A Christchurch drainlayer convicted of scamming earthquake victims out of thousands of dollars is now plying his trade in Wellington, prompting a warning to homeowners.

Alligator Drainage Director Graham Lilley was this week sentenced to 10 months home detention on 21 charges of obtaining by deception.

Lilley deceived by doing repairs on properties and falsely promising customers they would be fully reimbursed by EQC.

He is now working for the Wellington company Drain Master Limited, but is not licensed to do restricted work.

The Plumbers, Gasfitters and Drainlayers Board's Martin Sawyers said people need to be wary.

"Regardless of who comes to your property to do the work, you should ask them to show their authorisation card, and if they don't have an authorisation card, you simply shouldn't be allowing them to do the work on your property," Mr Sawyers said.

"We're currently investigating three instances where formal complaints laid with us involving Drain Master and some of it's employees, including Mr Lilley."

If charged and convicted, Lilley could be fined up to $10,000.