Fibre Optic Technician key topics and quick reference

Updated 17 September 2026 · 2 min read

A fibre technician needs certain facts instantly: which fibre goes where, what each connector is, what a wavelength implies for loss. The reference tables on this page hold them. The notes below explain how they connect when you plan, build and prove a real link.

How this guide was made

Written for this site with AI assistance, then checked automatically before publishing. The topic table, sample questions, worked examples and study plan are generated from this site’s question bank: each worked example is recalculated by separate code, and each sample answer says where it came from.

The guide deliberately states no salaries, grades, pass marks or exam dates. Those change, and they could not be checked here, so take them from the advert itself.

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Where to spend your study time

The suggested emphasis reflects what this position works with day to day. It is a study guide, not a published exam blueprint.

Area	Suggested emphasis	Questions in the bank	Practise
Fibre optics and cabling	63%	1,221	Fibre & Cabling
Networking fundamentals	25%	2,636	Networking
Maintenance practice	13%	1,784	Electrical

Fibre choice drives everything downstream

The fibre type decides the wavelengths, the equipment, the connectors and the reach. Choose or identify it first, because every later number depends on it. Single-mode for distance and backbone, multimode for shorter runs inside buildings and campuses where equipment cost matters more than reach.

Quick reference

Fibre optic basics

Item	Single-mode	Multimode
Core diameter	About 9 µm	50 µm (OM2 to OM5) or 62.5 µm (OM1)
Common wavelengths	1310 nm and 1550 nm	850 nm and 1300 nm
Typical reach	Kilometres to tens of kilometres	Hundreds of metres
Usual jacket colour	Yellow	Aqua (OM3/OM4), orange (OM1/OM2)
Connectors	LC, SC; APC variants are green	LC, SC, ST; MPO/MTP for multi-fibre

An OTDR locates events along a fibre - splices, connectors, bends and breaks - by distance. A light source and power meter measure the total end-to-end loss.

Common Ethernet cabling limits

Cable	Typical use	Distance
Cat5e	1 Gbps (1000BASE-T)	100 m
Cat6	1 Gbps; 10 Gbps over short runs	100 m at 1 Gbps; about 55 m at 10 Gbps
Cat6A	10 Gbps (10GBASE-T)	100 m
OM3 multimode fibre	10GBASE-SR	up to 300 m
OM4 multimode fibre	10GBASE-SR	up to 400 m
OS2 single-mode fibre	10GBASE-LR	up to 10 km

Connectors are where links fail

Most faults are at the ends. Know the common connector types on sight, know that angled and flat polished connectors must never be mated, and treat inspection and cleaning as part of every connection rather than a step for when something is wrong.

Adding it up

A link is a chain: fibre length times attenuation per kilometre, plus each mated connector pair, plus each splice. Learn the chain and the typical value for each element, and a budget question becomes a matter of care rather than recall.

Be able to explain in a sentence

The difference between single-mode and multimode fibre.
Why an APC connector must not be mated with a UPC one.
What an OTDR shows that a power meter cannot.
Why bend radius matters both during installation and afterwards.
What a reflective event in a trace usually means.

Common questions

How much of this must I memorise?

The fibre types, wavelengths, connector types and the structure of a loss budget. Specific standard values are supplied in tests and looked up in practice.

Do I need the cabling table if I work only on outside plant?

It is worth knowing. Outside plant meets structured cabling at the building entrance, and technicians are regularly asked about both sides of that boundary.