When the power goes out and city dwellers are left in the dark, people assume  they won’t be stuck in cold apartments for days. Just as we expect our hospitals to have  backup power generators to save patients who are on life support systems or in  the midst of surgery, we also count on generators to save residents of  high-rises and other multifamily communities during a blackout or another power  interruption.  

 In times of emergency, like a power outage due to foul weather or a fire in the  building, certain aspects of many multifamily structures must function  properly; steps must be free and clear so people can use them, and doors to  stairways must function. In larger buildings, common areas, corridors and  elevators usually are illuminated through the power provided by an emergency  generator.  

 Though some older buildings in Chicago have thus far opted out of having a  backup generator installed in their properties, many newer complexes often have  such a power backup, and many have been required by law to put in a generator.  In Chicago, any building 300 feet or taller must have an emergency service of  some kind. Condo buildings in the city are considered a high-rise if they are  80 feet or taller, and such buildings are also required to have an emergency  generator. For most buildings required to have such a service, it almost always  means a standby generator is needed, says Tim O’Connell, sales manager for Hodgkins, IL-based Cummins Power Generation, a  supplier of generators and electrical supplies.  

 Powering Up

 There are two kinds of generators a building’s staff use in a power outage: stationary sets or portable sets. A portable  generator could be used by the staff of the building during an emergency or  during construction work, if the structure does not have a stationary set.  Portable sets vary widely in quality, and can last anywhere from four to ten  years. The generating capability of stationary sets in residential buildings  can range from 60 kilowatts to 3,000 kilowatts. These units can cost as little  as $40,000 or as much as $1 million, and last 20 to 30 years, O’Connell says.  

 How long a generator lasts is partly dependent upon how much it is used, says  Raymond S. Groban, co-owner of Chicago-based Groban International, which sells  generators and has been in business since 1948. “The average number of hours of use/test on a standby generator is 300 hours a  year. Part of that time comes from the exercising—we recommend that generators be exercised twice a month for an hour or two,” he says.