When a buried cable fails, the fault location crew arrives with instruments, but the cause list is short and familiar. Roughly in order of guilt:
Somebody dug. Excavation damage is the leading killer of underground cable everywhere, and India’s road-widening decade has not helped. Sometimes the strike is instant and obvious. Just as often the digger nicks the sheath, nobody reports it, and the cable fails months later once water finds the wound. Route markers, warning tiles above the cable and accurate route drawings are boring — and cheaper than everything else on this page.
A joint let go. Joints concentrate everything that can go wrong: field workmanship, moisture sealing, conductor connection. A joint made wet, made hurried, or made with a kit that nearly matched the cable is a fault with a delay timer. Fewer joints, better joints.
Water got in. Through a damaged sheath, an unsealed end left open before laying, or a tired joint. Moisture against insulation degrades it gradually — the cable keeps working while getting weaker, then fails on a day of high load or switching. Water-blocked constructions exist precisely to slow this story down.
It ran hotter than anyone admitted. Overload, ground that holds heat, cables grouped tighter than the design assumed, or a rating that was read off the datasheet without applying site conditions. Heat is cumulative insulation damage. Where sustained load growth is the reality, conductors sized with honest margins — or constructions rated for higher operating temperature, like 105 °C high-ampacity XLPE — are the grown-up answer, not hope.
Laying day came back to collect. Dropped drums, tight bends, cable dragged over stone, missing bedding. None of it shows on commissioning tests; all of it shortens life. Armour buys real protection against mechanical abuse — the armouring guide covers the choices — but armour is a seatbelt, not immunity.
Something chewed. Rodents and termites attack sheaths in ducts and loose soil. Where the local wildlife has a record, say so at enquiry stage — constructions exist for it.
The pattern across the whole list: faults are usually bought early — in trench discipline, joint count and sizing honesty — and paid for later, with interest, at three in the morning.