The 420E series is a two stage transient voltage protector providing primary and secondary protection against lightning, inductive switching and electrostatic discharge (ESD) transient threats. The first stage diverts the transient current through the ground terminal return path and the second stage clamps the voltage to a safe level without interruption of service. The 420E series is designed to protect 4-20mA analog control loops from differential (line to line) and common mode (line to ground) transients. Terminals 1 and 2 are designated as line pairs for both the line and the equipment side of the protector. A transient voltage suppressor is internally connected across each line pair for differential mode protection. Each line pair is referenced to ground. This product can also be used on telephone, signal/data lines, security, timing and control interface circuits.