Power distribution unit and methods of making and use including modular construction and assemblies

A power distribution unit vertically mountable in an electronic equipment rack and configured to distribute power to equipment in the rack, comprising:

• a housing including an interior cavity;
• and
• a plurality of coupled modules removably secured to the housing at least partially within the interior cavity, comprising at least one outlet module, at least one power input module, and one or more of a circuit protection module, a communications I/O module, and a display module;
• each of said modules comprising a first end having a connection element of a first type and a second end having a connection element of a second type mateable with connection elements of the first type;
• said modules being removably secured to each other via mateable engagement between connection elements of the first type and connection elements of the second type in a first end to second end configuration.