patterns.

2.) E.P.A.: Effective Projected Area is determined by multiplying the total number of square feet in surface area of all the equipment mounted on the standard (luminaire, brackets, arms, etc.) that is silhouetted against the force of the wind by a drag coefficient.

3.) WEIGHT: Is the total weight of all equipment (luminaires, brackets, arms, etc.) that is to be mounted on and supported by the standard.

4.) WIND AREA: Refers to the Wind Velocity Map, this is a 50 year mean recurrence interval map. The wind values found on the map represent wind velocities 30 feet above the ground. Each standard in this catalog has been designed to support the listed E.P.A. and weight load silhouetted to the force of the wind velocities listed. The design also allows for a 1.3 gust factor.

NOTE: If the standard is to be mounted above grade level, contact your Lexington Representative for custom loading analysis.

A shielding factor may be used when calculating the total E.P.A. for some multiple luminaire configurations.

For example, assume a single luminaire E.P.A. of 2.0:

Selecting the optimum standard for your requirements demands specific information.

Required is:

1) Mounting Height, 2) Total E.P.A. (Effective Projected Area in square feet), 3) Total Weight to be supported, and 4) Wind velocity at the job site (verify with wind velocity map and specifying engineer).

Assume you require: 1) 30 ft. mounting height, and 2) Two luminaires with an E.P.A. of 1.9 each plus a two-tenon bracket with an E.P.A. of 0.78 (2 x 1.9=3.8 plus 0.78=4.58 total E.P.A.) and 3) Total weight-two luminaires at 40 lbs. each = 80 lbs. plus 11 lbs. for the two tenon bracket = 91 lbs., and 4) 80 MPH wind velocity location.

Required: 30 ft. height, 4.58 E.P.A., 91 lbs. weight, 80 MPH wind velocity. Refer to Page 1-1, 20 to 50 ft. Round Tapered Poles - Top Mounted Luminaires. Optimum standard for these requirements is model 2908-40705T4. If you would like assistance contact your Lexington Representative.