Troy Lipp, a Montgomery County fire captain at Station 31 in North Potomac, earned $209,840 last year — more than County Executive Isiah Leggett ($180,250) and then-Fire Chief Richard R. Bowers Jr. ($190,000) and just a bit less than Police Chief J. Thomas Manger ($216,603).

That’s because Lipp collected more than $92,000 in overtime, nearly doubling his base salary of $117,570. Six of his fellow captains also hit the $200,000 mark in 2012. Of the 94 county employees who made more than $40,000 in overtime last year, 80 were firefighters, according to county records.

Montgomery’s fire department is an overtime machine, consuming 34 percent of the county’s total overtime hours, according to a recent study by the County Council’s Office of Legislative Oversight. The agency will spend a projected $16.9 million for this fiscal year, $3.7 million over budget.

A series of underlying factors drive overtime, including staff shortages and the department’s traditional 24-hours-on, 48-hours-off schedule that some cities are trying to scrap. There are also benefits in the union contract that allow firefighters to earn overtime even during pay periods when they take sick leave or are on vacation. Altogether, the numerous factors raise questions about whether county taxpayers are footing an excessive premium for fire safety.

“This is why people in the private sector look at the public sector and ask, ‘How do you get away with it?’ ” said council member Valerie Ervin (D-Silver Spring).

County officials say it is cheaper to pay overtime than hire new firefighters who come with costly health and pension benefits. The heavy overtime also reflects budget cuts that forced the department to go three years — from 2009 to 2012 — without a recruiting class. The absence of new firefighters, combined with retirements and other attrition, have thinned the service’s ranks from 1,305 in 2010 to 1,200 today.

“You cut budgets, you don’t hire — this is what happens,” said Capt. Raymond Sanchez, who earned $210,845 working at Station 7 on Connecticut Avenue in Chevy Chase.

Fire overtime in Montgomery has totaled between $12 million and $16 million annually over the last six years, averaging about 8 to 10 percent of the agency’s total personnel costs.

Overtime is a major expense for many big city and suburban departments. Fairfax County, with 1,400 career firefighters, paid out $16.7 million in fiscal 2012. In the District last year, 25 Fire and Emergency Medical Services employees, many of them mechanics, combined to earn more than $1 million in overtime. Pittsburgh Controller Michael Lamb called his city’s $10.8 million overtime tab in 2010 “out of control.” In 2011, a San Francisco fire lieutenant made $221,000 in overtime, propelling his gross income to $363,000.

In Montgomery, fire commanders said this is the cost of running an emergency service that must be staffed at all hours of the day and have enough personnel in stations to safely operate trucks and other vehicles.

With vacation, sick leave, training and other absences, it would take 4.5 career firefighters to fill each of the 282 slots every weekday from 7 a.m. to 5 p.m. for a full year to avoid overtime. (On nights and weekends, when volunteers fill the gaps, that falls to 249 slots.)

“Overtime is a must for any public safety agency that guarantees a level of readiness,” said Montgomery Fire Chief Steve Lohr.

Even if the department’s ranks expanded so that it could pay “straight time” for every slot — which would take an estimated 147 new hires — officials said it still couldn’t cover all of its staffing needs because there aren’t enough people with the required training and expertise.

Sanchez, 51, is a paramedic, a member of the Hazardous Incident Response Team and a peer crisis counselor. Lipp, 47, the son and grandson of firefighters, is also a paramedic and on the Urban Search and Rescue Team, which has been deployed to such emergencies as the attack on the Pentagon on Sept. 11, 2001, and May’s partial collapse of the Westfield Montgomery mall garage that was being renovated.

Lipp said the public knows about his earnings but doesn’t know the whole story.

“The perception can be misconstrued without context,” said Lipp, who has 25 years in the service and has heard the overtime debate for years. “If you look at it on the surface, you can draw conclusions that are not accurate.”

While firefighters are occasionally ordered to remain on the job if a replacement can’t be found, overtime is mostly voluntary. Regulations require that slots be offered first to qualified firefighters who make the least money, but not everyone wants extra hours, officials said. And there are those like Sanchez and Lipp who raise their hands every time.

The system can make for some extraordinarily long hours. Most Montgomery firefighters work a 48-hour week, with 24 hours on duty (7 a.m. to 7 a.m.) followed by two days off. Over one two-week stretch in May, for example, Lipp worked his regular 96 hours, along with an additional 71 hours of overtime, 13 as a paramedic. During that time, his hourly rate went from $47.10 to $70.65.

Overtime earnings have also been boosted by contracts Montgomery officials have negotiated with the International Association of Fire Fighters Local 1664, one of the county’s most politically influential public-employee unions.

Federal labor law allows localities to require up to 53 hours of “straight time” in a two-week period before firefighters are eligible for overtime.

But the county’s contract with the International Association of Fire Fighters Local 1664 triggers overtime at 48 hours. It also provides that hours paid — not just hours worked — count toward the 48-hour threshold, something not required by federal labor law but a common feature of collective-bargaining agreements in the fire service. In other words, a firefighter on a sick day, vacation or other earned leave is still working toward the 48-hour threshold.

The council report found that between January 2011 and June 2012, more than 300 firefighters received overtime during pay periods in which they worked just half of their regular hours, meaning two 24-hour shifts. More than 150 worked entire two-week pay periods with all overtime and no regular shifts.

John Sparks, president of the Montgomery firefighters union, said such situations are rare and not abusive.

“It’s not like we’re freeloading,” Sparks said.

In addition to the 144 hours of sick leave firefighters accrue each year — the equivalent of six 24-hour shifts — recent collective-bargaining agreements have further expanded paid leave, adding more personal and sick leave. It was added when Leggett, under pressure to cut costs because of the recession, asked the union to renegotiate scheduled salary increases. In 2010, the contract was amended to give firefighters 48 hours of annual personal leave and 72 hours of compensatory leave on a one-time basis.

The following year, the union negotiated a one-time credit of 48 hours of compensatory time and a maximum four episodes of sick leave without a doctor’s note, up from three. The contract was also modified to allow fire personnel to hold second jobs while on disability leave. The outside employment must predate the injury and be judged as not hindering recovery.

The accumulation of leave means that the average firefighter is available for work about 78 percent of the time, the lowest level of any county department, according to a study of overtime and leave practices released in March by the County Council’s Office of Legislative Oversight.

Sick leave is a likely driver of overtime costs in the fire service and other county agencies. A section of the current firefighter contract describes examples of sick-leave abuse that could result in disciplinary action. They include “repeated use” of sick leave when requests for vacation or compensatory leave are denied. The contract also cites calling in sick before or after scheduled days off.

The agreement provides for sick-leave restrictions and written reprimands when firefighters are found to be abusing the system. During the 18-month period studied by the council staff, 13 firefighters had their sick leave restricted. None were formally reprimanded.

Leslie Adams, a former Montgomery deputy fire chief, said high rates of sick leave can be a red flag. “If there is excessive sick leave that will increase overtime,” said Adams, president of Public Safety Solutions, a consulting firm. He said he was not familiar with the details of Montgomery’s current situation, but described the abuse generally as, “ ‘Hey, I’ll call in sick so you can get a day of overtime.’ Management has to be cognizant of those things.”

The study recommended that county officials consider limits on overtime in pay periods where leave is taken. Sparks said the vacancies still have to be filled by someone, meaning that “the overtime cost will be incurred regardless of how many regular hours a particular employee has worked.”

One change that might roll back overtime is a different work schedule. The 24-hours-on, 48-hours-off system is a legacy of an era when travel times to the station house were lengthier and departments didn’t want to get caught shorthanded during shift changes.

Shorter shifts would require more personnel, but could pay off in the long term with lower overtime expenses. Experts say shorter shifts could also minimize accidents caused by fatigue and encourage firefighters to live closer to work.

But any discussion of changing shift arrangements is usually met with pushback. Firefighters have organized their lives around a system that calls for two long workdays per week. About 70 percent live outside the county, some as far away as West Virginia and central Pennsylvania. Many hold second jobs.

Sparks said the prospects of such a transition are remote.

“One thing I’ve learned in the fire service is that firefighters hate change.”