Emergency Power Supply System (EPSS)
What it means.
An emergency power supply system, or EPSS, is the complete system that delivers backup power to a building: the generator set (the EPS), the transfer switches, the switchgear, the fuel supply, the starting system, and the conductors between them. NFPA 110 regulates the EPSS as a whole, which is why a generator that starts perfectly can still fail an inspection if the transfer switch or fuel system is not tested.
Governing standard
NFPA 110 defines both the EPS (the power source itself) and the EPSS (the full system) and applies its Chapter 8 testing and record-keeping requirements to the system, not only the engine.
Related service
Hedgehog Power Systems handles this under Control Panel & ATS Modernization.
Also in the glossary.
NFPA 110 Level 1 and Level 2
NFPA 110 classifies an emergency power supply system by Level, Type, and Class. Level 1 covers systems where f...
Wet Stacking
Wet stacking is the buildup of unburned fuel and carbon in a diesel generator’s exhaust system, caused by runn...
Automatic Transfer Switch (ATS)
An automatic transfer switch, or ATS, is the device that detects a utility power failure, disconnects a facili...
Breaker Trip Time Testing
Breaker trip time testing measures how quickly a circuit breaker opens under a simulated overload or fault, co...
Power that stays on.
Preventive maintenance, testing, and repair for standby generators across Illinois and the Midwest. One call reaches a technician, not a call center.