How many backstage employees does it take to change a lightbulb? No, this isn't a tasteless joke but a question posed by a recent comment to this blog. Searching for an answer, I sat down with Alex Mustelier, Lincoln Center Theater's facilities manager, Mike Assalone, LCT's associate facilities manager, and Ron Busch, chief engineer for the theater but employed by Lincoln Center for the Performing Arts.

"Making sure the place is in order," Mustelier said, succinctly, "is about a lot more than changing the lightbulbs in the lobby."

Assalone elaborated. "Routine facility maintenance," he said, "is taken care of by four porters in the building. Two of them work during the day, taking care of the dressing rooms, the lobby, the theater. They clean up, they change supplies, they wax the floors every Tuesday, so when the actors come back from their day off they return to something spic-and-span. And there's a performance porter, who picks up at intermission, making sure things are taken care of at show-time."

Air-conditioning, heating, and plumbing are the province of engineering. "Those systems are automated at Lincoln Center Theater," Busch explained, "and are usually a matter of 'set it and forget it.'" But adjustments occasionally must be made. Take South Pacific's famous shower scene. When performances began last March, Kelli O'Hara, who plays Nellie Forbush, discovered that when she got wet onstage she also got cold: always a concern for someone who has to sing eight shows a week.

So at every performance the engineering department now has a cue from stage management. "Somebody downstairs," Busch said, "is signaled to send 120-degree air onto the stage at that time. This doesn't last long, and certainly doesn't affect the comfort of the audience. The house's fan system is different than the stage's anyway -- the stage has two and the house one."

In addition to the shower-scene adjustment, Busch mentioned another engineering matter unique to South Pacific: a large live orchestra. "We have to make sure that they're kept cool," he said. "They're down below, working throughout the performance, so we need to pay attention."

Other maintenance matters may happen only once or twice a year. "Dressing rooms," Assalone said, "are painted between productions, and touched-up during long runs." Still other things may be weekly or monthly -- making sure the 100 fire extinguishers in the theater are functional, and that the six medical cabinets around the facility are steadily stocked. "And we have to be constantly on guard," Assalone added, "so that the defibrillators are in working order. A couple of months ago, one of them was used to save an audience member's life." And who operated it? "A flight attendant who happened to be seeing the show that day," Assalone said. "We do a lot, but occasionally a non-employee is allowed to pitch in."

BRENDAN LEMON is the American theater critic for the Financial Times and the editor of lemonwade.com