The company provided a market update on Tuesday morning, advising it was preparing to cut the cable.

Basslink chief executive Malcolm Eccles said he expected the cable to be operating by the end of May.

''In total, the repair teams have dedicated more than 30 days of round-the-clock fault location identification work due to the unexpected complexity of the fault,'' Mr Eccles said.

''While there remains some more days of work and analysis to be done before we can provide a more accurate estimate of return to service, it is an important milestone,'' he said.

Mr Eccles said the exact cause of the fault would not be known for some time and would require a detailed analysis of the damaged cable point before any conclusions would be reached.

''The probable fault location has been narrowed down to approximately 98 km from the Tasmanian coast,'' he said.

''Subject to weather conditions, it is anticipated that the cables will be cut within the next week.''

Dam levels are this week down to 15.5 per cent.

Manganese smelter Temco has announced it will make further energy reductions.

Hydro Tasmania is preparing to use 200MW of diesel generators to ease the state's energy woes.

Hydro is scaling down use at the Potatina station due to environmenteal concerns at Great Lake.