Transformers, coupling capacitors, optocouplers—and now, iCouplers—are typical means of providing galvanic isolation, which blocks current from flowing between two points, while allowing data to pass unimpeded (Figure 1). Isolation is used to protect against high voltages or currents caused by line surges or ground loops, which can occur in any system that has multiple ground paths. System grounds that are separated by long cables will not be at the same potential, so ground current will flow between the two systems. Without isolation, this current could introduce noise, degrade measurements, or even destroy system components.