Preconnectorised fibre: what is there to certify when there are no splices?

Whoever signs off an FTTH run built entirely with preconnectorised components has not a single splice to certify: the columns of the acceptance report are there, the rows stay empty. And the terminal being accepted, by definition, cannot be reopened — at the first drop that fails to pass, it is replaced whole. What that replacement costs depends on two or three lines somebody wrote, or did not write, in the specification.

The Recommendation is from November, the PDF from April

On 29 November 2025 the ITU-T approved Recommendation L.405, Preconnectorized cabling components for FTTx infrastructures: edition 1.0, in force, twenty-six pages, a free PDF posted to the catalogue on 7 April 2026. We downloaded it and read it.

It defines preconnectorised components as “housings, closures, cable assemblies and terminals that are factory terminated with connectors”, and a note to the scope closes one door straight away: “This Recommendation does not describe patch-cords nor harnesses for indoor application”.

A terminal that is “not re-enterable” is not the manufacturer’s choice

In clause 3.2.13 a terminal is a “Protective housing that is not re-enterable”, factory terminated and intended to serve “typically between two and twelve” customer drops. It is not a product feature: it is the definition of the term.

Table 1 sets out the six configurations of the distribution area in columns, and the first row is “Re-entry”: yes only for the splice closure and for the preconnectorised closure with connectors; no for all three terminal variants and for the terminated distribution cable. The outputs, where they exist, are SC APC or LC APC — the angled family, never the flat one — and the tail-end input is MPO.

The table that contradicts half the specifications

Table 3 compares the three deployment methods: full-preconnectorised, semi-preconnectorised and fully spliced. On the row “Optimal installation type” the full-preconnectorised column carries two entries only, “Aerial, duct”: poles and duct. Direct burial appears in the other two columns alone. And on the row “Design and verification planning” it is the only method marked “High”.

The two things belong together. A preconnectorised drop reaches site already cut and terminated, and clause 6.2.3 asks the design to settle four parameters in advance: limiting the number of cables that run parallel to each other, standardising the capacity of terminals, determining the maximum length of drop cables, determining how many splitters sit in each distribution hub. The door-to-door survey is no optional extra: without it the bill of materials is an estimate, and the surplus lengths are paid for by whoever signed.

What gets measured, and where

End-face geometry is measured in the factory and cannot be corrected on site. Clause 7.4 sets the limits: cylindrical physically contacting ferrule, spherical radius between 5 and 30 mm, dome offset 50 µm maximum; angled ferrule, radius between 5 and 12 mm, the same dome offset, typical angle of 8 or 9 degrees; rectangular multifibre ferrule, eight parameters, from the x-angle to the adjacent fibre height differential. What is left in the field is end-face inspection and cleaning and the optical measurement of the link as a whole: there is no trace per splice, because there are no splices.

The loss and reflectance thresholds are not published by L.405. Clause 8.1 defers wholesale to IEC 61753-1:2018 — a paid standard: we report its title and edition from the catalogue, not its content — and clause 8.3 does no more than say which annex table applies to what. An asymmetry shows up there that is worth carrying into acceptance: for components the guidance covers categories C, OP, OP+ and I; for housings it covers C, OP, OP+, A, G and S. A hardened connector inside a flooded footway box — category G, “continuously immersed in water” — has no component table at all in that map. The seven categories and their environmental limits are given in full in Table 4: from C, −10 to +60 °C indoors, through to S, buried between 1 and 5 metres deep. And a note warns that the old category E remains “grandfathered”: “For permanent connections, categories A and G are recommended”.

Anyone after loss figures has to change Recommendation. ITU-T L.404 (08/2017), Field mountable single-mode optical fibre connectors, in force and likewise free, does publish them: attenuation grade Bf ≤ 0.35 dB mean and ≤ 0.55 dB maximum for more than 97 per cent of samples, grade Cf ≤ 0.4 and ≤ 0.75 dB; return loss grade 1 ≥ 60 dB mated and ≥ 55 dB unmated, grade 2 ≥ 45 dB, grade 3 ≥ 35 dB, grade 4 ≥ 26 dB; measurements at 1310 ± 30, 1550 ± 30 and 1625 ± 25 nm. But those grades apply to connectors mounted in the field: copying them into a preconnectorised supply while citing L.405 is a mistake that surfaces in a dispute.

Six lines for the acceptance report

The performance category, declared twice: once for the component and once for the housing that contains it, with the physical location that justifies it and the HD suffix wherever active electronics inside generate heat.
Re-enterable or not, sealed or free breathing, for every closure and every terminal, with the number of spare terminals held in stock and whose name they are held in: that is what separates a fault from an outage.
Connector type and end-face at every interface: SC APC or LC APC on the output, MPO at the tail end, mechanical intermateability with the connectors of ITU-T L.402 through an adapter or a convertor.
Port identification: “Ports should be distinguished by different colours and identified by serial number”. Colour and serial number belong in the as-built record port by port; where the enclosure is wall- or pole-mounted, the ports sit on its lower side.
The guide key: clause 8.4 calls for a key, and where the key is not visible for a mark showing the mating orientation. In the report that is a tick box, not a turn of phrase.
The mating and unmating check, which clause 6.2.4 wants for the drop “without tools and twisting operation”. If pliers are needed, it is a non-conformity.

What we do not know

IEC 61753-1:2018 is a paid standard and we have not read it: for the asymmetry between components and housings we report the guidance of clause 8.3, not the annex tables themselves, and we cannot rule out that a component table for categories A, G and S exists all the same. L.405 is a first edition with no corrigendum: Table 3 is headed “FTTC deployment summary and comparison” while the document is about FTTx, and we report it as printed. We do not know how many Italian specifications cite it already. And a compliant terminal is not a suitable terminal: compliance is declared by the supplier, suitability for the footway box is decided by whoever designs the network.

The point

Preconnectorisation does not take work away from acceptance testing: it moves it. The trace per splice disappears and a chain of declarations appears in its place — category, re-enterability, connector, port, key — to be checked while the lorry is still on site, because after the seal there is no going back. As with the sealing of closures: the declared environment counts for more than the catalogue code.

For an operator or a network contractor we do this on both sides. The six lines above go into the specification as clauses and come back at acceptance as checks of our own, with optical measurements and as-built documentation handed over together with the run. And with CSIDIA, the other company in the group, port serial numbers, declared categories, measurements and alarms become a single map of the network: when a drop goes down, an AI says which terminal is involved, whether it can be reopened and whether a spare is in stock, and a crew closes the fault — inside the customer perimeter, on-premises or in a dedicated cloud with data centres in Italy. Our own crews, no subcontracting.

Do you have a preconnectorised run to accept, or a specification to write for one that has yet to start? Talk to an engineer: the site visit is free of charge, and the category of a terminal is settled before the order, not in front of an open footway box.