To better support distribution systems commonly found outside the US, Revit supports single phase two-wire line-to-neutral panelboards.
Prior to this enhancement, Revit supported panelboards configured as three phase (3 pole, 3 hot conductors, with or without neutral), and single phase (2 pole, 2 hot conductors, line-to-line, with neutral). When using single phase panels (1 pole, 1 hot conductor, line-to-neutral), there were some undesirable results.
With this enhancement, Revit now properly supports single phase (1 pole, 1 hot conductor, line-to-neutral) panelboards.
This enhancement was suggested by customers on the Ideas forum (1, 2, 3, 4) and is described on the product road map.