A highly efficient line transient protection circuit is provided for high power loads that are designed to operate through a high line transient. The transient protection circuit for high power loads is provided with a primary leg circuit, a load circuit and a secondary circuit. The load circuit may be a switching regulator circuit, a load circuit containing an oscillator, a push-pull circuit, a boost converter circuit, a buck converter circuit or the like. The transient protection circuit is provided with a simple driver circuit to turn on a bypass n-channel MOSFET. It operates at a higher efficiency; I.E., conduction losses are minimized during normal input voltage conditions. Furthermore, the transient protection circuit provides a programmable voltage clamp which is implemented through selecting zener diode VR1. The transient protection may be used to protect medium to large current circuits from line transients. Additionally, the transient protection circuit it is suitable for applications in loads that have to operate through a high line transient (e.g. military, medical, etc.).