Cable splicing technology

Even the best built structured cable systems (SCS) are not insured against mechanical damage, including a complete break. In addition, even at the stage of building or upgrading the ACS, it is often necessary to create a reliable connection of cables in places that cannot be reached or are difficult to access after completion of the work.
In this small article, we, Maltima Telecom specialists , would like to talk about the basic principles of restoring cable integrity of the CCI (telephony) using the example of the 3M company which has been known for more than 40 years as a one-piece splicing technology that does not require the use of special cable couplings.

Thanks to the use of 3M technology or similar, when cutting a cable, stripping of the core insulation is not required. They are spliced ​​using modular or individual Scotchlok connectors with a piercing U-shaped contact. Due to their design, these connectors provide easy installation, reliable electrical contact and, if necessary, protection of the connection from moisture. For use in aggressive environments, some models of connectors are filled with a hydrophobic gel that prevents the ingress of water.
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UY2 adhesive tape connector



Scotchlok UY2 Crimping Tool

The procedure for splicing the core using the connectors is simple - it is enough to insert the ends of the wire together with the insulation into the holes of the connector, and then crimp the connector. Crimping is recommended to be carried out with the use of a special tool - press-ticks, which prevent over-compression of “scotch-tape”.

The next step in splicing the cable is to install a shield wire. Its task is to restore the electrical integrity of the cable shielding, if present. To solve this problem, 3M offers to use a screen connector, for example Scotchlok 4460-D, and a grounding tape. After completing the splicing of the cores and the restoration of the shield, the cable should be checked for electrical integrity.


Removable sealing compound 8882-E


Vinyl tape EZ 2183

Making sure that the electrical integrity of the cable is restored, you can proceed to the conclusion of the splicing site in the plastic formwork and filling it with an insulating hydrophobic compound. In the role of a compound, 3M suggests using a two-component sealing gel that easily penetrates to the joints even at low temperatures, due to its low viscosity and long curing time (96 minutes). When using a sealing gel, follow the manufacturer's instructions.

The last step in splicing the cable is to restore its protective sheath. The first stage of this process is the creation of an internal overpressure at the site of fusion by winding vinyl tape, for example, 3M EZ 2183. After that, it is fixed and sealed using 3M VM vinyl mastic tape. It, in turn, must be covered with a layer of general-purpose electrical tape. Finally, the final step in restoring the cable protection sheath is wrapping the splicing site with a bandage. In its role can be a structural material 3M Armorcast , which is a mesh tape made of fiberglass cloth, impregnated with a special composition, hardening under the influence of moisture (24 hours).

So, we have just seen that splicing a multicore cable is not a big deal for trained personnel. The whole process can be divided into eight main stages, controlling each of them: 1. Splicing the wires with U-shaped connectors; 2. Screen recovery; 3. Verification of electrical integrity; 4. Fabrication of formwork and pouring of a hydrophobic compound; 5. Winding vinyl tape to create excessive internal pressure; 6. Sealing joints with vinyl mastic tape; 7. Covering the splicing place with tape; 8. Reinforcement of the splicing site with a special structural material.



Note that the time required to perform all stages of the operation depends not only on the qualifications of the performers, but also on the fixation speed of the compound and the reinforcing structural material. To calculate the duration of the process, we recommend that you rely on the recommendations of the manufacturer of the materials used.

Important note: the above-described technology is not suitable for splicing cables for transmitting digital signals in horizontal cable systems, since it explicitly prohibits GOST R 53246-2008. In this case, the cable must be continuous, so that if it is damaged, the entire “string” changes completely.