Certificates of deposit, or CDs, are fixed income investments that generally pay a set rate of interest over a fixed time period.
When referenced to the local common or ground, a common-mode signal appears on both lines of a two-wire cable, in-phase and with equal amplitudes. Technically, a common-mode voltage is one-half the vector sum of the voltages from each conductor of a balanced circuit to local ground or common.
Common Mode Noise is found in the actual power cables, not in the data cables connected devices. UPS's filter out and protect you from Common Mode Noise, but they can not protect you against Inter-system Ground Noise. It is possible to have Inter-system Ground Noise and no Common Mode Noise.