It's a matter of perspective. You tie one of the leads to earth (literally grounding it)[1], leaving the other non-grounded. Depending on if you tie the negati

It's a matter of perspective. You tie one of the leads to earth (literally grounding it)[1], leaving the other non-grounded. Depending on if you tie the negative or the positive lead to ground, you get 48V or -48V with respect to ground. As long as the potential between the most positive lead and the least positive lead is 48V, the circuit itself doesn't care. As mentioned here[2], the reason for grounding the positive lead is to prevent galvanic corrosion[3] destroying the buried copper. [1]: https://www.bicsi.org/docs/default-source/conference-presentations/2017-mea-uae/grounding-and-bonding.pdf https://www.bicsi.org/docs/default-source/conference-present... [2]: https://www.poweringthenetwork.com/uncategorized/negative-48-volt-power-what-why-and-how/ https://www.poweringthenetwork.com/uncategorized/negative-48... [3]: https://en.wikipedia.org/wiki/Galvanic_corrosion https://en.wikipedia.org/wiki/Galvanic_corrosion