The house bus was then sold on Trade Me, but a subsequent electrical inspector described the work as "incompetent and extremely dangerous" and noted there was a risk of injury to people using the bus.
The bus chassis was not earthed and there was also incorrect polarity to the power points.
Koridon admitted he had done the work, but said he didn't charge for labour and that he did not realise this kind of work had to be carried out by a registered electrician.
New legislation brought in last month now requires all electricians carrying out prescribed electrical work to provide a compliance certificate or an electrical safety certificate to customers. The prosecution was one of four - with cases in Thames, Wellington and Porirua contributing to a total fine of $16,000.
Chief executive of the Electrical Contractors Association of New Zealand Neville Simpson said it was crucial for homeowners to check for certification from anyone doing electrical work for them.
"Apart from the safety aspects, homeowners could also face problems insuring or selling properties if they do not obtain certification for electrical installation work," Mr Simpson said.