This generator was new, documented and ready to install. At first glance, the connection point also looked right: red to red, white to white, blue to blue and black to black.
The problem was behind the labels. The blue phase conductor terminated on the breaker's neutral through-stud, while the neutral position had been identified as a phase. The site electricians had followed the supplied markings exactly.
We found the error during final testing after the generator was connected and the breaker cover was removed. That is the reason commissioning includes physical verification; a neat installation and correct-looking labels do not prove the conductors are in the right place.
In an Australian MEN installation, neutral and earth are linked at the main switchboard to provide a fault path. Putting an active phase into the neutral position can create a serious phase-to-earth fault when the generator supply is made live. Depending on the switching arrangement, the result may include high fault current, arcing, damaged switchgear, an extended outage or energised bonded metalwork.
The generator could still start, run smoothly and display normal voltage. None of that would have shown that the outgoing connection was unsafe. Polarity, phase rotation, conductor identification, protection and the transfer arrangement all had to be checked at the actual points of connection.
The fault was corrected before the generator entered service. No equipment was damaged and nobody was exposed to the consequences of an incorrect connection.
The takeaway is uncomplicated: test the installation in front of you. Do not assume the factory labels, drawings or cable colours are right just because they agree with each other. Permanent generator connections and changeover systems must be installed and verified by licensed electricians to the applicable Australian requirements, including AS/NZS 3000 and AS/NZS 3010.