The short version
Most office cabling is copper. Fibre does a different job: it links the places where the switches live. A riser between floors, a run from the main comms room to a second rack at the far end of a warehouse, or a trench to the building across the yard are all typical fibre jobs.
Use fibre where a copper run would go past 100 metres, where the link crosses between buildings, or where the backbone needs 10 Gbps and more. For a new backbone, single-mode fibre is usually the better long-life choice. Multimode is fine for short runs inside one building.
Fibre cabling is also a different thing from the fibre internet service a carrier delivers to the building. The carrier owns its fibre up to its termination point, and your cabler is not allowed to touch it.
Two things called “business fibre”
Searches for enterprise fibre mix up two separate purchases.
| Fibre cabling | Fibre internet service | |
|---|---|---|
| What it is | Cable you own, inside and between your buildings | A carriage service delivered to the building by a carrier |
| Who installs it | A registered cabler you engage | The carrier or NBN, ordered through a provider |
| What you pay | A one-off installation | A monthly service charge, sometimes with a build cost |
| Where it ends | Your patch panels and switches | The carrier’s network termination device |
This guide is about the first column. If you came here for a fibre internet service, read NBN Enterprise Ethernet explained or what business fibre costs instead. Most sites that buy a high-grade fibre service also need some fibre cabling to carry it from where it lands to where the network equipment is.
Where fibre is used inside and between buildings
Backbone and riser links. In a multi-floor building, each floor or wing often has its own rack. Fibre in the riser links them back to the main comms room. The same applies to a single large floor where some desks are too far from one rack.
Linking comms rooms. The main comms room, a server or data room, and a second rack serving a far wing are usually joined with fibre, often with more than one path if the business cannot afford a single cable cut.
Warehouses and large floors. Copper Ethernet stops at 100 metres, including patch leads. Large warehouses hit that limit quickly, so switches sit in several places along the building with fibre between them.
Campus and multi-building sites. Schools, aged-care sites, factories with a separate office, and yards with a gatehouse all need a link between buildings. Fibre cable with no metal in it does not create an electrical path between buildings, which a copper run between them does.
Bringing a carrier service to the rack. When the carrier’s fibre terminates on the ground floor or in a basement and the network lives upstairs, the business’s own cabling has to bridge the gap.
When does fibre beat copper or point-to-point wireless?
| Situation | Usually best | Why |
|---|---|---|
| Desk, access point and camera outlets | Cat6 or Cat6A copper | Cheaper, and it can carry power to the device |
| Link over 90 metres inside a building | Fibre | Copper runs out of distance |
| Backbone between floors or racks | Fibre | Distance and headroom for 10 Gbps and up |
| Building to building, cable path available | Fibre | Highest capacity, no weather or line-of-sight issues |
| Building to building, trench too costly | Point-to-point wireless | No civil works, installed in days |
| Short link between two racks in one room | Copper or fibre | Either works; follow the switch ports |
Copper still wins at the edge because it can carry power over Ethernet to access points, cameras and phones. Cat6 vs Cat6A covers that side.
Between buildings, the honest trade-off is cost and time. A trench, conduit and reinstatement across a car park can cost far more than the fibre inside it. Where a clear line of sight exists, point-to-point wireless is often the sensible answer. Where it does not, or where the link has to carry a lot of traffic for many years, fibre is worth the civil works.
Single-mode vs multimode fibre
Multimode fibre carries light along a wider core and uses lower-cost optics, but its reach falls as speed rises. Single-mode has a much narrower core and reaches kilometres at any speed a building network is likely to need.
| Fibre | 10 Gbps reach | 100 Gbps reach | Typical use |
|---|---|---|---|
| Multimode OM3 | About 300 m (10GBASE-SR) | About 70 m (100GBASE-SR4) | Short runs inside a building |
| Multimode OM4 | About 400 m (10GBASE-SR) | About 100 m (100GBASE-SR4) | In-building backbones, data rooms |
| Single-mode OS2 | Around 10 km (10GBASE-LR) | Around 10 km (100GBASE-LR4) | Risers, campus links, anything long-life |
Reach figures are from the IEEE Ethernet standards as published by the Ethernet Alliance and The Fiber Optic Association. Real designs also have to fit a loss budget, which connectors and splices eat into.
Our recommendation for most new work is single-mode. It removes distance as a future constraint, and the cable will outlast several generations of switches. Choose multimode where the run is short, the equipment at both ends already uses multimode optics, and matching the existing system is worth more than the extra reach.
Whichever you choose, the optics in the switches at each end have to match the fibre type and speed. Mixing multimode and single-mode on one link does not work.
Connectors, patch panels and enclosures
Fibre ends at a patch panel or enclosure in each rack, and patch leads run from there to the switch.
- LC duplex is the most common connector in business racks today. One fibre transmits and one receives.
- SC is older and larger, and still common in carrier equipment and older installs.
- MPO packs many fibres into one connector. It is used mainly in data rooms with high-density, pre-terminated trunks.
Order more fibre cores than today’s design needs. The labour and the pathway are most of the cost, and spare cores mean the next switch, camera network or second path does not need a new cable.
AS/CA S009, the Wiring Rules, has specific fibre requirements. Fibre panels and enclosures must carry laser warning labels, unused connectors and adaptors must be covered, and fibre cables must be identifiable so nobody mistakes them for power. Connector end-faces should be inspected with a proper scope and cleaned before connection, because dirt on the end-face is a common cause of fibre faults.
Fusion splicing or pre-terminated fibre?
There are three common ways to put connectors on building fibre.
Fusion-spliced pigtails. The cable is run, then each fibre is fusion spliced to a short factory-made lead with a connector on it, inside a splice tray in the enclosure. The Fiber Optic Association describes fusion splicing as the method with the lowest loss and least reflectance. It lets the cabler cut each cable to the exact length on site.
Splice-on connectors. Similar idea, with the connector itself fusion spliced onto the fibre. It suits jobs with a few terminations.
Pre-terminated assemblies. The cable arrives from the factory already fitted with connectors and tested. Installation is quick and needs no splicer, which suits data rooms and tight shutdown windows. The catch is that lengths must be measured exactly before ordering, and the pathway has to fit the connector ends and pulling grip.
Mechanical-splice field connectors exist too. They avoid a splicer but give higher losses, and are better left for repairs than for a new backbone.
All three methods give good results when done properly, and the test results tell you whether they were. For a riser or campus backbone, fusion splicing is the usual choice. For a dense data room, pre-terminated trunks often save time.
Indoor, outdoor and underground runs
Fibre comes in cable constructions for different places:
- Indoor cable for risers and ceiling space.
- Indoor/outdoor cable that can run from a comms room, through a wall and across a roof or into conduit without a joint at the building entry.
- Underground runs in conduit between buildings, often with a cable built to resist moisture and rodents.
Cable with no conductive parts is exempt from some of the Wiring Rules’ separation requirements, but it still has to be installed so nobody is exposed to electrical hazards. S009 notes that drawing fibre through electrical conduit may need a licensed electrical worker.
The cabler’s registration matters here. The ACMA lists optical fibre, structured, underground and aerial as separate competencies added to an Open registration. A trench between two buildings needs a cabler with both the optical-fibre and underground competencies. Who can install data cabling explains the registration types.
Testing fibre
Fibre should be tested before anyone signs off the job. There are two levels:
- Tier 1 measures the total light loss over each fibre, its length and its polarity, using a light source and power meter or an optical loss test set. This is the standard acceptance test.
- Tier 2 adds an OTDR trace, which shows the loss of each splice and connector along the link and where any fault sits. Fluke Networks notes that a link can pass a total loss test and still have a bad joint that only an OTDR reveals.
Tier 1 is the minimum for every fibre. Tier 2 is worth asking for on backbones, long campus runs and anything with splices, and some manufacturer warranty programs ask for it. Data cabling testing and certification covers what the test report should show.
Where your fibre stops and the carrier’s begins
The fibre an NBN or carrier service arrives on belongs to the carrier, right up to its network termination device. The ACMA says registered cablers cannot perform or supervise work on cabling owned by a carrier or NBN, and the Wiring Rules do not apply on the carrier’s side of the network boundary.
So a typical project has two parts:
- The carrier builds the lead-in and installs its termination device, usually in a ground-floor or basement comms room.
- Your cabler runs the building’s own fibre or copper from that point to the rack where your router and switches sit, and builds the backbone from there.
In a new building, someone also has to provide the pathway for the lead-in. Communications in a new commercial build covers who does that and when.
What to put in a fibre brief
A good fibre quote states:
- each link, from which rack to which rack, with approximate route and length
- fibre type (OS2, OM3 or OM4) and core count per cable
- indoor, indoor/outdoor or underground cable, and any conduit or trenching included
- termination method and connector type
- patch panels or enclosures at each end, and patch leads
- Tier 1 testing on every fibre, and Tier 2 OTDR testing where you want it
- labelling and an as-built record of the route
If the quote only says “fibre link, supply and install”, ask what is assumed. Trenching, core drilling and access through common property are the items that move the price.
Helpful starting points
Kookaburra Comms installs single-mode and multimode fibre between racks, floors and buildings as part of our data and fibre cabling work across Melbourne and Victoria, alongside the copper cabling and comms racks. For a warehouse or a site with several buildings, see warehouse and distribution networks. Send us the site plan and where each rack sits, and we will walk the route and quote each link.