What is a reason for using -48VDC with a positive ground in the telecommunications industry?

Using -48VDC with a positive ground in the telecommunications industry is primarily aimed at mitigating electrolyte corrosion on the outside plant infrastructure. This voltage configuration helps to create a protective environment for the metallic parts of the telecommunications systems, especially in scenarios involving wet or humid conditions where corrosion could be a concern. By using a negative voltage relative to the ground, it decreases the likelihood of galvanic corrosion, which can occur when dissimilar metals are present and current passes through the soil or water, leading to deterioration of those metals.

The choice of -48VDC is commonly adopted because it not only helps in corrosion prevention but also improves safety concerning human exposure to electrical elements, as the system maintains a lower potential than the ground. This voltage specification is a standard in many telecommunications facilities as it provides an effective balance of safety, reliability, and performance of the equipment involved in telecommunication installations.