Common sense says that connecting wires such that resistance of the wiring is additive (in series) in a return path for one device, but not others, creates a different voltage at “ground” for that one device (V=IR).Ī chassis ground is a ground-collection point that connects to the metal enclosure of an electrical device. Wires and traces have resistance in the real world and do affect how a return path (“ground”) plays out for return rails, for instance. ![]() Current flow (I) through any material with resistance (R) will have a voltage (V) other than zero. ![]() This is most likely if the circuit or device happens to operate with high amperage draws, or in cases where the ground plane, conductor, or rail has a high impedance (i.e., the “grounding” material or “ground conductor/rail” is not a good conductor of electricity.) Ohm’s law is in effect, regardless: V=IR. The unusual cases are where issues develop because the “zero” voltage of ground isn’t near zero at all. In reality, a ground plane or rail will usually have varying voltages at negligible levels. Source: Wikipedia.īut ground as zero voltage is theoretical only a conductor with zero impedance will have zero voltage. ![]() Figure 1: There are three different electrical symbols for ground, indicating context within a schematic. All three indicate connecting to a point of (theoretically) zero voltage, but within a different context: chassis ground for a device, signal ground for very low voltage signals within a device, and earth ground for a power system. In analog design, the relationship of a signal to ground is of fundamental concern (and can create issues in digital designs, too.) However, “ground” as a concept can be confusing as it relates to three different situations: chassis ground, signal ground, or earth ground.
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