What would a meter indicate in volts between points A and B with the SBJ installed in the panel?

The indication of 0 volts between points A and B suggests that there is no potential difference, which means that both points are at the same electrical potential. This can occur if the circuit is de-energized or if the SBJ (Service Disconnect, usually a circuit breaker or switch) is open, effectively isolating the load from the electrical source. In this scenario, since the SBJ is installed in the panel and is likely tripped or open, there is no voltage supplied to the circuit, resulting in an output of 0 volts when measured between the two points.

This situation is common in safety measures where an electrical circuit is de-energized to prevent any accidental shock or short circuit. The presence of the SBJ indicates that the circuit should be treated as non-live when the breaker is in an off or open position.