If you hade a single phase load that worked with the available voltage coming off of the manufactured leg.
Imagine the 3 phase panel with every thid breaker not used because it was a manufactured leg. Somebody wants to add a single phase circuit that would only get used if the equipment using the phase converter is running. For instance task lighting or an external auxilary pump. This somebody measures the manufactured phase to earth voltage and decides that it is close enough to operate the device in question. So they drop in a breaker and away they go.
Notice I did not say that this someone was qualified to perform this installation, it is just someone who knows enough to be dangerous.
Larry C
