©Sealevel Systems, Inc.
SL9049 - 06/2011
SeaI/O Manual
102
A ground-referenced signal is a signal that is connected in some fashion to the building system
ground and therefore is already connected to a common ground point with respect to the
SeaI/O-570. Examples would be non-isolated outputs of instruments and devices that are
connected to the same building power system as the SeaI/O-570. The difference in ground
potential between two devices connected to the same building power system is typically 1mV to
100mV and can be much higher with improper power system grounding. This ground potential
difference can show up as a measurement error without using the proper measurement
connections. The above connection scheme is designed to eliminate this ground potential
difference from the measurement.