An entire block in the Sunset district could easily go up in flames due to the combination of wind, closely packed wood-frame houses and illegal marijuana growing operations, authorities say.

Since March, police have uncovered sophisticated growing operations in 36 homes in the quiet, foggy neighborhood and arrested 44 people. In every case, the conditions in the indoor pot farms imposed a serious fire risk, Fire Department Chief Joanne Hayes-White said.

Growers use ballasts, also known as battery packs, to power their operations. The ballasts — which power lamps, fans, air filters, water filtration systems and exhaust fans for hydroponic gardening — are often installed improperly, leading to fires sparked by an overload of energy. Faulty wiring used to steal electricity or bypass PG&E meters to avoid suspicion is a common cause of electrical fires, SFPD officials said. Additionally, rows of lamps that simulate sunlight for the plants can radiate as much heat as a pizza oven, which adds to the danger.

“Quite frankly, we can end up burning an entire city block,” police Chief George Gascón said.

Growers frequently nail plywood over windows from inside the home in order to control growing conditions, according to fire officials. This means the blaze is often fully developed and particularly dangerous for responding firefighters.

In May, a firefighter paramedic was seriously injured in a Bayview warehouse conflagration sparked by faulty wiring powering an illegal growing operation. Authorities say similar fires in the dense Sunset district could spell disaster.

Taraval Police Station Capt. Paul Chignell said pot growers may be drawn to the Outer Sunset due to the ocean breezes, which mask the smell of marijuana.

Of the 36 houses raided since March, four were legitimate medical marijuana operations, Chignell said. In those instances, nobody was arrested and the cases were given to a task force that handles code violations.

In the past years, firefighters have typically responded to about two fires annually sparked by growing operations, Fire Marshal Barbara Schultheis said. This year, there have been four.

Men on the streets

Details on the Taraval Police Station’s efforts to find and abate marijuana growing operations:

36 Houses raided this year

34 Number of raided houses that were rentals

44 Arrests made

43 Charges filed

8,229 Plants seized

$84,810.46 Cash seized

20 Weapons seized

Sources: SFPD, District Attorney’s Office