Certification

It is the Indian Standard covering rigid plain conduits made of insulating material — in practice, uPVC conduit for electrical wiring. It sets out the dimensions each nominal size must hold, and the mechanical, electrical and thermal tests the pipe has to pass in light, medium and heavy grades.

The mark is applied under a licence from the Bureau of Indian Standards. It means BIS has assessed the manufacturing process and tests the product against the standard on an ongoing basis — not that a single sample passed once. The licence number printed alongside the mark identifies the manufacturer holding it.

Every ISI-marked length of Dauphin conduit carries the licence number CM/L-9512401719 printed along the pipe, together with the size and grade. BIS maintains a public register of licences that can be searched by licence number, so anyone specifying or inspecting the material can confirm it independently.

Most government and institutional tenders, and a growing number of private specifications, require ISI-marked conduit by name. Unmarked pipe can fail inspection after the wiring is already run, which means opening walls. Buying marked material removes that risk at the point of purchase.