A protective insert for wires in a junction box is formed by a lockable cover having a frame with an opening and a pivotable cover for covering the opening. The frame is sized to rest on an inner lip of the box, which lip normally holds a lid for the box. The lid rests on the lockable cover. The cover may be pivoted open for access to wires in the junction box and may be pivoted closed, and locked, to protect the wires from theft or vandalism. The lockable cover is held down on the lip preferably by chains fixed to the frame with stakes fixed to a free end of the chains, and by pounding the stakes into the ground at the bottom of the box. In another embodiment, there is a lock. Further, the insert is anchored to the box by J-shaped hooks. In a further embodiment, the insert is anchored by an elongated rod with curled up ends, and may be set in concrete around the box.