Abstract: A modular toroidal transformer core cap system, including a plurality of cap segments, wherein each respective cap segment further includes first and second spaced elongated wall members, first and second connector members connected to the respective first and second elongated wall members, and a generally flat panel member connected to and extending between the first and second elongated wall members. The first and second wall members are disposed at a predetermined angle relative one another and the first and second elongated wall members and the panel member are electrically nonconducting. An integral number of cap segments may be joined together to define an annular core cap.