Paul Rose's job as an electrical engineer with Mighty River Power (MRP) made him responsible for buying parts and organising services.
During his tenure, the Serious Fraud Office said, he set up companies that acted as a vendor to his employer. Although his employee agreement required him to disclose his conflict of interest, he did not.
Rose, described by colleagues as highly knowledgeable and the "go-to guy" at the Southdown power station, would buy goods from a real company, add a mark-up and sell them to MRP, the SFO said.
Although the father-of-four was convicted of obtaining $2.2 million by deception, this does not represent the financial harm suffered by MRP nor the benefit the Roses received.
Justice Rebecca Edwards said yesterday that she could not be satisfied beyond reasonable doubt that MRP had suffered direct financial loss of more than $60,000.
She could not be sure that MRP would not have made the same payments to third-party suppliers for the goods and services provided.
"This does not mean that Mighty River Power has not suffered loss beyond this sum. It may be able to prove substantial losses as a result of your deceit in civil proceedings. It is, of course, free to pursue that course if it so wishes," she said.
Although the Crown had asked for a reparation order Justice Edwards did not make one, saying MRP had other avenues to recover any losses.
The police, who have frozen the couple's assets, are also likely to apply to have them forfeited to the Crown following the pair's convictions.
Regardless of any financial harm, the judge said the Roses' actions had impacted the employees and reputation of the now-listed firm.
One manager who provided a victim impact statement to the court said the fraud put all work achieved at MRP during that time into disrepute.
For the purposes of sentencing, Justice Edwards put the benefit obtained by the pair at $618,000.
Drawings from one of the companies funded the former couple's lifestyle and were used to pay the deposit on a house.
Justice Edwards said Paul Rose shared in "ill-gotten gains" from his offending, which she described as premeditated and sophisticated.
"The motivation for your offending, Mr Rose, was greed," the judge said. "Your offending also involved a breach of the trust reposed in you by family and friends. You involved your mother in the deceit by asking her to become a director.
"A sentence of imprisonment is the only appropriate response for the gravity of your offending."
When sentencing Jane Rose, Justice Edwards said she played a secondary role in the offending and owed no legal duty to MRP.
"You were not in a position of trust and confidence," the judge told the single mother-of-three.
However, Justice Edwards said the offending gave Jane Rose a lifestyle she could not have enjoyed if she had not assisted her then-husband with his deception of MRP.
While the Crown wanted Jane Rose to be sent to jail, the judge said home detention was appropriate.