National Grid begins massive project to upgrade lines in Central Mass.

Ratepayers in the six New England states will pay for $474 million in electricity upgrades, and most of the work will take place in several Central Massachusetts communities.

National Grid’s application to modernize the Massachusetts portion of the aging A1/B2 transmission line that dates back to 1909 received the green light earlier this month from the Massachusetts Energy Facilities Siting Board.

The project cost was approved by ISO-New England for so-called regional recovery which means electricity customers across New England will foot the bill for the entire $474 million price tag since it’s a regional project.

The Massachusetts portion of the construction costs will be $414 million.

“The New England electric grid is a tightly interconnected system,” said an email from ISO-New England. “Therefore, costs for needed transmission projects are shared by consumers across the region, on the principle that all consumers benefit when the reliability of the regional network is improved. Because this project qualifies for regional funding costs are spread across the six New England states.”

It’s unclear when electricity bills will increase and by how much. The siting board’s approval noted final costs and allocation will be based on National Grid’s actual expenses on the project. Work is expected to start this summer and wrap up in 2030, according to National Grid.

Work on the 47-mile stretch of the line in Massachusetts will take place in Warwick, in Franklin County, and the northern Worcester County communities of Royalston, Athol, Winchendon, Gardner, Westminster, Fitchburg, Leominster and Sterling.

Improvements are complete on the roughly seven miles of the line that extends into New Hampshire and Vermont.

Some preliminary work is likely to occur later this week in the Gardner area and may involve tree clearing, according to National Grid. Roughly 130 acres of trees will be removed along the transmission line in Massachusetts.

The siting board’s approval emphasized all regulatory requirements including environmental have been met by National Grid.

Improving energy reliability is the project’s goal.

The siting board’s approval stated A1/B2 has some of the oldest transmission lines in New England. Parts of the line were worked on in the 1920s and 2004, but there have been numerous power failures in recent years due to an outdated design that is susceptible to damage from lightning strikes and birds that collide with equipment.

A noticeable change will be replacing 575 lattice towers with new monopoles. The current towers date back to when the line was originally built in the early 20th century.

ISO-New England projects regional electricity demand will increase by approximately 9% over the next decade, according to National Grid. Massachusetts is expected to lead that growth and the utility believes it’s time to modernize the line.

“National Grid is committed to delivering safe and reliable energy to our customers around the clock, and the A1/B2 project is a critical investment in that commitment,” said Lisa Wieland, president of National Grid New England. “Modernizing this infrastructure will strengthen day-to-day reliability, support economic activity, and ensure the system has the capacity and flexibility to meet growing energy needs.”

The new transmission lines are expected to operate by late 2030, initially providing 69 kilovolts of power with the capability to support 115 kilovolts, a range that National Grid says is the modern standard for transmission equipment.

No disruptions in power are anticipated during construction, the utility said.

A1/B2 was originally built to bring Vermont hydropower to towns in northern Franklin and Worcester counties, and National Grid said the line supported construction of tunnels that expanded the water supply to Boston.

Contact Henry Schwan at henry.schwan@telegram.com. Follow him on X: @henrytelegram