Motor vibrations are tested as a part of factory acceptance testing (FAT), normally on a massive foundation. In two-pole motors, there are two main sources of vibration: rotor unbalance and electrical twice-line frequency excitation. Low vibration implies that the natural frequencies of the motor are separated from the corresponding excitation frequencies. Usually, if the site foundation is rigid, the vibration levels repeat FAT values with minor changes and are well within the initial limits for condition monitoring. However, if the foundation is flexible, the motor vibration may produce unexpected results. The aim of this article is to introduce a procedure to help ensure low vibration in site conditions in these cases. The procedure relies on early cooperation between the motor manufacturer and the system integrator based on the horizontal and vertical stiffness of the foundation. The most cost-effective solution can be reached by incorporating proper motor design features in conjunction with the design of the mounting base.