What does a voltage reading of 120 volts from a top to a bottom jaw in a meter socket with the main disconnect open indicate?

A voltage reading of 120 volts from a top to a bottom jaw in a meter socket with the main disconnect open indicates that there is a potential issue with the electrical system. Since the main disconnect is open, the presence of 120 volts suggests that there is voltage present on the customer’s side of the meter, which is typically a sign of a ground fault.

In this situation, the reading indicates that there could be a ground fault, meaning that the electrical potential may be unintentionally reaching the ground due to a breakdown in insulation or some other fault in the wiring. Without the disconnect closed, any reading that shows voltage in this manner can reflect a risk since it implies that there is voltage still present on the load side of the meter despite the disconnect being open.

Understanding this scenario is critical for safety and troubleshooting in electrical systems. Thus, having a reading in such a situation raises concern rather than indicating that the system is functioning properly or that there's excessive current flow or a short circuit.