How to Size an Emergency Generator for a Restaurant

Anuj Srivastava
4 Minutes Read
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    Emergency generators play a very important role in buildings, ensuring that all equipment necessary for occupant safety remains operational in case the main power supply is interrupted. However, restaurants are a special case given their high occupant density, as well as the presence of personnel and combustion-based equipment in reduced kitchen spaces.

    In Chapter 27, the New York City Building Code provides a list of equipment required to have an emergency power supply. In addition, the code also requires a standby power supply for building systems that would create inconvenience or significant discomfort if they cease to operate, even if major safety hazards are not involved.

    Restaurants are often part of larger constructions such as malls or high-rise commercial buildings. In these cases, there are separate emergency and standby power requirements for the restaurant and the commercial building it is part of. These requirements are important to know if you are leasing commercial space for a restaurant, where you may have no control over broad building systems, and it is better to ensure that emergency and standby power requirements are already covered.

    In general, the NYC Electrical Code only allows batteries to be used as an emergency power supply for lighting. The battery system must be designed to power emergency lighting for at least 1.5 hours at full output and without allowing their voltage to drop below 87.5 percent. To use batteries as an emergency power supply for other building systems, it is necessary to ask the NYC Department of Buildings for permission and receive approval. It is important to note that this requirement applies for uninterruptible power supplies (UPS) as well, if they are used to provide emergency power.

    Restaurant Loads to Consider for an Emergency Generator

    Restaurants are classified by the NYC Department of Buildings under occupancy Group A (Assembly), specifically in subgroup A-2, which is for locations intended for food or drink consumption. All Group A occupancies are required to have an emergency power supply for voice and alarm communication systems.

    Exit signs and means of egress illumination must also be provided with an emergency power system, and batteries are allowed instead of a generator if they meet the requirements established in the NYC Electrical Code. The emergency lighting system must be capable of delivering an illuminance level of at least one foot-candle or 11 lux.

    If elevators are present, emergency power is required for their controls, cab lights, ventilation systems and any other equipment required for operation.

    Restaurant Loads to Consider for a Standby Generator

    The NYC Building Code also provides a list of loads required to have a standby generator, and they must be counted if present in a restaurant:

    • Smoke control systems
    • Elevators
    • Horizontal sliding doors
    • If the restaurant has a membrane structure such as an outdoor tent, standby power must be provided for auxiliary inflation systems.
    • Smokeproof enclosures must be supplied with standby power for their mechanical ventilation and automatic fire detection systems.
    • Elevator shaft pressurization systems

    Requirements for Restaurants in Malls and Other Buildings

    When restaurants are part of a larger building, additional emergency and standby power requirements may apply. The NYC Building Code provides requirements for three cases: covered malls, high-rise buildings and underground buildings.

    If you own not only the restaurant but the entire building, make sure all applicable requirements are met. On the other hand, if you are purchasing or leasing commercial space for a restaurant, ask an engineering design or consulting company to check the surrounding installation. Even if your restaurant is properly equipped with emergency and standby power, you can only guarantee safety for your customers if the rest of the building complies as well.

    Covered Mall Buildings

    If a restaurant is part of a covered mall building with an area above 50,000 square feet, the mall must have a standby generator capable of operating the voice and alarm communication system. Keep in that the restaurant’s voice and alarm communication systems require an independent emergency power supply - standby power only applies for the surrounding mall.

    High-Rise Buildings

    When a restaurant is located inside a high-rise building, it is important to ensure that the emergency and standby generators are sized with enough capacity to power the following loads.

    • Emergency generator loads: Exit signs, means of egress illumination, elevator car lighting, emergency voice and alarm communication systems, automatic fire detection systems, fire alarms and all fire pumps that are electrically powered.
    • Standby generator loads: Fire command center power and lighting, ventilation and fire detection systems for smokeproof enclosures, elevators and stair pressurization.

    Underground Buildings

    In the case of underground buildings, the emergency power requirements are the same as in high-rise buildings, with the difference that electrical fire pumps are now required to have standby power, not emergency power. Other than fire pumps, the following equipment must be counted when sizing the standby power generator:

    • Smoke control systems.
    • Smoke-proof enclosures: Automatic fire detection and mechanical ventilation.
    • Elevators
    • Stair pressurization systems


    Emergency and standby generators in New York City are subject to requirements from many standards and codes, including the NYC Building Code, Fire Code and Electrical Code. They must also meet National Fire Protection Association (NFPA) standards 110 and 111.

    If you are planning to build a restaurant in NYC, or are looking for a commercial space that can be conditioned for that purpose, make sure you get in touch with a qualified design professional or engineering firm. That way you ensure safe conditions for your customers by sizing emergency and standby generators properly, and can also verify that the installation around your restaurant is safely designed as well.

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