OTDR (Optical Time-Domain Reflectometer) testing is the standard method for verifying fibre optic link quality on backbone and riser installs. If your specification says “fibre tested and certified,” OTDR traces are usually part of what the consultant expects at handover.
What an OTDR does
An OTDR sends a pulse of light down a fibre and measures reflections and loss along the length. The result is a trace — a graph showing splices, connectors and faults by distance.
Unlike a simple light source and power meter test (OLTS), OTDR can:
- Locate faults and bad splices by distance
- Verify splice loss along a long run
- Support troubleshooting after cutover
OTDR vs OLTS — when each applies
| Test | What it measures | Typical use |
|---|---|---|
| OLTS (light source + power meter) | End-to-end insertion loss | Short links, patch cords, acceptance against loss budget |
| OTDR | Events and loss along the fibre length | Backbone, risers, long campus links, splice records |
Many UK commercial specs require both — OLTS for loss budget sign-off, OTDR for trace records on backbone pairs.
What should be in the handover pack
For each fibre pair (or as specified):
- OTDR traces at required wavelengths (e.g. 1310/1550 nm on single-mode)
- Insertion loss results against consultant thresholds
- Splice records with location references
- As-built fibre schedules and cabinet port maps
Incomplete trace packs are a common snagging item at PC on logistics and office backbone projects.
Tier 1 and Tier 2 testing
You may see specifications reference Tier 1 (OLTS loss) and Tier 2 (OTDR) testing — particularly on data centre and campus links. Confirm which tier your consultant requires before mobilisation, not at handover.
Common site issues OTDR catches
- Excessive bend radius in tray
- Poor fusion splice loss
- Wrong connector type or contaminated end-face
- Patch lead mismatch between install and test reference
Our fibre optic service includes fusion splicing, termination and test documentation to your specification.
Representative project
Our North West logistics hub case study included 1.4 km OS2 backbone — fusion spliced, tested and handed over with full trace documentation before WMS commissioning.
For copper/fibre strategy on mixed installs, see Fibre vs copper for commercial networks.
Fibre programmes in Birmingham and Manchester
We deliver backbone and horizontal fibre across the Midlands and North West:
Contact us for fibre scope, test requirements and quotation.