Adding a second transmission line to serve tens of thousands of customers currently relying on a single line offers additional protection from outages due to storms or other issues.

• More than 12,000 customers in communities north of Portland like Falmouth and Cumberland currently depend on a single transmission line to bring electricity to their homes, schools, businesses and other facilities. Adding a second line to serve these areas would provide another way for electricity to reach these communities during situations like storms. This adds a second layer of protection from service interruptions for customers.

Some of CMP’s lines and power infrastructure already face electricity demand above the specific levels these grid components were designed for. These are conditions teams at CMP are seeing today, not a forecast or projection of future power demand. Increasing the amount of power this infrastructure can handle and bringing lines that can carry more electricity into places where limits are being reached can help meet existing needs. These same improvements also provide a foundation for future housing construction, business development and community-specific economic development and electrification goals.  

• This project would increase the amount of power available to 10 communities by more than 60%.
• In Portland, Westbrook and South Portland, additional capacity would support community goals for economic development and sustainability – more businesses and housing, heat pumps and electric vehicles can all increase demand on the grid.
• On the Portland Peninsula, additional capacity would support housing and mixed-use development in areas where that availability does not exist today, including parts of downtown Portland and the East End.
• A proposed transmission line from Cumberland to the Portland Peninsula and a new Portland substation could provide a foundation for future shore power. Further expansion could one day allow cruise ships to reduce emissions while docked.

Replacing substations that are more than 70 years old would provide facilities with new and reliable equipment designed to modern day standards that are safer and more efficient for crews to maintain.
 

• We’ve proposed rebuilding a substation in East Deering, which is among CMP’s substations most in need of improvement.
• We’ve proposed replacing a substation on West Elm Street in Yarmouth by expanding another substation in Cumberland. On October 9, 2026, a failure of 1980s-era equipment at the Elm Street substation affected more than 28,000 customers in 10 communities. The proposed expanded facility would prevent this type of situation.
• The Elm Street Substation is difficult for crews to maintain, with its control house basement prone to flooding and maintenance required in tight, constrained spaces that would be built differently today.