The Federal Energy Regulatory Commission on Thursday conditionally approved rate incentives for a $1.4 billion transmission project in Maine that will increase reliability and capacity to export power to southern New England.

According to a news release issued by the federal agency, FERC granted Central Maine Power Co.’s petition for transmission incentives for its Maine Power Reliability Program Project. The approval, however, is subject to the condition that ISO-New England include the project in its regional system plan as a reliability transmission upgrade.

FERC noted that the planned project is the largest project in CMP’s history and, when completed, will give the electric utility an estimated $1.85 billion of transmission infrastructure in service — six times more than the company’s current transmission capabilities.

The proposed upgrade consists of 245 miles of new 345-kilovolt transmission line and 74 miles of new 115-kilovolt transmission line, 10 miles of rebuilt 345-kilovolt transmission line and 155 miles of rebuilt 115-kilovolt transmission line and additional improvements.

A fact sheet about the proposed upgrade states that the new transmission infrastructure will include the new 345-kilovolt line running from Orrington to Portsmouth, N.H.

FERC granted CMP a 1.25 percent return of equity, or ROE, rather than the 1.5 percent the utility requested, and conditioned CMP’s proposal to recover 100 percent of construction-work-in-progress, or CWIP, in rate base on CMP’s including it in a future rate filing.

FERC also granted CMP’s request for recovery of 100 percent of “prudently incurred” costs associated with abandonment of existing infrastructure, provided the abandonment is a result of factors beyond its control.

FERC determined that CMP has shown that the total package of incentives addresses the risks and challenges faced by the project. The ROE incentive, CWIP and abandonment will encourage investors despite the project’s risks, according to FERC.