Emergency Generator Systems in Chicago: A Lifesaver

Michael Tobias
4 Minutes Read
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    Imagine a condition where there's a power outage, and there's no power backup. It would take you only a few moments to come up with all the severe consequences that can arise in case a generator is not available during emergency situations. Generators can be a lifesaver and prevent discomfort and tragedies during emergency situations or power interruptions from the local electric utility company in hospitals or multifamily residential apartments or large commercial buildings.

    During emergency situations like a power outage or fire inside a large building, certain areas like corridors, staircases, elevators, and common areas depend on the emergency generator for the lights to keep running.

    Chicago building codes require hospitals and large complexes more than 300 feet tall and condos (any building taller than 80 feet) to have an emergency generator system. This also means that a standby generator is also needed alongside the emergency generator.

    In the case of Chicago, article 700 makes emergency generator systems compulsory for both new and old buildings. The code includes table 18-27-700.5 which details Emergency System Type Expected By Use. Here's a summary of the code:

    • All residential buildings of more than 80 feet height have to render an approved, on-site backup source of power supply for the emergency lighting and exit signs.
    • High-rise buildings and other buildings need to follow with high rise laws under 300 ft in height, the backup source of power supply must be from a totally autonomous service company main or from an on-site generator complying with Article 701
    • For every high rise building in Chicago that is over 300 ft the backup source has to be from an on-site diesel generator that follows standards of Article 701 B
    • There has to be an on-site power supply source for every existing and new high-rise building. Also, it has to be independent of the service source to power escape and exit signs. And by Sections 18-27-700.33(h) the power supply source on site has to be a generator or by Section 18-27-700.33(i) an inverter system.

    Every generator shall adhere to the following:

    - In case of high-rise builder under 300ft, they can have natural gas or diesel fuel as fuel supply and must follow with Section 18-27-701.16

     - High rise buildings 300 ft or over shall be needed to have diesel fuel as the fuel supply and must follow Section 18-27-701.1

    Basic Requirements

    Few Chicago building codes are compulsory regardless of the fact whether the generator is a primary generator or a secondary generator:

    • The generator must have enough fuel for it to operate for at least 6 hours at full load
    • The preferred type of fuel for the generator is diesel and should be either stored in a tank directly connected to the generator or in the generator room.
    • All generators have to meet the UL 2200 standard by Underwriters Laboratories.
    • The generator and the equipment associated with it must be kept in a room different than the main electric room. This room must have a fire barrier rated accordingly in compliance with Chicago building codes.
    • The fuel tanks present in the room must be used only for the generator. Similarly, the only piping present in the room should be that of sprinkler systems, and other system piping is allowed only if they go uninterrupted.
    • The only way multiple generators are allowed to share fuel supply is when they are providing power in case of emergencies.
    • Electrical components such as the Automatic Transfer Switch and the equipment connected with it must be in a different room than the generator. In case the transfer switch is not located at the load it must be in a room with similar conditions as that of the generator room.

    When Are Emergency Generator Systems Necessary?

    Like we have mentioned above, emergency generator systems are a legal requirement for all electrical systems in where a power cut can be a threat to human life. According to Chicago Building Codes, emergency generator systems are needed in the following situations:

    - In Assembly groups A which are basically locations where people assemble for some cause.

    - Every building structure even tents must have their exit signs backed up by emergency generators.

    - All complexes r buildings in which toxic or flammable materials are stored must have emergency power backup.

    - In case of high-rise and buildings located underground, they are compulsory to have a system for backup and emergency power.

    In institutions like prisons or mental facility, all the doors should have an emergency power backup for exit sign illumination.

    Elevator components like control panel, lights, ventilators, and other equipment must have emergency power backup in all cases.

    Special Requirements For Emergency Power For Residential Units, Business Units, and Educational Institutes

    All large residential units must be outfitted with both emergency and standby power, as well Business units and Educational institutions that suffice the following conditions:

    - Have the floor more than 75 feet and in use above the lowest access for the fire trucks.

    - Areas more than 15,000 sq. Ft. Each floor total area of 100,000 sq. Ft.

    The emergency generator systems in these units must be able to power exit signs, escape lights, elevator car lights, alarm systems, automatic fire detectors, fire alarms, and electric fire pumps.


    In any building where an emergency generator system is being installed, it is very important to follow the codes, not only for the project to be approved but also for the safety of the residents or occupants of the building.

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