An electrical enclosure includes a main cabinet and a modular cabinet removably secured to the main cabinet. The main cabinet includes a bus compartment that includes a busbar assembly, and the bus compartment is located between an end wall of the main cabinet and a partition opposite the end wall. The modular cabinet is comprised of interlocking compartment modules. Each compartment module interlocks with an adjacent compartment module. Each compartment module includes first and second side panels. Each side panel includes an alignment member that engages an alignment member of a respective side panel of the adjacent compartment module. Each compartment module also includes a base that extends between the first and second side panels and a terminal wall that joins the first and second side panels. The terminal walls of the interlocking compartment modules engage to form a structural wall of the modular cabinet.