I hear that, we use -48vdc in our telecom equipment, that wouldn't be bad if all we had to do was put black wire to positive but nooooo, if we install equipment in a substation and we don't have our own DC plant we have to wire black, negative ground because that's how the substations crews do it. On top of that we have some equipment that while is 48 volt equipment it's wire colors are reversed from most or all other Telecom equipment (Bayly channel banks- Canadian). What do I do? Multimeter and I check even if I think I know, can't let the smoke out on the equipment, it's very expensive!