Why is -48 VDC with a positive ground commonly used in the telecommunications industry?

Using -48 VDC with a positive ground in the telecommunications industry is primarily a measure to mitigate electrolytic corrosion, which is crucial in maintaining the integrity of equipment and the overall system. This specific voltage and grounding configuration helps to reduce the potential for ion migration in metal connections, which can lead to corrosion over time.

In telecommunications, equipment often interfaces with various conductors and metal parts. By employing a negative voltage with a positive ground, the electrochemical reactions responsible for corrosion are limited, effectively increasing the longevity of the equipment and reducing maintenance costs. This is critical in an industry where reliability and longevity are paramount due to the expenses associated with downtime and repairs.

Other options, while related to electrical systems, do not align with the established practices or commonly understood benefits in telecommunications. Thus, the choice of -48 VDC with a positive ground is supported by the need to manage corrosion and protect the infrastructure.