The owner of a faulty electricity interconnector has said the Northern Ireland electricity consumer is not expected to shoulder direct costs for its repair.
One of two cables which make up the Moyle electricity interconnector, joining the electricity systems of Northern Ireland and Scotland, has been broken since June.
A spokesman for Mutual Energy, which owns the interconnector, said: "Testing is ongoing to establish the precise fault location and an associated detailed repair plan is being developed.
"Given the nature of working offshore in water depths of up to 140m a typical repair schedule for this type of fault could be in the region of six months.
"The direct cost of the repair is not yet known but Moyle has insurance in place to cover these type of events so the Northern Ireland electricity consumer should not bear the direct costs for the repair."
Economist John Simpson said the absence of half of the link could be critical.
He said the electricity industry in Northern Ireland needed access to supplies crossing the North Channel from Scotland and cross-border flows.
"The market advantage works both ways. In some market conditions, Northern Ireland's system supplies the other areas.
"More important recently is the value of importing electricity from the Great Britain grid using the Moyle interconnector."
He said the fault had happened at a time when the interconnector was being used "heavily" for Northern Ireland supply.
"During the last year, wholesale electricity prices in Great Britain have been cheaper than those in Northern Ireland which has produced a consistently high level of contract capacity booking for the cross-channel flow.
"While Northern Ireland has sufficient electricity generating capacity to meet normal needs, including those from the benefits of the all-island Single Electricity Market, the absence of half of the Scottish link could be critical if there was any significant, even temporary, loss of local generating capacity."
Mutual Energy also owns the natural-gas pipeline from Scotland to Ballylumford and the natural-gas transmission pipelines to Belfast from Ballylumford.
Power NI - the new name for NIE Energy - is expected to confirm a 17% to 20% rise in prices this week.