Main lug indoor load center, 100 A, 6 space/12 circuit. 1-1/2 in knockouts in the top and bottom end walls to allow for use with either overhead or underground fed electrical wiring. 22,000 short circuit current rating (SCCR) and can be fitted with a secondary surge arrestor (not included) for added protection. Single phase, 3-wire, solid neutral. UL listed.