Cannon Street is a tinderbox, its rows of wooden houses positioned near the center of the more than 85 suspicious fires that have occurred on the peninsula since 2000. So when Scott Kay started remodeling a two-story house on the street, he looked at the historic structure he was about to improve and made the decision to install a fire sprinkler system.

He spent about $7,000 to have a plumber put sprinklers in the 3,500-square-foot duplex, which he is in the process of gutting and repairing for use as college student housing. At $2 per square foot, he sees it as a big up-front investment, but certainly a worthwhile one. According to the S.C. Master Plumbers Association, when a fire breaks out in a home without a sprinkler system, the average cost of the damages is about $45,000. In homes with a sprinkler system installed, the average damages are only $2,100.

“The parents have been thrilled,” Kay says. “We did it for insurance reasons and peace of mind. Most college kids, they don’t have any idea about it, but they’ll appreciate it when they have it, I think.”

Last July, a fire started in a house one block to the east of Kay’s. College of Charleston student Allison Hammons had only been living for a month in the downstairs half of the building at 54 Cannon St. when a fire broke out in the early morning, apparently beginning on the long side porch before spreading and scorching much of the building. She had heard about the string of suspicious fires when she moved in, particularly among houses occupied by students, and this one had come right up to her door.

“There are a lot of college students in this area, so you kind of just hope and pray that it won’t be you,” she said at the time.

Since many of the downtown fires have started on porches, Kay is taking an unusual extra step: installing sprinklers on the first- and second-floor front porches, as well as a side porch. Kay’s own parents had to rebuild their house on the Isle of Palms after it burned last January, and he learned from their experience that a sprinkler system was worth the cost.

The man who sold Kay his sprinklers is Charlie Stewart, who is perhaps the biggest advocate for sprinkler installation in Charleston. Stewart grew up in the plumbing and fire-prevention business, as his father was the fire chief at Westvaco’s North Charleston paper mill. When he stumbled upon a cheaper way of installing sprinklers in 2009, he saw an opportunity to baptize the city in the name of fire preparedness.

Stewart, of course, has a sound financial reason to pitch fire sprinklers downtown: He makes a living training plumbers to install sprinklers and selling them supplies through his company, Phoenix Distributing. But even outside of the plumbing business, sprinkler installation is considered a worthwhile investment. At the beginning of 2011, the International Code Council, a membership association concerned with fire prevention and energy efficiency, mandated that all new one- and two-family dwellings must include a sprinkler system. However, South Carolina is not bound by the ICC.

Neither the State of South Carolina nor the City of Charleston requires fire sprinklers in houses. But Tom Scholtens, Charleston’s chief building official, says a sprinkler system is a worthwhile investment, especially in residences. He says fire sprinklers are not common in the city’s historic district, as most of the buildings predate the systems’ widespread adoption. The cost is comparable to installing granite countertops or hardwood floors, and for new construction, he estimates that the impact on a homeowner’s mortgage payment is roughly equal to the price of a Big Mac every month.

In the past decade, sprinkler technology has changed radically. Previously, sprinkler lines had to be installed separately from regular tap water lines. It was an expensive proposition, often costing more than $10 per square foot, and water could stagnate in the pipes for decades if the system was never activated. As a result, sprinkler installation specialists had to outfit the sprinkler lines with pricey backflow preventers, and homeowners had to pay an inspector to check the system annually.

The new breed of sprinkler systems is head-smackingly simple by comparison, combining tap water and sprinkler lines into a single flow. At Kay’s house, a network of flexible tubes made of cross-linked polyethylene snakes its way from room to room in the ceiling, and it will supply water for everything from sinks to toilets to showers to sprinklers. An added advantage is that, because the water does not sit still in the pipes, annual tests are not necessary. “Every time you turn your kitchen water on, you’re testing the system,” Stewart says.

The sprinkler heads are activated by heat, not smoke, meaning that residents are not at risk of flooding the house when they burn popcorn in the microwave. The sprinklers work independently, with no electronic parts involved. At 135 degrees, a cosmetic plastic cover pops off, revealing the metal sprinkler head. At 155 degrees, the liquid in a vial expands enough to break it, causing a brass plug to dislodge from the water line and allow pressurized water to gush forth and spray off a metal deflector plate, soaking the room in short order.

“Once you see it and get your head wrapped around it, you really do begin to think how stupid it is not to do it,” Stewart says.