Wind Application to High Mast Lighting

[LJD]

I am investigating a high mast light basket failure. When applying the wind to the lights in the direction that the lights are in a line (spacing 3'oc), are there any good guidlines for taking into account shielding or reducing drag coeficients or do you apply the same wind to each individual light as you would when the wind is in the perpendicular direction?.

 

[samdamon]

LJD- My two cents is to not account for any shielding by adjacent lights. Reason being perhaps some of the lights may be damaged or removed by impact with a projectile during a wind event. Regards.

 

[VoyageofDiscovery]

Hi LJD,

I usually take a third off any horizontal member supporting the lights, if they form 360 degrees, that is occupy three sectors.

VOD

 

[squideye]

LJD Is this a lowering device (true himast pole)support? If so and this is a fairly recent installation, check with the device manufacturer for possible wind tunnel testing to give a more accurate EPA rating on luminaires and device. Most of the competent suppliers in the US have gone through this to become more competitive. If it is an older installation this matter will be your judgement. Remember that two items need nearly intimate proximity to truly give shielding. The tests I have seen vs the summing of areas seem to give less than 15% reduction of area. Typically shielding comes into play to a higher degree with sportslighting type structures with large mounting platforms and fixtues on both sides of the platform. If the failure is at the base weld there is a strong chance is it from fatigue. The most commonly seen is due to the use of a socket type double fillet weld rather than a full penetration butt weld. Sorry to be so wordy.