A sky rail tradesman who stole more than $100,000 worth of copper from the taxpayer-funded project as part of an organised racket has been jailed for six months.

New Zealand-born Hayden Tarawa, the first to be jailed over the thefts, was also slapped with a two-year community corrections order after pleading guilty to stealing nearly 4500 kilograms of copper from the $1.6 billion Caulfield-to-Dandenong sky rail project.

Building supervisor Kory Oxley (left) and tradesman Hayden Tarawa. Credit:Joe Armao and Luis Ascui

The sentence came as the judge noted that tradesmen who refused to steal huge spools of copper were called "poisonous rats", had their livelihoods threatened and were singled out for abuse on the job site.

Tarawa's boss, former Lendlease building supervisor Kory Oxley, earlier pleaded guilty to falsifying time sheets on the sky rail project.