Bulk Fiber Cable: Buy by Loss Budget, Not by Metre
Quick answer / TL;DR: Short answer: choose OS2 single mode for runs beyond a few hundred metres and OM3 or OM4 for short building links; buy pre-terminated assemblies where the route allows, because field termination costs more in labour than in materials. Require test data per fibre, plan a loss budget of about 0.3 dB per splice and 0.2 dB per connector, and keep spare length at both ends.
Single-mode patch cords: yellow jacket, LC/UPC, OS2 9/125.Bulk fiber is bought on a spool or cut to length. The purchasing decision is driven by the loss budget and the connectorisation plan, not by the price per metre.
Fiber that arrives without test data is a liability on site.
Selection
| Type | Reach at 10G | Use |
|---|
| OS2 | Kilometres | Campus and access |
| OM3 | 300 m | In-building |
| OM4 | 400 m | Data centre |
| OM5 | 400 m plus | Wavelength division |
The reach figures are the reason most buildings use OM4 for links under a few hundred metres and OS2 beyond that.
Buying and Terminating
- Pre-terminated where the route permits
- Test report per fibre
- Spare length at both ends
- Splice closure planned
- Bend radius respected
Pre-termination moves the quality problem into a factory with test equipment, which is usually the right trade.
Real-World Applications
A warehouse linking two buildings 400 m apart uses OS2 with splices at each end. A data hall uses OM4 trunks between racks.
Standards and Verification
| Reference | Relevance |
|---|
| ITU-T G.652 | Single mode |
| ISO/IEC 11801 | Classes |
| IEC 61300-3-4 | Attenuation |
Loss figures for a specific cable are not provided in the knowledge base. Require test data.
References
- ITU-T G.652, Characteristics of single-mode fibre
- ISO/IEC 11801-1, Generic cabling
- IEC 61300-3-4, Attenuation measurement
Practical Notes
Record measured loss per fibre at handover. It is the baseline for every future fault.
Related reading: fiber cable — blogs/news/fiber-cable
Related reading: bulk cable — blogs/news/bulk-cable
Related reading: powered fiber cable — blogs/news/powered-fiber-cable
Frequently Asked Questions
Spool or cut length?
Spool for long pulls, cut length for patch work.
OS2 or OM4?
OS2 beyond a few hundred metres.
Is pre-terminated better?
Usually yes, for quality and labour.
What loss is normal?
About 0.2 dB per connector.
Sourcing cables for a project, a store, or a private-label line? Contact our B2B sales team for specifications, certification evidence, and volume terms – FOB and CIF options available. Request a quote or sample.
