Tesla coils have always played a special role in denoting the "mad" scientist. Created by that great icon of mad science himself, Nikola Tesla, the coils have long been beloved by high-voltage hobbyists. The world's largest existing Tesla coil, however, was commissioned neither as a work of science nor as a movie prop, but as a work of art.
Known as Electrum, this four-story (38-foot) Tesla coil was commissioned by a prominent New Zealand art patron, Alan Gibbs, and set up on on his farm outside of Auckland in April of 1998. Built by the late artist Eric Orr and high-voltage engineer Greg Leyh, the enormous coil puts out over 3 million volts, enough to rip electrons out of the air molecules around it.
A particular delight of Electrum is the hollow spherical cage on top of it, where Greg Leyh often sits during discharge shows. The arcs from the coil would instantly kill anyone they struck, but Leyh is safe within the Faraday cage created by the sphere. Of course, if he were to put his hand through the cage, he would be instantly electrocuted.
Though Electrum is the largest coil currently in existence, it is not the biggest ever created. That title belongs to an 18-story coil built in 1903 by Nikola Tesla himself at Wardenclyffe on Long Island. Unfortunately, it was torn down due to lack of funding before it was ever fully operational. But Leyh, the co-creator of Electrum, has plans to resurrect Tesla's dream of a giant coil — times two.
Under the project name "Lightning on Demand," or LOD, Leyh has purchased 81 acres in the Nevada desert where he plans to build twin 118-foot-tall Tesla coils, which would be big enough to generate 10-million-volt lightning arcs that would stretch across an area the size of a football field. Having built a pair of 1:12 scale (still almost 10 feet tall) coils as a proof of concept, Leyh is waiting for funding to help bring his electrical dream to life.
Other large Tesla coils currently in action include the "BIGGG" Tesla coil in Oklahoma, Big Bruiser in Wisconsin, and a pair of coils known as CAUAC that make an appearance at the annual Coachella music festival. A number of large coils can also been seen at the yearly Teslathon gatherings.