Fibre Optic Cabling Guide: OM1 to OM4, Connector Types, Cable Construction & Why Fibre Beats Copper

As businesses continue to demand faster networks, higher bandwidth, and greater reliability, fibre optic cabling has become the preferred choice for modern network infrastructure. Whether you're connecting network cabinets, linking buildings, supporting WiFi deployments, or preparing for future growth, selecting the right fibre cable is essential.

At Morecom Ltd, we design and install fibre optic infrastructure for commercial, industrial, educational, and public sector environments, helping customers choose the right cable specification for both current and future network requirements.

What is Fibre Optic Cabling?

Unlike traditional copper cabling that transmits electrical signals, fibre optic cable uses pulses of light to transmit data through glass fibres. This allows significantly higher speeds, longer transmission distances, and improved reliability.

Common fibre applications include:

• Core network links
• Server room interconnects
• Building-to-building connectivity
• CCTV backbones
• WiFi infrastructure
• Data centre networks
• Industrial networking

Understanding OM1, OM2, OM3 and OM4 Fibre

Multi-mode fibre is classified into several categories, with each offering different speed and distance capabilities.

OM1 Fibre

OM1 fibre uses a larger 62.5-micron core and is typically identified by its orange outer jacket.

Typical capabilities

• 1Gbps up to 275 metres
• 10Gbps up to 33 metres

Best suited for

• Legacy installations
• Small networks
• Existing infrastructure upgrades

Today, OM1 is largely considered obsolete for new installations due to its limited bandwidth capabilities.

OM2 Fibre

OM2 uses a 50-micron core and also typically features an orange sheath.

Typical capabilities

• 1Gbps up to 550 metres
• 10Gbps up to 82 metres

Best suited for

• Older commercial networks
• Basic backbone links

While an improvement over OM1, OM2 is rarely specified for modern installations.

OM3 Fibre

OM3 fibre is laser-optimised and typically uses an aqua-coloured sheath.

Typical capabilities

• 10Gbps up to 300 metres
• 40Gbps up to 100 metres
• 100Gbps up to 100 metres

Best suited for

• Business networks
• Data centres
• School campuses
• Modern office installations

OM3 remains one of the most commonly deployed fibres today.

OM4 Fibre

OM4 is an enhanced version of OM3 that supports longer distances and higher performance.

Typical capabilities

• 10Gbps up to 550 metres
• 40Gbps up to 150 metres
• 100Gbps up to 150 metres

Best suited for

• Enterprise networks
• High-performance computing
• Data centres
• Future-proof installations

OM4 is typically the preferred choice when businesses want a network infrastructure that can accommodate future speed requirements without replacing cabling.

Quick Comparison

OM1
Core Size: 62.5
10GB Distance: 33m
Uses: Legacy

OM2
Core Size: 50
10GB Distance: 82m
Uses: Older Business Networks

OM3
Core Size: 50
10GB Distance: 300m
Uses: Modern Commercial Networks

OM4
Core Size: 50
10GB Distance: 550m
Uses: Enterprise & Future Proofing

Morecom Recommendation

For almost all new installations:

✅ OM3 for standard commercial projects

✅ OM4 for long-term future-proofing

Fibre Connector Types Explained

The connector is as important as the cable itself.

LC to LC

LC connectors are currently the most widely used connector in modern networking equipment.

Benefits

• Small form factor
• High-density patching
• Data centre standard
• Common on SFP and SFP+ modules

Best used for

• Network switches
• Servers
• Modern patch panels

LC-LC is now the most common configuration for business fibre installations.

LC to SC

SC connectors are larger and were widely used before LC became popular.

Benefits

• Robust design
• Easy installation
• Common on older fibre infrastructure

Best used for

• Legacy equipment integration
• Mixed infrastructure environments

An LC-SC patch lead is often used when connecting new equipment to older fibre cabinets.

SC to SC

SC connectors remain common in older installations and telecoms environments.

Benefits

• Durable
• Easy to terminate
• Cost-effective

Best suited for

• Existing infrastructure
• Legacy network equipment

Which Connector Should You Choose?

Choose LC-LC if:

✅ Installing new fibre infrastructure

✅ Using modern switches

✅ Deploying 10Gb, 25Gb or 100Gb networking

Choose LC-SC if:

✅ Connecting new equipment to older networks

Choose SC-SC if:

✅ Maintaining an existing SC-based installation

Loose Tube vs Tight Buffered Fibre

Another important consideration is cable construction.

Tight Buffered Fibre

Tight buffered fibre surrounds each fibre strand with additional protective material.

Benefits

• Easier to handle
• Simpler termination
• Better for indoor environments
• More flexible

Best applications

• Office buildings
• Comms rooms
• Internal risers
• Structured cabling

Most internal fibre installations use tight buffered cabling.

Loose Tube Fibre

Loose tube fibre protects the fibres inside water-resistant tubes.

Benefits

• Better environmental protection
• Excellent moisture resistance
• Reduced strain on fibres
• Suitable for longer distances

Best applications

• External installations
• Underground ducts
• Campus links
• Building-to-building connections

Loose tube fibre is generally preferred for outdoor work.

Why Fibre is Better Than Cat5e and Cat6

Although Cat5e and Cat6 remain popular for desktop connectivity, fibre offers several significant advantages.

Distance

Cat5e

• Maximum 100 metres

Cat6

• Maximum 100 metres

Fibre

• Hundreds of metres to several kilometres

This makes fibre ideal for connecting separate buildings or large sites.

Speed

Cat5e

• Up to 1Gbps

Cat6

• Up to 10Gbps (short distances)

Fibre

• 10Gbps
• 25Gbps
• 40Gbps
• 100Gbps+
• Future upgrades possible without removing cabling

Electromagnetic Immunity

Copper cabling can be affected by:

• Electrical interference
• Machinery
• Power cables
• Lightning

Fibre is completely immune to electromagnetic interference.

This makes it ideal for:

• Factories
• Warehouses
• Industrial sites
• External installations

Security

Unlike copper cabling, fibre does not radiate electrical signals.

Benefits include:

• More secure transmissions
• Difficult to intercept
• Reduced risk of data leakage

Future-Proofing

A correctly installed OM4 fibre backbone can support multiple generations of networking technology without replacing the cable itself.

While switches and transceivers may change, the fibre infrastructure often remains in service for decades.

Which Fibre Should Your Business Install?

For most businesses, Morecom Ltd recommends:

Internal Building Links

• OM3 or OM4
• LC-LC connectivity
• Tight buffered construction

Building-to-Building Links

• OM4 multi-mode or single-mode
• Loose tube cable
• Armoured protection where required

Data Centres & High-Speed Networks

• OM4 fibre
• LC-LC patching
• Structured fibre management

Conclusion

Choosing the correct fibre optic infrastructure is one of the most important decisions in any network deployment. While OM1 and OM2 still exist in legacy environments, OM3 and especially OM4 provide the performance, scalability, and future-proofing required by modern organisations.

Combined with the correct connector type, cable construction, and professional installation, fibre optic cabling delivers superior speed, reliability, security, and longevity compared to traditional Cat5e and Cat6 cabling.

Morecom Ltd provides complete fibre optic solutions including design, installation, testing, fusion splicing, fibre certification, and ongoing support, helping businesses build network infrastructure that is ready for today's demands and tomorrow's growth.