SAIFI
System Average Interruption Frequency Index – average number of supply interruptions per customer in a period
What is SAIFI?
The System Average Interruption Frequency Index, known as SAIFI, is the average number of supply interruptions each customer experiences in a period. It is a standard reliability measure for utility networks.
Where SAIDI shows how long customers are without supply, SAIFI shows how often it happens.
How this KPI is measured
- Function
- Operations & Supply Chain
- Sub-function
- Asset Reliability
- Industry
- Energy & Utilities
- Type
- Lagging
- Impact
- Operational
- Unit
- int/customer
- Measurement frequency
- Monthly
- Formula
- Sum of customers interrupted per event / Total customers served
How to calculate it
Add up the number of customers interrupted in each event and divide by the total number of customers served.
For example, if 150,000 customer interruptions occurred across 100,000 customers, SAIFI is 1.5 interruptions per customer.
Use the same outage rules as for SAIDI, following your regulator's definitions.
Where it is used
Reporting reliability
Meet regulatory reporting.
Finding frequent-fault areas
Target repeated failures.
Guiding investment
Justify network improvement.
How to improve it
Tips and common mistakes
- Read with SAIDI.
- Use consistent definitions of an interruption.
- Look at repeat outages for individual customers.
More Operations & Supply Chain kpi library
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