The invention provides an electricity distribution system, which can keep a voltage to ground low, and can commonly detect abnormity, such as an electrical leak etc. produced in AC and DC feed lines. An AC-DC converter 21 is installed between the AC feed line (branch electrical circuit Lb) of a single phase three wire system for supplying the power to AC devices 41, and the DC feed line (main electrical circuit Ld) of a three wire system for supplying the power to DC devices. The DC feed line comprises a neutral wire N commonly connected to a neutral wire N of the AC feed line within the AC-DC converter 21, a positive voltage wire L+ having a positive electrical potential to an electrical potential of its neutral wire N, and a negative voltage wire L− having a negative electrical potential to the electrical potential of its neutral wire N. A voltage of +150 [V] is applied to the positive voltage wire L+, and a voltage of −150 [V] is applied to the negative voltage wire L−.