UV irradiation attacks conventional plastics (e.g. polyamide 6.6). This causes faster aging and embrittlement, increasing the risk of plastic cable ties breaking and falling off. Depending on UV radiation exposure, this can happen after just one year or in 2 - 3 years at the latest. "For outdoor use, I recommend fasteners made of PA66W material. These are UV-stabilized and therefore ideally suited for outdoor use," says Artur Hofer, Senior Product Manager Germany Cable Ties and Fixings.
What distinguishes the UV-stabilized material from conventional plastics?
The basic material, polyamide 6.6, of a plastic cable tie is always the same. The special feature of the PA66W material is the addition of carbon black. According to ASTM standard D6779, the percentage for a UV-stable cable tie is 2%. Carbon black ensures that UV rays cannot penetrate deep into the material, keeping the core of the cable tie intact. By adding carbon black, weather-resistant cable ties and fastening solutions are always black.
Furthermore, the material is characterized by its very good tensile strength and an operating temperature of -40 °C to +85 °C. In summary, the material represents ideal properties for outdoor use, at least for the North European region - but more on that later.
Cable tie T50 in combination with a foot part for fixing cables to solar systems.
What are the effects of UV damage when using conventional cable ties?
UV rays cause the material to age more quickly as it attacks the existing molecular chains. Due to the UV exposure, the bonds are separated, making the material brittle. In the worst case, depending on the UV exposure and the period of time, the conventional cable tie can break and fall off even under the slightest stress, so that installed cables hang freely, for example. A breakage or a brittle cable tie in the installed state is not visible, so electricians do not actively replace cable ties in their maintenance activities. Only when the cables have fallen down, the subsequent installation follows, which causes additional costs.
What are the costs compared to conventional cable ties?
Compared to conventional natural cable ties, the UV-resistant cable ties are more expensive to purchase. In the long term, the price is more favorable. For example, if a system runs for 10 years, a UV-stabilized cable tie would be sufficient. Natural cable ties, on the other hand, would have to be replaced several times during their service life, on average every 2 years in northern Germany. This causes additional costs for the maintenance by the electrician besides the repeated purchase.
What experiences have customers had using UV-stabilized materials?
The previous arguments clearly show that the UV-stabilized cable ties are indispensable, especially in the installation of PV and solar systems. The systems are designed for a service life of up to 30 years, so maintenance work on fastening elements can be minimized with the help of UV-stabilized cable ties, thereby saving costs.
But customers in the wind industry have also switched to PA66W cable ties. For example, they are used to install cables in wind turbines. The wind turbine is delivered to the construction site in several individual parts, some of which are stored for 6 - 12 months and exposed to the weather. Previously, the manufacturer worked with conventional cable ties and could already detect brittle cable ties over the period of time - and the turbine was not even completed then.
PA66W cable ties in use on wind turbines
How can I make sure I am using a UV stabilized cable tie?
Visually, there is no difference between a conventional, black cable tie and a UV-stabilized cable tie. To ensure whether the cable tie to be installed is made of the PA66W material, there is the so-called "hammer test". With the aid of a hammer, the strap end of a cable tie is knocked flat and held up to the light. With a conventional, dyed cable tie, the end is transparent. The carbon black content of a UV-stabilized one ensures that no light penetrates and the end of the tie remains black.
Which products does our product manager recommend for the area around PV and solar systems?
In Germany, and especially in the North German region, cable ties and fasteners made of PA66W are ideally suited.
"In addition to cable ties, we have developed other products made of PA66W in product management that cover a large need of every electrician," Artur Hofer tells us.
Among them, cable ties in different sizes and with different foot parts, e.g. with expansion anchor, lamella foot or weld stud receptacle, HellermannTyton's portfolio also offers adhesive bases and clamps made of PA66W. Especially our edge clips and clamps of the Ratchet P-Clamp series are best suited for installation on PV and solar systems. For more information, please take a look at our topic area about solar and PV systems.
But also sockets for screwing or gluing should not be missing in the suitcase of an installer. The adhesive bases are supplemented by UV-stabilized adhesive. Other areas of application can be, for example, the installation of fairy lights or the fastening of flower tendrils outdoors. In general, UV-resistant fasteners are beneficial for any installations of cables and wires on the roof, on the house or in the garden.
The further south we move in Europe, the higher the UV exposure becomes.
"For these regions, I recommend other materials such as polyamide 11 or stainless steel. At the present time, polyamide PA66W is still sufficient for the German region," says Artur Hofer.
Cable ties made of PA66W in solar systems.
The recommendations from the professional: the correct processing.
An important note is the correct processing. By this, the product manager means no installation below 0 °C. This tip is relevant for all polyamides, but tests show that polyamides with carbon black content are particularly susceptible. The dry air at low temperatures removes water from the polyamides, making dry cable ties more susceptible to breakage. Materials with carbon black content also disrupt the material, so processing should take place above 5 °C in the best case. Once the ties are installed, they can withstand temperatures as low as -40 °C without any problems.
