Which signal condition requires a stop at the home signal?

The condition that necessitates a stop at the home signal is a stop signal. A stop signal is specifically designed to instruct train operators that they must halt their train before proceeding any further. This signal indicates that the track ahead may not be clear or safe for movement, requiring the operator to stop and assess the situation before taking any further action.

In contrast, a proceeding signal and a clear signal indicate that it is safe to continue operating, while a warning signal offers a preliminary notice that the next signal may require a stop. Hence, only the stop signal explicitly requires a train operator to take immediate action to halt the train, highlighting its critical importance in ensuring safe operations on the rail system.