Masts play an essential role in modern lighting systems. While some lighting solutions might be able to make use of existing infrastructure—think of floodlights affixed to the roof of a football stadium, for instance—most require dedicated fixtures to be used. That’s where high masts come in, providing the requisite height needed to light an area effectively.
As is the case with any fixture above a certain height, masts are susceptible to wind and other forces. A strong enough breeze can cause a mast to shake and vibrate, which has an onward impact on structural stability. Long-term exposure to high winds can lead to everything from the appearance of small cracks through to all-out failure . And wind isn’t the only thing that can cause a mast to vibrate, either—as we’ll come to see.
Naturally, for safety reasons alone it’s important to minimise the risk of a mast failing as much as possible. With the addition of a heavy (and expensive) object like a luminaire, reducing that risk becomes even more important than it already is.
In this short guide, we’re looking at the impact of wind and vibration on masts and light poles—and how you can protect your own fixtures.
* A quick note before we begin: we’re using the term “masts” here, but the same guidance also applies to light poles and other support structures, too. *
Everyone knows that high winds can cause damage. Strong winds exert significant pressure, which can cause objects to bend, break, or collapse. Larger structures like buildings, signs, and trees are particularly susceptible to these dangers.
While the sheer force of a high wind can of course cause damage to a mast, however, the main issue here is actually that of vibration. When the wind blows against a mast, it causes the structure to vibrate—and those vibrations can be categorised in two different ways.
First and second mode vibration alike can be damaging to masts. Of the two, though, it’s second mode that tends to have the greatest impact. That’s all because of something called vibration frequency. The frequency of second mode vibration is typically much higher than first mode, enough to cause the kind of oscillation mentioned above. As a result, second mode vibration can eventually cause a mast to crack through what’s known as “material fatigue”.
That’s not to say that first mode vibration is harmless, however. While the vibration frequency may be lower, it will eventually result in material fatigue if left unchecked.
While windage is the primary cause of mast vibration, it isn’t the only one. At airports, for instance, the turbulence generated by aircraft can also have an impact. At sea ports and terminals, meanwhile, the movement of vehicles like gantry cranes and terminal tractors can lead to what’s known as “ground transmission”. This is when vibrations pass through the floor into a mast.
Absolutely, and this is where the specialist expertise offered by a provider like Midstream Lighting comes into play. A good lighting design will always take account of the local environment, and include masts that can withstand external factors like windage. Some of the factors that can have an influence here include:
As mentioned above, a good lighting partner will factor windage and vibration into their designs. To ensure that you’re getting the right solution for your needs, though, you may want to ask questions such as:
These should be carried out:
Key issues to check for include:
If you notice any of the above, then you should speak to your lighting provider as soon as possible. Reputable companies will always offer an extensive warranty for fixtures and luminaires, ensuring that you’re covered in the event of any issues.
Further questions on masts or lighting design? Please get in touch—we’re always happy to help. And, for more helpful advice, why not check out: