On Windmill Ridge Road in Plant City, one 2,400-square-foot home uses $120 a month in electricity. Another uses $220 a month.
Tampa Electric Co. estimates a third home used about $4,200 a month in electricity.
But the electricity there was stolen - used to power a marijuana grow house with 22 grow lights at 1,000 watts each and two 5-ton air-conditioning units, investigators say.
Such homes are common. There's no way to tell exactly how much power or money is stolen each year from TECO, but the company's chief theft investigator said many he helps uncover involve grow houses.
John Hammerberg supervises TECO's revenue protection department, which helps identify cases of stolen electricity.
Hammerberg said his department's investigators will work about 600 to 700 electricity theft cases this year. About 50 will be grow houses.
The average restitution for a simple case of electricity theft is about $1,000; the average restitution for a grow house is about $20,000.
"It's a huge amount of money that we're losing," Hammerberg said.
Many in law enforcement consider grow houses a burgeoning problem. In Hillsborough and Pinellas counties last year, 102 indoor grow operations were busted and nearly 8,000 plants were seized, according to a report by the state's Office of Agricultural Law Enforcement.
Pasco had 27 busts in which about 2,000 plants were seized.
Hillsborough County deputies discovered more than 20 grow houses and seized more than $5 million in marijuana in recent months.
One night last week, deputies discovered 252 pounds of marijuana - valued at about $1.1 million - in three rooms of a grow house, Maj. Albert Frost said.
When arrested, grow house owners often are charged with theft of electricity, a first-degree misdemeanor.
Not all grow houses steal electricity, but doing so can save owners thousands of dollars a year and bypass an obvious flag to law enforcement.
An electric bill at an average-size home might run $150 a month. An average grow house steals about $2,000 to $3,000 a month from TECO. Some bigger operations might steal $10,000 to $15,000 a month, Hammerberg said.
Through April, TECO helped uncover about 240 cases of electricity theft this year - not including grow houses - and billed about $340,000 in restitution.
TECO also helped uncover 17 grow houses and billed about $395,000 in restitution in those cases.
"I've seen five 5-ton air-conditioning units at one grow house," Hammerberg said.
Law enforcement generally identifies a possible grow house, then comes to TECO's revenue protection department.
Often, Hammerberg said, his department can go to the scene with officers and try to find an illegal tap.
Stealing power is not difficult, but homes can become fire hazards if wired the wrong way, Hammerberg said.
Some grow house owners hire licensed electricians to help bypass electric meters. Others get help from friends or try to do it themselves, he said.
People use all kinds of tricks to avoid detection, including putting up fences around homes so others can't see several air-conditioning units.
Investigators catch thieves in a variety of ways, often using tips from meter readers and conscientious neighbors. Sometimes a computer program shows something amiss with a meter that measures usage.
Hammerberg said the industry estimates that stolen power is equivalent to about 5 percent to 6 percent of a utility's annual revenue.
Across the state, investigators identified more than 1,000 grow houses in 2008. In 2003, they found 228. Hillsborough County had the second-highest number of plants seized at grow house busts in the state last year.
Pot is still grown outside, but such sites are more easily detected, authorities say. Grow houses are harder to spot and have been found everywhere, from low-income neighborhoods to upscale addresses, detectives said.
"That's one thing that makes it so difficult to find," he said. "From the small shoddy little house to the really nice houses in very nice neighborhoods; we've found them in gated communities, we've found them in normal neighborhoods. Places where people keep the yards nice, where everything looks like a normal house."