What does EPSS Class 10 mean?

It signifies that the emergency power system must be able to detect the normal power loss and supply power to the load within a maximum of 10 seconds (Table 2).

What is the difference between EPSS Level 1 and Level 2?

Level 1 is for systems where failure could cause loss of life or serious injury (e.g., life support in hospitals). Level 2 is for less critical systems where failure might lead to public inconvenience or economic loss (Table 1).

How often should a generator be tested?

It should be inspected weekly and tested by running for at least 30 minutes. A monthly on-load test is also required to bring the prime mover to its operating temperature (Table 4).

What is an EPSS 'Type'?

Type defines the minimum duration for which the emergency power system must supply power at its rated load, e.g., Type 2 means 2 hours, Type 48 means 48 hours (Table 3).

IS 15228

: 2002

Code of Practice for Installation, Testing and Maintenance of Emergency and Standby Power Systems

CurrentEssentialCode of PracticeBIMFire Safety · Fire Safety

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This code establishes minimum requirements for the installation, performance, testing, and maintenance of emergency and standby power systems. It provides a framework for classifying systems based on their criticality (Level), power restoration time (Class), and duration of supply (Type) to ensure reliability for life safety and critical operations.

Specifies requirements for the installation, testing, and maintenance of emergency and standby power systems for life safety and essential services.

Quick Reference Values

EPSS Level 1 CriticalitySystems where failure could result in loss of life or serious injuries.

EPSS Class 10 Transfer TimeMaximum 10 seconds to switch to emergency power.

EPSS Class 0 Transfer TimeNo interruption in power supply (UPS or equivalent).

EPSS Type 2 Fuel DurationMinimum 2 hours of fuel supply at rated load.

Weekly Test Minimum Duration30 minutes run time for the generator set.

Practical Notes

The classification of the system into Level, Class, and Type is the most critical first step, as it dictates all subsequent design and testing parameters.

Regular on-load testing using a load bank is crucial to verify that the generator set can perform under actual emergency conditions, a step that is often overlooked.

Ensure strict adherence to installation guidelines for ventilation, exhaust routing, and fuel storage to prevent safety hazards like overheating and fume accumulation.