Detached buildings, cottages or buildings are connected using cable products. They can be laid underground, but this is costly. An air connection is most often used. It should be borne in mind that not every cable can be used for outdoor use. They must be designed to withstand harsh conditions. For example, exposure to ultraviolet radiation has a detrimental effect on cable insulation. In this case, damage does not occur immediately. It can only be determined after a few years. The insulation becomes brittle and crumbles. In some cases, it softens, leading to current leakage and short circuits. In this article, we will look at how to protect the cable from ultraviolet radiation, or as it is also called, from solar radiation.
Content:
- Exposure to solar radiation on cable
- Resistant conductor brands
- Cable protection
- Methods for protecting the insulation of internal cable conductors
- Additional UV protection
- Conclusion
Exposure to solar radiation on cable
Ultraviolet radiation acts gradually, it leads to a deterioration in the condition of the covering insulating layer. Under the influence of sunlight, accelerated aging of the surface layer occurs. As a result, the insulation changes its characteristics. Depending on the material, it becomes:
- Tough. Under mechanical stress, it cracks and crumbles. This is especially noticeable on the insulation of the cable cores.
- May change color or become sticky and lose its insulating properties.
Moreover, these changes occur initially only in the surface layer. Depending on the intensity of light, ultraviolet light changes the physicochemical characteristics of the insulation. Cracks appear and leakage current, resulting in a breakdown. This is typical when exposed to solar radiation and ozone - the strongest oxidizing agent.
The picture below shows the effect of prolonged exposure to insulation.
Resistant conductor brands
In order for the cable to serve for a long time, it is necessary to know what cable products can be used and how to protect it from solar radiation. The industry produces several types of cable that can be used to connect consumers.
In most cases, entry into a private house or cottage from a support is carried out by air. To do this, use a self-supporting insulated wire (SIP).
The insulation is made of cross-linked polyethylene, which is not exposed to ultraviolet light. The current-carrying conductors are made of aluminum. The connection is made using a bolted connection.
Less commonly, a VVSG cable is used for air connection. The cable is double insulated and UV protected.
To connect a barn or bath, use the most common cable VVGng-LS. The connection of the CIP wires with VVGng-LS is performed piercing clamps.
Cable protection
The surface insulation of the wires also suffers from the action of ultraviolet radiation.
If it is necessary to connect a detached building, they resort to additional protection:
- In the PUE, clause 2.3.19 (see. Chapter 2.3), it is said that if the facility is operated at latitude 650 and above, protection from solar radiation is not required. In the European part of Russia, these are the regions located north of Arkhangelsk and the Solovetsky Islands. In other cases, it is necessary. To do this, you can use cable products specifically designed for outdoor use.
- If the wiring is on the wall of the building, then it must be installed on the north side of the building. Be sure to cover with visors or gutters. They protect not only from the sun's rays, but also from snow, icicles and rainwater falling from the roof.
- The cable is suspended between buildings on a steel cable, and for protection from solar radiation, a corrugation or a metal pipe is used.
In air, wires are placed in a pipe if there is a possibility of mechanical damage.
The industry produces gray corrugation, it is intended for indoor use, and is made of PVC, it is not resistant to UV radiation. It cannot be used. But there is a black PVC corrugation resistant to ultraviolet radiation (check this fact in the product documentation from the manufacturer). There are other corrugations designed for outdoor use - made of high and low pressure polyethylene and is selected depending on the purpose. Such pipes are painted black or red, but do not focus on the color.. They resist well to external influences and can be operated in a wide temperature range from -400 up to +450C, and resistant to harmful solar radiation.
In order not to be mistaken with the choice, it is necessary to study the characteristics of the product. Before purchasing pipes, it is recommended to study the features of the corrugation. This can be done by reading the article on the site - https://samelectrik.ru/vidy-i-razmery-gofry-dlya-kabelya.html.
Often used to connect the power supply of detached buildings metal hose. It protects cable products from light, atmospheric precipitation in the form of snow adhesion, icing and provides additional mechanical protection. But it is short-lived, prone to corrosion, so this feature should be taken into account when using it.
Methods for protecting the insulation of internal cable conductors
Even if you lay a line in a corrugation or a metal hose, then when using the VVGng-LS cable to connect consumers in the open air, there is a problem with the internal insulation of the conductors. It is less resistant to ultraviolet radiation and degrades in a short period of time. We are talking about the cut ends of the cable at the connection to the main SIP.
Therefore, a pre-cut cable requires additional protection from sunlight. For this, sealed boxes are used. But they cannot be applied everywhere.
In addition, you can use shrink "gloves". The industry produces them in different diameters and configurations. The figure below shows "gloves" for a voltage of 220/380 V.
"Gloves" can be replaced heat shrink tubing with an adhesive composition. It is put on each core and end of the cable. It should be taken into account that the “glove” and tubes must be black. They are able to reliably protect the insulation from exposure destructive radiation.
Additional UV protection
You can protect the insulating layer with electrical tape. The stripped wires are completely wrapped with electrical tape. Closing and end of external insulation that is exposed to sunlight.
However, you should be aware that you can only use a special one, for example, 3M Scotch 780 or 3M Scotch 33, black electrical tape and provides protection from ultraviolet radiation. Note that not all black tapes are UV resistant.
Conclusion
The article will help you to choose the right cable products - https://samelectrik.ru/kabel-dlya-prokladki-na-ulice.html
And when connecting detached buildings, it is necessary to take into account the operating conditions and characteristics of the materials:
- SIP wires can be mounted without using additional UV protection. The manufacturer guarantees long-term operation in the open air without damage to the insulation; Since it has a steel core, a supporting metal cable is not required. However, the industry produces SIP-4. It represents a paired system. The main difference is the absence of a supporting core and a neutral wire. If this type of wire is used, it should be tied to a steel cable. The figure below shows SIP-4.
- The common VVGng-LS cable must be protected with a corrugation or a metal hose so that it does not get damaged by ultraviolet light. To avoid breaks from adhesion of snow or icing, be sure to hang it from a supporting steel cable.
So we looked at how to protect the cable from ultraviolet radiation. We hope the information provided has helped you choose the appropriate protection option for your conditions!
Related materials:
- How to protect the cable from mechanical damage
- Laying the cable along the facade of the building
- How to connect a self-supporting insulated wire with a copper wire
