When you are drawing in isometric mode, you add schematic lines on one of the 3 isometric planes: left, top, or right. Each isometric plane has an associated pair of axes. Choosing an isometric plane causes the AutoCAD® Ortho mode and the crosshairs to be aligned along the corresponding isometric axes in the world coordinate system (WCS). Working in isometric mode is beneficial, for example, when creating electrical riser diagrams.
As you draw, you can switch between planes by selecting a different value for Isoplane on the Properties palette. Switching between planes enables you to draw a continuous isometric run, where segments are drafted both horizontally and vertically along the different isoplanes. For example, you might draw one segment on the top plane, switch to the left plane to draw a riser, and then switch to the right plane to complete the run.
Drawing a schematic line on the left isoplane
Drawing a schematic line on the top isometric plane
Drawing a schematic line on the right isometric plane