An incompetent heating engineer, with no gas qualifications, could face jail, The Northern Echo has reported.
Mr Keith Downie, who traded as a heating engineer under the name All Systems in the Darlington area, gave the details of other, qualified plumbers on safety certificates.
Officials fear Mr Downie may have carried out substandard work on other gas appliances in homes around Darlington and have urged anyone who has concerns to contact the Gas Safe Register.
According to court documents, people living in three properties where evidence of Mr Downie’s work on gas appliances was found were put at risk of carbon monoxide poisoning, fire and explosions.
In a prosecution brought by the Health and Safety Executive, Mr Downie, 51, of The Firs, Darlington, pleaded guilty to six charges of contravening a health and safety regulation.
Darlington Magistrates’ Court heard that Mr Downie had no training to work on gas appliances and had never registered on the Gas Safe Register, which all gas engineers must legally sign up to.