Hospital Generator Requirements

RULE #1: If you are an acute care facility or other healthcare occupancy deemed to be a Type 1, 2, or 3 installation by NFPA 99, Health Care Facilities Code©, your Emergency System (Life Safety and Critical Branches) will be online within 10 seconds (Type 10) of a power outage and will be able to operate without refueling for a period established by the AHJ (Class X).

NFPA 99, Type 1 and Type 2 essential electrical system power sources shall be classified as Type 10, Class X, Level 1 generator sets per NFPA 110, Standard for Emergency and Standby Power Systems.

Essential Electrical Distribution System

The Emergency Power Supply System (EPSS) must be designed and maintained to provide electrical power to transfer switches of the Essential Electrical Distribution System (EEDS). These transfer switches are wired to accept either normal power or ‘emergency’ power. Only prescribed groupings of all the wiring, or circuits, in a facility are connected to these transfer switches. Those circuits on the EEDS are grouped into the Life Safety, Critical, and Equipment Branch.

A thorough review of NFPA 99,,, and should determine which equipment is allowed on each system.

Life Safety Branch

The Life Safety Branch supplies power to those circuits used for egress lighting, alarms and alerting systems, emergency communication, generator set lighting, and elevator control.

Critical Branch

The Critical Branch supplies power to those areas and receptacles associated with maintaining medical treatment. Transfer switches of the Life Safety and Critical Branch operate automatically to restore power to equipment and receptacles within 10 seconds of a power outage.

Equipment Branch

Transfer switches of the Equipment System are set to operate either automatically (but delayed) or manually. For the former, the delay time for transferring power to loads is determined by design engineers in coordination with facility needs and the manufacturer of the alternate power source.

Hospital Generator Requirements

Emergency Generator Testing Requirements

The purpose of monthly testing is to verify that the EPSS can supply service to all emergency and equipment systems, within the prescribed time after a power outage and for the duration specified by the AHJ (authority having jurisdiction). Most facilities perform the weekly inspection before the monthly load test because the temperature of the engine and fluids is cooler.

NFPA 110, Standard for Emergency and Standby Power Systems

NFPA 110, 8.4.1* EPSSs, including all appurtenant components, shall be inspected weekly and exercised under load at least monthly.

NFPA 110,* Diesel generator sets shall be exercised using one of the following methods:

  • Loading that maintains the minimum exhaust gas temperatures as recommended by the manufacturer.
  • Under operating temperature conditions and at not less than 30 percent of the EPS standby nameplate kW rating.

Exercising a diesel without load can promote “wet stacking”; however, not exercising a diesel or spark ignited generator promotes more problems than not exercising at all. According to Cummins, exercising the engine “is required to maintain a coating of lubricating oil around engine bearings and to maintain corrosion inhibitor throughout the cooling system, therefore extending the generator package life.” The other components of the EPSS, including the automatic transfer switches, day tanks, etc., must be inspected each week as well as exercised monthly. Use the Weekly Inspection Checklist coupled with the checklist provided by the manufacturers. As an alternative, use the inspection sheet found at NFPA 110, A.8.3.1(a) and (b).

Hospital Generator Testing Requirements

Some facility managers start the EPS just once every 20-40 days for the “monthly” exercise, or test. While this procedure fulfills the minimum intent of the standards, a more conservative approach is to start and exercise the EPS for a period each week, under load if possible, allow the water temperature to rise to its “loaded temperature,” normally about 5 minutes, then shut the unit down. (If the EPS has been exercising under a heavy load, drop the load first and let the engine cool a minimum of 5 minutes before shutting it down.) If you are running a diesel EPS without load, or with a load below 30% of nameplate, we recommend exercising the set no longer than necessary to achieve “idling temperature.” Normally, this should take no longer than 5-7 minutes.

NFPA 99, Generator sets shall be tested 12 times a year with testing intervals between not less than 20 days or exceeding 40 days. Generator sets serving emergency and equipment systems shall be tested in accordance with NFPA 110, Standard for Emergency and Standby Power Systems, Chapter 8.

All the EPSS components will be exercised automatically during the 20-40-day EPS exercise period, with the possible exception of some automatic transfer switches and alternate power feed circuit breakers. If normal power is available at the transfer switches, the power source must be “switched” using the test switch or by opening the normal power breaker feeding a particular switch.

Properly Trained Personnel

What should you know about current emergency power requirements? Much more than ten years ago with more in the years to come. Each component of the EPSS; cooling, electrical, fuel, lubrication, starting batteries and battery charging subsystems, all have their own unique needs.

The operation of the emergency power supply system (EPSS) depends on individuals well versed in maintenance, testing, and compliance. Each facility should have one person who is familiar not only with the manufacturer’s guidelines but the standards governing maintenance and testing as well.

NFPA 99, Test Personnel. The scheduled tests shall be conducted by competent personnel to keep the machines ready to function and, in addition, serve to detect causes of malfunction and to train personnel in operating procedures.

NFPA 110, 8.4.8 The routine maintenance and operational testing program shall be overseen by a properly instructed individual.

Frequently Asked Questions

Am I performing all maintenance activities adequately to ensure the EPSS will start & run when needed?

Do I have the proper EPSS documentation and records for inspections, maintenance, and testing?

Did I perform all monthly and triennial tests properly? Will AHJ surveyors accept the testing reports?

Does my EPSS installation meet NFPA requirements for lighting, cooling, ventilation, fuel supply and storage?

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Emergency Generator Maintenance and Operation
Emergency Generator Testing and Compliance

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