What is the standard voltage for most railway signal systems?

The standard voltage for most railway signal systems is typically 12 or 24 volts DC. This lower voltage range is preferred for signal systems due to safety considerations and the proximity of personnel to the equipment. Lower voltage systems help reduce the risk of electrical shock while still providing adequate power for the operation of lights and signals on the railway.

Additionally, many railway communication systems and electronics operate effectively within this voltage range, benefiting from the simplicity and reliability of direct current (DC) for their operations. Using 12 or 24 volts allows for longer runs of wiring without significant power loss and reduces the need for more complex high-voltage insulation and protective measures that would be necessary at higher voltages.

In contrast, the other voltage options listed, such as 120 volts AC and 240 volts AC, are generally used for industrial or household electrical systems but are not standard for the safety-focused and operational needs of railway signaling. The 48 volts DC option, while used in some specific applications, is less common compared to the 12 or 24 volts DC standard for railway signal systems.