Grounding, or connecting some part of an electrical circuit to ground ensures safety for personnel and it usually improves circuit operation. Unfortunately, a safe environment and a robust ground system often do not happen simultaneously. It takes planning based on systematically understanding how electricity behaves in various types of circuits. Preventing electrical shocks and electrical fires is the highest priority for ground circuits (high redundancy is one key feature), but the redundancies built into many electrical grounding systems occasionally limit certain kinds of connections for input to data acquisition systems.
Noise Reduction and Isolation white paper tells that controlling noise in measurement systems is vital because it can become a serious problem even in the best instruments and data acquisition hardware. Most laboratories and industrial environments contain abundant electrical-noise sources, including AC power lines, heavy machinery, radio and TV stations, and a variety of electronic equipment.