The 420E2 series of protection 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 420E2 series is designed to protect 4-20mA analog control loops from differential and common mode transients. Terminals 1 and 2 are designed as the line pairs for both the line and 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.