Emma Shaw died after being electrocuted at the West Bromwich flat she shared with her partner in December 2007. Miss Shaw, aged 22, was electrocuted while dealing with a leak from a boiler at her Jefferson Place flat, Grafton Road.
Prosecutors had alleged a form showed all of the electrical circuits had been signed off as 'problem-free' and a final signature was given by Neil Hoult, a qualified supervisor.
Investigations later revealed a circuit which fed an immersion heater in the boiler had been penetrated by a screw during the flat's construction.
The 53-year-old Hoult, from Dane Terrace, Rowley Regis, was found guilty by jurors last week of one charge of failure to discharge a duty under the Health and Safety at Work Act.
Today he was ordered to pay a £1,000 fine - the only penalty available under the Act.
Passing sentence, Judge Michael Dudley explained law set out he could only fix an amount the defendant could afford to pay within 12 months, which is why it 'may seem light'.
The judge told Hoult: "You have been convicted of a grave breach of duty. The testing of electrical circuits is absolutely vital. You were responsible for the failures in checking paperwork.
"Because of your failures and those of others who created this situation, you failed to detect a metal stud frame behind a plaster board at the house was live for a period of some 18 months.
"There was a leak in the boiler, the water soaked the carpet and that too became live and led to the inevitable death of Emma Shaw."
The judge said Hoult, who is no longer in the supervisory role, had to pay back the fine within 12 months or face 30 days imprisonment if he was in default.
The jury had deliberated for four hours and 35 minutes before finding him guilty.
Hoult's co-accused Christopher Tomkins, 52, from Rowley Village, Rowley Regis, was found not guilty earlier today after jurors deliberated for 11 hours 44 minutes.
Miss Shaw was found dead in a storage room by her partner Andrew Cross after he returned home from work to answer her frantic text messages about a pipe which had fallen off and saying 'the electrics were sparking' Her then 23-month-old son had been in the living room of the flat when she was electrocuted.
The court previously heard Tomkins and Hoult were both employed by Anchor Building and Electrical Services Ltd, which had been contracted to carry out electrical work during the development of Jefferson Place in 2006.