This number starts with a 5, which is the Gas range. It is a valid NMI — the Checksum above is correct — but it identifies a Gas Connection, not an Electricity Connection. Gas numbers are called a MIRN, or a DPI in New South Wales and the ACT.

That contains a character which cannot appear in one of these numbers. The letters O and I are never used — they are too easily confused with the digits 0 and 1. Check those two.

Only the first 11 characters are used — the 10 digits plus the Checksum digit. Anything after that has been removed.

NMI Checksum Digit CalculatorNMI Checksum Digit Calculator