Isolation vs Surge Suppression for Serial Communications

Serial data communications lines can carry damaging electrical transients caused by anything from ground loops to lightning strikes. So where do you deploy isolation, and where do you use surge suppression?

A surge suppressor directs high voltage transients safely to ground. Examples would include the power surges created by lightning strikes. But if the ground line rises, as it does in ground loop situations, you need isolation. Isolators stop transients by converting data signals to either pulses of light or an electrical field, then back again. Data passes through; transients don’t. But a sufficiently powerful transient can damage the isolator.

So you’ll probably find yourself using both approaches. Where you deploy surge suppression and where you deploy isolation will be a function of the specific application.