Maintaining communications and power during transfer of horizontally moveable elevator cab

A socket plug assembly (44) on an elevator cab (10) may engage with complimentary socket plug assemblies (46) on either of two car frames (11, 13) when it is horizontally moved therebetween. A socket plug assembly (44a) on a horizontally moveable elevator cab may have a horizontal interface with a complimentary socket plug assembly (45b) mounted on an elevator car frame or landing, and one of them is moved vertically to cause engagement with the other. Socket plug assemblies (169) tethered to a cab (10) by means of an umbilical cord (168) is engageable with socket plug assemblies (170, 171) on booms (172, 173) on the elevator car frames (21, 22) or landings. An uninterruptible power supply (50) maintains power when the cab is unplugged; a transceiver (51) on the cab maintains communications with a transceiver (62) in the building when the cab is unplugged.