What are the two types of underground cable?

The classification of underground cables into shielded and non-shielded categories is significant in terms of electrical performance and safety. Shielded cables are designed with an extra layer (shield) which protects the conductors from external electromagnetic interference and helps contain the electric field generated by the cable itself. This shielding is particularly important in environments where cables are subjected to various electromagnetic threats, like in substations or industrial areas. It enhances the cable's performance and reliability, reducing the risk of electrical noise that can affect communications and data signals.

On the other hand, non-shielded cables do not have this protective layer. They are simpler and cost-effective solutions for applications where the risk of interference is minimal, such as residential wiring or where distance from any interference sources can be guaranteed.

While insulated and non-insulated cables are also important classifications regarding their ability to prevent current from leaking or contacting surrounding materials, they do not fully address the concerns about external interference and the cable's operational environment. The single-core and multi-core classification focuses more on the number of conductors within the cable rather than their ability to withstand external electromagnetic effects.

Thus, understanding the distinction between shielded and non-shielded cables is crucial for apprentices in ensuring they select the appropriate type for their specific