PILC cable — recognising paper-insulated, lead-covered cable still buried in the ground

The guide on mineral-insulated (MICC) fire-resistant cable covers a different technology that shares one important theme with this article: an insulation system that depends entirely on an intact outer sheath to keep moisture out. This article covers PILC cable — paper-insulated, lead-covered — the technology that dominated medium- and low-voltage underground distribution in the Netherlands for most of the 20th century, before XLPE cable progressively took over from roughly the 1970s-80s onward. A large amount of PILC cable remains buried and in service today, so recognising it on sight matters well beyond historical interest.

Recognising PILC cable

PILC cable has a distinctive look and feel that sets it apart from modern plastic-sheathed cable:

A continuous, soft grey lead sheath directly over the insulated cores — lead is soft enough that firm thumb pressure leaves a visible dent, which plastic-sheathed cable never does.
Noticeably heavier per metre than a plastic cable of comparable conductor size, because of the lead sheath's mass.
Often a jute (fibrous) serving wound over the lead sheath as mechanical and corrosion protection, rather than the smooth extruded plastic outer sheath of modern cable.
No coloured, extruded plastic outer sheath with printed manufacturer markings of the kind used on modern XLPE or PVC cable — the surface is dull grey lead, sometimes coated in bituminous compound, rather than black or another moulded plastic colour.

Why the insulation depends entirely on the lead sheath staying intact

PILC cable's insulation is paper, impregnated with an insulating oil or compound. Paper of this kind is hygroscopic — it readily absorbs moisture — so its insulating performance depends entirely on the lead sheath remaining unbroken over the cable's entire service life. Where the sheath is breached (by corrosion, mechanical damage, or a poorly executed joint), two things typically happen together: moisture ingress degrades the paper insulation at that point, and the impregnating oil can migrate out through the same breach — an environmental as well as an electrical concern. This is the same hygroscopic-insulation theme covered for MICC cable's mineral (MgO) insulation in the related guide, though the specific degradation mechanism and consequence differ.

Hazard: lead exposure when cutting, grinding or reworking

Working on PILC cable — cutting it, stripping the sheath, or grinding during a repair — can generate lead dust or fume, a recognised health hazard requiring appropriate personal protective equipment and hygiene measures (avoiding inhalation and ingestion, controlled disposal of waste and swarf) rather than being treated as routine metal cable-sheath work. This is a hazard specific to PILC's lead sheath that has no equivalent in plastic-sheathed modern cable.

Age is not a reason to skip precautions before digging

A PILC cable's age and outward appearance of disuse are never grounds to assume it is dead or unimportant: many PILC circuits remain in active service, and even a decommissioned one may still be present and physically hazardous to strike with excavation equipment. The same KLIC/graafmelding excavation-notification precautions that apply to any underground cable apply in full to ground where PILC cable may be present — see the guide on the KLIC/graafmelding excavation- notification obligation — and cable-locating and hand-digging precautions near a located cable route are not relaxed just because the cable looks old.

Termination and jointing: not compatible with standard push-fit or crimp joints

A PILC cable cannot simply be terminated or jointed with the push-fit, crimp, or heat-shrink connectors used on modern XLPE or PVC cable. Joining or terminating PILC cable — or transitioning it to a modern XLPE cable, which is common when a PILC section is being partially replaced — requires a specialist lead-wiped joint (where a skilled jointer wipes molten lead to re-form a continuous sheath around the joint) or a purpose-made resin- or heat-shrink transition joint specifically designed to seal against a lead sheath and bridge to a plastic-sheathed cable. Attempting a standard low-voltage joint kit intended for plastic-sheathed cable on a PILC sheath will not achieve the moisture-tight seal the paper insulation depends on.

Practical relevance

When excavation, cable identification (see also the guide on cable identification — markings, ferrules and nameplates), or repair work encounters an old underground cable, it should be checked for the recognisable features of PILC — a soft lead sheath, jute serving, notable weight — before assuming it is a modern plastic-sheathed cable; that any breach of the lead sheath is treated as a moisture-ingress and oil-leakage risk needing prompt attention rather than a purely cosmetic issue; that cutting or grinding work is planned with lead-exposure controls in place; and that any joint or termination is made using a method actually designed for a lead sheath rather than a standard plastic-cable joint kit.

Common mistakes

Assuming an old, decommissioned-looking underground cable is safe to strike or cut without a KLIC check, purely on the basis of its age or apparent disuse.
Treating cutting or grinding work on a PILC sheath like ordinary metal cable-sheath work, without the lead-exposure controls (PPE, hygiene, controlled waste handling) the material requires.
Attempting a standard plastic-cable push-fit, crimp, or heat-shrink joint kit on a PILC sheath, which cannot achieve the moisture-tight seal the hygroscopic paper insulation depends on.
Ignoring a breached lead sheath as merely cosmetic, when it is in fact an active pathway for both moisture ingress into the paper insulation and oil leakage from it.