Impact of water inflow on cabling infrastructure:
1、 Impact on electronic equipment performance
Water ingress into the data cabling system may have a significant impact on the ability of the cable to support high-speed data applications. In some cases, cables that are close to the upper limit of the link length specified in the standard (and therefore close to the upper limit of the attenuation budget) may fail when encountering water ingress. This is because when the cable becomes wet, its insulation performance will change, which will affect the impedance, attenuation, return loss and other related parameters.
2. Cable structure and water ingress
People often mistakenly believe that the PVC material covering the standard data cable is waterproof. In fact, PVC material is hygroscopic. The standard Category 5 and Category 6 cables all use PVC jackets, which are designed for indoor use and are not suitable for use in humid environments. For outdoor environment with any amount of fog or water, waterproof measures will be taken for the designed cable, such as waterproof tape and gel filling, but these methods are costly and sometimes reduce the electrical performance. It is also worth mentioning that these waterproof gels are based on petroleum, so they are not suitable for indoor use (except for connection points), because they have fire hazards. In fact, the distance that these cables can be laid in the building is usually limited by national standards. In addition, the structure of the cable will also affect water ingress. Low smoke zero halogen (LSOH) cable generally has a low resistance to water ingress, because the moisture absorption capacity of the sheath material used is higher than that of PVC. The FTP cable with longitudinal foil shielding has a better ability to prevent water ingress, because the shielding material is similar to the water blocking tape. However, it should be noted that FTP is still not "waterproof".
3. Water ingress in structured cabling system
The impact of water inflow also depends on the source of water and the time of water inflow. The middle of the PVC cable laid is exposed to a small amount of clean water in a short term, which is unlikely to have any long-term harmful effects. However, if the low smoke zero halogen cable directly laid on the concrete floor does not use any pipes or protective measures, as long as it is submerged for a week, the risk of loss will be much greater. Water from dusty concrete floors and water containing dissolved pollutants also poses a greater risk.
In addition to being affected by water ingress through the cable sheath, the beginning of cable immersion in water will pose a much greater threat. The tight twisted pair inside the data cable will promote capillary reaction, which may suck water far away into the cable and damage the electrical characteristics of the cable. Almost all cables affected in this way must be replaced.
It is better to prevent in advance than to repair and replace the damped wiring system in the later stage, which is time-consuming, costly and destructive. Obviously, the best way is to prevent cable moisture. In an ideal situation, enterprises located in highly dangerous areas should consider the risk of moisture in the network design phase, and even for the existing cabling network, what measures can be taken should also be considered. If possible, cables should be suspended in ducts in ceiling spaces. This reduces the risk of moisture than wiring under the floor. By using pipes, such as cable racks, the cables can be dried faster when they are damp, while sealing pipes can better prevent a small amount of water from being immersed.
If the cable must pass through the floor space, the cable reel or cable rack shall be as high as possible above the floor plane within the allowable height of the raised floor.
As the loss caused by small floods such as water pipe burst is no less than that caused by large river flooding, it is better to keep the water pipe facilities away from areas where cables are concentrated, such as telecommunications rooms and/or equipment rooms. Do not allow water pipes to pass through these communication spaces, nor set up kitchens or toilets nearby. Do not set the telecommunication room or equipment room in the basement, especially when it is near the river! If isolation is not possible, consider using racks or cabinets, or building embankments to channel flooding to less affected areas.
conclusion
When the cable is wet, the required measures depend on the number of cables affected, the comparison between the replacement cost and the business loss risk of not replacing the cable, etc. For the cable with water entering through the beginning of the cable through capillary reaction, the cable should always be replaced. Cables that have been severely affected by water ingress through the skin may also need to be replaced. The network should be thoroughly tested and advice should be sought from the manufacturer or trusted installer. If there is no doubt, the cable should be replaced.
