“The piece is really about danger,” Ms. Webster warned impishly. “Everyone knows you shouldn’t mix electricity with water.”

Three years ago the couple mentioned to Mark Fletcher, an art adviser who has long championed their work and is a board member of the Art Production Fund, that they wanted to do a project at Rockefeller Center. What they first had in mind was a giant three-dimensional version of “Toxic Schizophrenia,” a 1997 work of theirs consisting of a giant red illuminated heart dripping blood, with a jeweled dagger plunged into its center.

Rockefeller Center rejected the proposal. “New York wasn’t ready for blood after 9/11,” Ms. Webster explained. “We were really disappointed.”

So the couple shifted to more comfortable territory: a fountain.

In 1996 they created a two-dimensional fountain that was essentially a light sculpture. Ms. Webster said she and Mr. Noble had been obsessed with lights since their art school days in Nottingham and visited the fairgrounds by night. “The fair came to town once a year during the dull winter months, and all the students would hang out there,” she said. “We became especially fascinated with the light bulbs that were used, ones that would chase each other in a sequential line.”

Some Gypsies who worked at the fair told the couple where they could purchase such lights, and Mr. Noble and Ms. Webster began incorporating them in their art.

On visits to New York the couple were also captivated by the 60-foot-high red neon Pepsi Cola sign whose curlicues have floated over Long Island City, Queens, for more than 60 years.

Once their proposal for a giant fountain was approved, the couple began reading up on the art and architecture of Rockefeller Center. “In the foyer of Radio City there is this amazing mural that depicts the fountain of youth, so fountains are in its bones,” Mr. Noble said. “The Art of Rockefeller Center,” a 2005 book by Christine Roussel, convinced them they had hit on the perfect form, he added, quoting from one passage: “The Rockefellers knew the future would concentrate on the electric arts of sound and light.”

Just as tourists throw money into the Trevi Fountain in the hope that they will fulfill the age-old legend and return to Rome one day, Ms. Webster said she wants people to throw money into the “Electric Fountain.” “So many people have been sending us text messages,” she said. “Telling us they want to come to New York to bathe in the ‘Electric Fountain’ of love.”