Concealed installation of LiYCY cables

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In professional automation and data transmission systems, LiYCY shielded cables are widely used for transmitting control signals. A key issue for designers and installers is whether these cables can be installed directly under gypsum plaster. Below we analyze this issue based on chemical, mechanical, and regulatory criteria.

Chemical Stability of the PVC Sheath

The outer sheath of LiYCY cables is made of polyvinyl chloride (PVC), which shows full compatibility with gypsum plasters. Gypsum (calcium sulfate), once set, is chemically neutral, which eliminates the risk of polymer degradation or plasticizer migration.

However, the absence of chemical interaction does not necessarily guarantee physical safety of the cable when installed directly within this layer.

Shield Protection and Electromagnetic Compatibility (EMC)

The design of LiYCY cables requires special attention. These cables feature high-flexibility conductors (Class 5) and a shield made of braided copper wires, often without an additional internal protective layer.

Direct installation in plaster may expose these components to:

Mechanical stress:
Movement of the building structure may generate shear forces that, in extreme cases, could break the continuity of the shielding.

Loss of EMC performance:
Even localized damage to the braid reduces the cable’s ability to protect against electromagnetic interference, which is critical for the stability of data transmission systems.

Voltage Classification and Intended Use

LiYCY cables are designed as signal cables with an operating voltage of up to 300/500 V (depending on conductor cross-section). They should not be confused with low-voltage installation cables such as YDYp.

Using them in 230/400 V power supply circuits without considering their specific load capacity and intended purpose is inconsistent with engineering best practices.

Installation Recommendations

Direct installation is technically possible; however, we recommend installing flexible cables inside protective conduits (corrugated pipes). This solution provides:

effective mechanical protection for the copper braid shield
the possibility of non-invasive cable replacement in the future
additional protection against technological moisture during plastering works

Conclusions

From a chemical perspective, installing LiYCY cables under gypsum plaster is safe. However, it may pose a risk of degradation of transmission parameters due to potential mechanical stress.

To ensure maximum reliability of control systems, the use of protective conduits is recommended. This approach is consistent with the guidelines of PN-HD 60364-5-52.

Reviewing the full technical specification of the cable will help avoid installation errors during the implementation stage.