Service Delivery
Electricity Reliability SAIDI and SAIFI
SAIDI and SAIFI are the regulated indices NERSA uses to judge electricity supply reliability, and they translate operational outages into auditable performance numbers.
Why SAIDI and SAIFI Matter
The System Average Interruption Duration Index and System Average Interruption Frequency Index are the standard measures of how often and how long customers lose power. NERSA benchmarks these against licence conditions, and they form part of the municipality's service-delivery performance reporting. AuditPro Core computes both indices from outage records and reconciles them to the reported indicators, giving oversight bodies a defensible view of grid reliability.
The Numbers
AuditPro Core renders this view from your tenant's live, tamper-evident records. The figures below are illustrative sample data.
SAIDI
48 h
▲ 6 h
SAIFI
31
interruptions/yr
CAIDI
1.5 h
NERSA target met
No
SAIDI trend by quarter
Reliability by feeder
| Feeder | SAIDI h | SAIFI |
|---|---|---|
| Feeder 1 | 22 | 14 |
| Feeder 2 | 15 | 9 |
| Feeder 3 | 11 | 8 |
Figures shown are illustrative sample data for demonstration. AuditPro Core renders these views from your own tenant's live, tamper-evident records.
SAIDI explained
SAIDI is the average total minutes a customer is without supply over the period. A rising SAIDI signals longer restoration times or more severe events, regardless of how frequently they occur.
SAIFI explained
SAIFI is the average number of interruptions a customer experiences. High SAIFI with low SAIDI suggests frequent brief trips, often pointing to protection or network-stability issues.
NERSA benchmarks
NERSA publishes reliability expectations that licensed distributors are measured against. Sustained breaches can affect licence standing and signal under-maintained infrastructure.
Data integrity of outage logs
Both indices are only as good as the outage capture behind them. Missing or mis-timed events distort the indices and undermine the reliability assertion at audit.
How AuditPro Core Bridges the Gap
- Index computation: SAIDI and SAIFI are calculated directly from outage logs using a transparent, recomputable method.
- Benchmark comparison: results are plotted against NERSA expectations so breaches are immediately visible.
- Traceability to source: each index value links back to the underlying outage events for audit verification.
- Continuous monitoring: reliability trends are tracked quarter on quarter to flag deteriorating feeders early.
Key Takeaways
- SAIDI measures duration, SAIFI measures frequency; reading them together diagnoses the network problem.
- The indices are only reliable if the underlying outage capture is complete and correctly timed.
- Persistent NERSA-benchmark breaches signal infrastructure neglect, not just bad luck.
- Recomputable indices linked to source events withstand AOPO scrutiny.
See This on Your Own Data
AuditPro Core renders this dashboard from your tenant's live, tamper-evident records — every figure traceable to source.