Duplex surge arrestors

Claim 1

A duplex surge arrestor comprising: first and second electrically insulative housing; first and second solid conductive line electrodes having respective similar predetermined first and second discharge surface configurations, said electrodes sealed to respective ends of said first and second housings to position said discharge surfaces in longitudinal axial spaced relationship within said first and second housings; an earth electrode assembly sealed between confronting ends of said first and second housing to form a unitary, axially aligned, hermetically sealed enclosure containing a gas of selected ionization potential, said earth electrode having a central, solid electrode portion with third and fourth discharge surfaces at opposite ends thereof, said third and fourth discharge surfaces being similar to said first and second discharge surfaces and disposed within said first and second housings such that said first and third discharge surfaces precisely define a predetermined first discharge gap and second and fourth discharge surfaces precisely define a predetermined second discharge gap, said first and second discharge gaps each adapted to break down and fuse together their respective discharge surfaces when subjected to a high surge overload voltage; and gas communication means through the periphery of said earth electrode assembly between the electrode portion of said earth electrode assembly and the facing surface of said first and second housings and providing gas communication between said first and second housings such that when one of the line electrodes is subjected to a high overload voltage, gas within the respective housing is ionized and conveyed to the other housing to substantially reduce the breakdown potential of the remaining discharge gap.