In a telephone switching station, which voltage is MOST likely to be available at the facility?

In a telephone switching station, the voltage that is most commonly available is -48VDC. This standard is widely used in telecommunications for powering various equipment, including telephone switches, routers, and other data transmission devices.

The negative voltage is preferred in such environments primarily due to its safety and corrosion prevention qualities. Using -48VDC reduces the risk of electric shock, making it safer for maintenance personnel working within the facility. Additionally, a negative DC voltage helps to mitigate the risk of electrolysis which can lead to equipment corrosion.

While other voltages such as 120VDC, 220VAC, and 440VAC may be found in some facilities, they do not match the industry standard practices for telephone switching stations where the electrical systems are designed to operate efficiently and safely at -48VDC. This makes -48VDC the most appropriate and expected voltage in this specific context.