The NCA will instead lay new high-voltage cabling, racking up at least $30,000 extra in the $2.7 million repair job.

Mr Snow said the old cabling will remain buried on the advice of asbestos specialists.

"The condition of the cable was a concern to us and we made the decision that if we did not want to have the possibility of problems in the future the most cost-effective solution was to replace the cable completely," Mr Snow said.

"We'll leave it in the ground [upon] specialist advice and we will be replacing the high voltage cable that connects the substation to the pump house with brand new cables."

The discovery that bonded asbestos coated the old cabling was the latest in a string of problems that have caused the jet to lay dormant since June last year.

Compounding their latest headache, the NCA found the substation transformer was not compatible with the new equipment and was below modern Australian standards.

Workers extracted the old switchboard and lowered in a new electrical substation into the pump station at Regatta Point on Monday.

"Again Australian standards have changed since the substation and pump house were built back in the 60s so we want to make sure these works will mean there'll not only be greater reliability of this important asset but that we can also make sure that the jet operates for another 25 years as it was always intended to," Mr Snow said.

Mr Snow said these recent issues would not blow out the budget or timeline for the upgrade of the city's signature water spurt.

He said they expect to turn the jet back on in the second half of the year as planned.

"For the project we did provide a contingency for things we might encounter. The cabling works, the new substation transformer, these have all been factored into the project budget and we expect the cost associated with those will be well within budget and we will stay on track with our estimated competition cost," Mr Snow said.