An insulator for an electric fence, an electric fence system using the insulator, and a method of installing same are disclosed herein. The insulator includes a body having a first end and a second end, and a wire attachment portion positioned at the first end of the body. A passage passes through the wire attachment portion, the passage including a first open end, a second open end, and a waist region between the first open end and the second open end. The diameter of the passage at the first open end and the diameter of the second open end are both greater than at the waist region.