Questions and answers about common shielded wiring systems such as lightning protection, grounding, and safety (1)

Q: Is it dangerous to use a shielding system?
Answer: No. If a TN-S system is used, the system is as safe as an unshielded twisted pair system. Poor grounding or poor power distribution systems can affect various copper cabling systems. If using TNC or TN-C system. A current will appear on the PE (N) line. If it is a shielding system, current will appear on the shielding layer and the reference potential. If an unshielded twisted pair system is used, current will appear at the reference potential.
When a lightning strike occurs, the risk of damage to the shielded system is lower than that of the unshielded twisted pair system.
Q: I have a TN-C or TN-C-S system, how do I use a wiring system?
Answer: First measure the current on the PE in the switch system. If the potential difference exceeds 1V, an equipotential line should be installed between the exchange points. A more effective method is to change the switch system. In both cases, the PEN line can cause many problems.
Q: Should the shields be connected at one end or the shields at each other?
Answer: It should always be connected at both ends (ie, on the distribution frame and network equipment, not on the socket), the brake effectively suppresses all electromagnetic compatibility mechanisms and avoids antenna effects.
Q: Is it necessary to use metal separation in the cable duct of the shielding system?
Answer: It is only needed when the length of the pipeline is greater than 35 meters. For unshielded twisted pair systems, metal partitions must always be used.
Q: Is it enough to use an FTP cable? Is it better to use a PiMF cable?
Answer: From the perspective of electromagnetic compatibility and performance, PiMF cable is the best solution.
Q: Does lightning strike also affect unshielded twisted pair systems?
If there is no lightning protection system, the magnetic flux will be very strong, so that the pair in the unshielded twisted pair cable cannot suppress the signal. With shielded system partitions, lightning near the structure is 10,000 times more likely to cause internal system failure. This is explained in IEC62305-2 / FDIS.
Q: Can the unshielded twisted pair system meet the electromagnetic compatibility requirements?
Answer, it is possible. Today there is no standard for the electromagnetic compatibility of wiring systems. Therefore, from a system perspective, there are no restrictions that must be met. The EMC directive only requires the owner to be responsible for not interfering with other systems and without interference from other systems. Some tests have shown that unshielded twisted pair systems cannot meet the requirements of EN 55022B. The standard targets residential and office environments.
Q: I have an unshielded twisted pair system. Do I need a grounding system?
Answer: Yes. Grounding is for safety. All electrical installations with a voltage exceeding 25V AC, 60VDC or within SELV must be grounded. Even for fiber optic facilities, a well-designed, fully functional grounding system is also necessary.
Q: I have an unshielded twisted pair system. Do I need an equipotential bonding system?
Answer: Yes. Equipotential bonding is for safety. All electrical installations must have equipotential bonding. In addition, it can improve the electromagnetic compatibility performance. This applies to various wiring systems.
Q: My system supplier provides electromagnetic compatibility guarantee / conformity guarantee for my wiring system. Does this mean that I have summed up my responsibilities?
Answer: No. If the system is active, there is no clear meaning yet.

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May. 04, 2020