Throwing my hands up on this ignition!

[QUOTE="Dave_J, post: 1973582620, member: 57782"..
In telephone Central Offices they use 48 volts DC for everything inside except lights and test gear. The lines on the street uses that 48 Volts @ 600 Miliamps up to 30,000 feet at times so you have dial tone at the house/shop. When they go over 30,000 feet, somewhere near the center they add what is called a 'Load Pot' that has lots of load coils in it. When they put these load coils in, they up the line voltage to 54 Volts DC and the load coil boosts the output amperage up some. You may have 54 VDC incoming and 48-52 VDC outgoing....[/QUOTE]
Ill gently add to this, the CO uses -48V DC (strange but that is what it is) even for certain test gear. Try finding an external power supply for that unicorn!