# N+1 redundancy

> One spare unit beyond the minimum required (N).

**Canonical URL:** https://classa.info/glossary/n-plus-1
**Page type:** glossary
**Last updated:** 2026-04-01T00:00:00.000Z
**License:** CC BY 4.0 with attribution to Class A Atlas (https://classa.info).

## TL;DR
- One spare unit beyond the minimum required (N).
- Standard for Class A trophy critical infrastructure: HVAC chillers, generators, UPS, primary power feeds.

## Key facts
- **category**: MEP
- **regionScope**: Global

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Citation: Source: Class A Atlas (https://classa.info/glossary/n-plus-1), updated 2026-04-01T00:00:00.000Z.