The selection of shielded and unshielded cables depends on the external electromagnetic interference. When the interference field is lower than 3V/m, no protective measures are considered. When the interference signal exceeds the standard amount, shielded cables can be selected. The price of a shielded cable is 1.2 to 1.6 times that of an unshielded cable. Therefore, shielded cables are suitable for areas with severe electromagnetic interference and places with high confidentiality requirements.

In THE MEANTIME, WIRING SYSTEM SHOULD CONSIDER CURRENT DEMAND ALREADY, SHOULD give PROPER CONSIDERATION TO FUTURE DEVELOPMENT AGAIN, ALSO CANNOT IGNORE THE INFLUENCE OF EXTERNAL FACTOR. Just like the foundation of a building, the basic role of the wiring system in the intelligent system determines that it is impossible to change in a short period of time once it is built, so the wiring system has a long life cycle - that is, 15 to 25 years.

The main option for the current user

With the rapid development of technology today, if the development is not considered, it is likely that by the time the wiring system is completed, the product and performance will have fallen behind the needs of the users. That is not the choice of advanced products must be correct? That's not necessarily the case. Getting too far ahead not only increases investment, but also may be out of step with demand and waste resources. In addition, such as the performance of network products, access line bandwidth, office equipment and other external factors, also affect and restrict the performance of products to a large extent, without comprehensive consideration of environmental conditions and one-sided pursuit of product advancement, will fall into the mistake of product purchase. According to the above analysis of user needs and selection principles, the current users and their wiring product purchase schemes roughly have the following three kinds:

First, high-end users, who have high requirements on the processing and transmission speed of all kinds of information, attach great importance to the stability and security of products and systems, and have strong funds, represented by media, sports venues, transportation and hospitals. Its wiring system adopts six or higher systems, special needs also consider the use of optical fiber. For example, audio/video transmission in media buildings requires high frequency and field strength of information flow, and there are many radio interference sources. In order to avoid the interference between signals of transmission lines and electronic equipment, shielding and optical fiber wiring system are often used. For example, the wiring system of the competition venue should pay attention to three aspects:

· In outdoor venues, attention should be paid to moisture-proof, ash-proof, destruction-proof and lightning-proof devices;

· Considering the relatively large plane area of the stadium, multiple telecommunication rooms should be set up, and it is better to use optical cable communication between each telecommunication;

· Pay attention to the deterioration of technical parameters and performance indicators due to the aging of devices caused by outdoor environment.

Therefore, from the safety point of view, shielding and optical fiber wiring system are mostly used. Transportation buildings are characterized by a large building area. When it comes to the connectivity between buildings in different places, the decline of cables along the pipeline is reflected, which is an extended star network. The main part of the cable route is long, so the optical fiber routing system is recommended.

For problems involving electromagnetic interference of electromechanical equipment, the shielding of cables should also be considered. Hospital is the most important is the need to consider cable for transmission bandwidth and electromagnetic interference problem of medical equipment, due to large hospitals occupied area, buildings, more complex functional requirements, to put it into a multi-functional building group, in accordance with the requirements for wire cloth between building design, in order to meet the needs of many conditions, using shielded wire + fiber optic cabling system more appropriate.