When selecting a pole, it is necessary to consider wind pressure in the given location, Effective Projected Area (EPA), and the pole height and shape to make an appropriate pole selection. A light standard is an engineered structure, and consists of the anchors, pole, fixture and any additional loading, such as banners. All information will provide the best solution for your customer and add to the longevity of the project.
Since CSA took over the design standards from AASHTO in 2000, many changes have taken place in the structural evaluation of a pole design. Instead of the mph or kph wind speeds traditionally employed, wind is now specified in terms of pressures in Pascal’s. Critical in the design with CSA is fatigue, which is a new requirement with CSA, and mandatory for approval as of June 2015. Wind pressures taken from the CSA S6 published tables are at the back of this PSG, and corresponds to exposure over smooth terrain at a height of 33 ft. (10 meters) above the ground. Poles under 15m are to be designed using 1/25 wind pressures, while poles over 15m use 1/50. Contact Polefab for cites that are not in the table supplied. To convert Square feet to square metres, divide sq ft / 10.76. Example, 2sq ft/10.76 = .185m2.
Effective Projected Area
The Effective Projected Area of lighting equipment is expressed in square metres, however square feet is still in use. It is a calculated figure that when multiplied by the wind pressure represents the force or load exerted on the pole. It is calculated by determining the maximum surface area (length x width), that would be subjected to a wind force, also taking into account the coefficient of drag. Projected areas for loading shall be the fixture EPA multiplied by the fixture quantity. In the case of 4 fixtures @ 90 degrees, you may multiply by 3.
Selecting a Pole
Other than lighting going on a pole, there are many things to take into account. A few are listed below, and are typically critical factors in the design, pricing and supply of a pole. Please review;
Elevated mounting heights
- Advise if poles are mounted on a parking garage, building, bridge, etc. Wind pressures increase with elevation, and need to be taken into account to correctly size poles.
Project specific needs
- If your customer has specifications that may override our standard, they need to be supplied to properly take special provisions into account.
Car Dealerships, and signage
- Car dealerships often add aftermarket signage and overhead streamers etc. to the poles once installed. Customers should ask as to what the future plans are as far as signs, banners, etc. to properly design the poles. One should exercise caution to release anchors too early, as a design change may render the anchors & footing useless with the proper design.
- Simply, any pole with overhead wiring. Typical poles are not designed to withstand the forces form overhead tension, and it should be considered, even with temporary wiring.
Banners, flower holders
- Poles may be designed to handle a multitude of add-ons, all that is needed are the details of the items. We can supply banner arms, fixture arms, flower pot mounts, street sign brackets, etc. just send along a detail, and we can quote you. Below is a list of answers we will need to design effectively.
- Banner length x width, and if solid, meshed, holed or otherwise
- If you want the bottom on the banner to be pinned in 1 corner or fully supported
- Banner mounting height, either to the bottom or centre line
- Any add ons should be treated the same way as above, EPA, weights & locations.
- Be aware of the existing anchor diameter & BCD, the new pole you may want to replace may not fit
- Additionally, the Yield of the existing bolts, and condition of the footing may be unknown. These are risks to be evaluated. If anchor yield is unknown, Fy may be reduced to 36ksi.
- It is common for customers to request an engineering review if they would like to add banners or additional loading to an existing pole. We would be pleased to discuss this with you.
In pole transformers
- Many fixtures have externally mounted transformers that customers would like mounted in the pole, at the top, at the bottom, or in a custom base. Please keep this in mind at the quote stage, and your transformer may not fit inside the pole. Transformer access holes are typically large, non-standard and be custom quoted.
These are a few of the project issues that when taken care of correctly at the beginning of a project will reduce post PO problems. If you have any questions on pole design, additions, or what can be done to make things simpler, please do not hesitate to contact us for a solution.
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