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Was the cable bitten by a rodent? The standard tells you how to recognise it, not how much it must withstand

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Gnarled tree roots breaking through the soil, close-up black-and-white photograph
Where a buried cable runs close to decaying roots, the standard flags the risk. How much the sheath must withstand, it does not say.

A buried cable stops transmitting at one precise point, well away from any joint or bend. Once the trench is opened, the sheath is neither crushed nor cleanly cut: it has an irregular hole, its edges chipped inward. Something attacked it from outside. Before even knowing which animal did it, the question that matters is another one: was that section, laid in that particular ground, ever protected against this? And if so, where is it written down?

A renumbered Recommendation, not a rewritten one

The Recommendation covering this is ITU-T L.161, a text from October 2000, still “in force”: the official ITU page states “Former ITU-T L.46 renumbered as ITU-T L.161 on 2016-02-15 without further modification and without being republished.” Same content as twenty-five years ago, different code on the cover.

The Scope is one line: “There is evidence that the outside of the plant can be damaged from biological attack.” Clause 2 lists the culprits as a bulleted set: “mammals, squirrels, mice, rats, moles, gophers and other rodents”, “birds like woodpeckers and cockatoos”, “insects such as termites, ants, beetles, wasps and caterpillars”, “micro-organisms like bacteria, fungus and/or moulds.” Four families of attacker, not just the rodent that comes to mind first.

A bite reads like a signature

The most operational part is Clause 3, which describes damage as a signature: “Vertical chiselling of incisors on the edge of irregular holes is typical of the damage caused by rodents”; moles, by contrast, leave smooth spherical holes. Termites and ants leave a different mark: “Irregular holes that may extend over the whole circumference, looking as though the sheath has been peeled off, are typical of termites and ants.” And they leave a chemical trace too: “Ants and termites can give off an acidic secretion that is corrosive to lead” — useful for telling them apart from a rodent even months later. Beetles and larvae bore circular holes; micro-organisms leave no hole at all, they degrade — cellulose fibres and elasticised polymers losing mechanical strength with nothing visible to show for it.

Countermeasures: where to route, what to seal, which sheath to choose

Clause 4 splits protection into four levers. The first is positioning: Table 1 lists risk environments — breeding grounds for insects, old trees harbouring olive beetles, rotting wood and larvae, decaying roots and termites, waterlogged ground and bacteria — best avoided at the design stage where possible. The second is chemical elimination of the pest, with an explicit warning to handle products according to their safety data sheets. The third is a physical barrier, Table 2: metal netting over the cable against squirrels, galvanised iron guards where the cable emerges from the ground and, a point that touches every handhole, “Tightening of fittings in junction boxes, blocking with epoxy resin casting in small boxes” against ants, insects and beetles — the tightness of splice closures is not only a matter of water.

The fourth lever is cable construction, Table 3: steel wire, fibreglass or aramid armouring against squirrels and rodents; polyamide sheath against ants and termites; helical steel or brass tape against woodpeckers and termites alike. Two technical warnings apply: “Aluminium tape offers limited protection, especially thin foil (e.g. 0.1 mm) that is easy to penetrate” — and “Cables with steel armouring and/or dielectrical armouring such as fibreglass do not suffer any damage of this type as long as the armour is intact” — the armour protects only while it stays intact; a poor splice breaks that continuity, and the risk it was meant to exclude returns.

Italy is already in a table, in the appendix

Appendix II gathers national experience — illustrative material, not prescriptive — from several countries. For Italy there is a single row, Table II.2: location D (duct cables), all season, cause mammals, “Rats”, damage “Bite”, period “1993 to 1995”, countermeasure “None”. A rodent bite recurring for two years, with no countermeasure on record. It is the same blank box that ITU-T L.101 leaves written as “as agreed, see 6.4” for resistance to rodents and insects: that Recommendation sets a figure for crush and impact, and defers to this one — L.161 — for the rest. Read together, the two say the same thing from opposite sides: one identifies the attack, the other asks for a threshold. Neither writes it for you.

The data sits in six places, not one

Whoever has to answer yes, it was protected, and here is how rarely manages it with a single document:

  1. The technical datasheet of the cable actually laid — sheath and armouring type declared, often filed with the product records, not the network ones.
  2. The installation design and the as-built record — what environment the route actually runs through: near roots, on farmland, in a flood-prone area.
  3. The acceptance test report — measures crush and impact under L.101, not a biological attack: no test covers that.
  4. Records of splice closures and handhole openings — sealing and tightness at every entry point, the real barrier against insects.
  5. The maintenance log — reports of past bites or burrows on the same route, when anyone bothered to write them down.
  6. The contract, with the cable supplier or with whoever keeps the network running — the written agreement L.101 asks for on rodents and insects, often never signed.

What to put in the specification.

  1. Installation environment classified in writing, following the categories in Table 1/L.161 — not a generic “buried”.
  2. Armouring and sheath type declared by name, consistent with the classified risk — not left to the supplier’s catalogue.
  3. Physical barriers specified where they are needed: netting, guards, closure sealing — a line of its own, not implied by “IP68”.
  4. A written agreement on rodents and insects, as required by Clause 6.4 of L.101, with an agreed verification method — not a reference that defers yet again.
  5. A biological-event log per route, updated at every intervention, not only after the first fault.

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What we don’t know

Unlike L.101, ITU-T L.161 does not contain the explicit statement on the voluntary nature of compliance: we did not find it in this text, and we do not claim it is absent elsewhere in the ITU-T corpus. Neither appendix carries the wording “does not form an integral part of this Recommendation” found in more recent Recommendations of the same series: we still treat them as descriptive material, for consistency with the L-series’ practice. We neither assert nor rule out the existence of an Italian obligation on rodent protection for buried networks: we have not verified this against an Italian primary source.

The two axes, on this topic

First axis: the classified installation environment, the declared armouring and the written agreement on rodents and insects become specification lines with an owner and a date — and acceptance checks that the document exists, not that someone promised it verbally.

Second axis: the cable datasheet, the as-built record, the acceptance report, the splice-closure opening records and the maintenance log stop being separate files and become, with CSIDIA, the group’s other company, a single map of the network. On a biological attack that leaves no surface trace, the useful diagnosis is the comparison between successive reports tied to the same route identifier: one bite is an event; three bites at the same point over three years mean the environment should have been classified differently. An AI produces the diagnosis from that comparison, the crew closes the fault — within the client’s perimeter, on-premises on self-contained machines or dedicated cloud with a data centre in Italy, always with shared management.

From the site survey, at no cost, comes the list of your buried routes with, for each one, the classified environment, the armouring type, any written agreement on rodents and insects, and where it is recorded — including the boxes left blank, starting with that bitten section you already have in mind: who decided on its protection, and with what evidence?

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