It is looking into whether the company failed to keep records of gas pipes – or risers – in some blocks of flats that are part of its network.
A riser is a gas pipe arrangement for a building which is more than two floors above ground level and has more than two meter points.
Formerly National Grid Gas Distribution, the firm owns, operates and maintains four of the eight gas distribution networks in the West Midlands, North West, East of England and North London and is responsible for keeping a record of those.
Ofgem is investigating if Cadent kept and maintained records for all of its gas pipes, whether it had the appropriate systems in place to do so and as a consequence, if it maintains an “efficient and economical” pipeline system.
It said the opening of the investigation “does not imply that we have made any findings about non-compliance”.
Cadent said the gas pipes in high rise buildings are made of steel and designed to have a lifespan of “several decades and are extremely robust”, with its surveys designed to puck up and address potential issues “many years before they occur”.
A spokesman added: “Between January and February 2018 Cadent identified that just some of our records regarding high-rise buildings – building of six storeys and above – were not contained on our digitised records and were therefore not part of our regular 10 yearly survey programme.
“As a consequence, we informed Ofgem at the earliest opportunity in early February and have continued regular progress briefings to date. Alongside this we immediately implemented a survey recovery programme to resolve the issue as quickly and effectively as possible. This programme of work will be substantially completed in July 2018.”