This paper investigates the effect of voltage stress on the voltage insulation components inside a regenerative active-front-end adjustable speed drive (ASD). It shows that a high potential voltage insulation issue may exist on various components inside the ASD and cause earlier failures. A simplified system model to describe this phenomenon is described, and the voltage stresses of different components inside the ASD under different grounded conditions are analyzed. It is concluded that a much higher voltage stress may exist in different locations of the drive under different grounding systems. Appropriately designing the insulation components is critical to protect the drive.