CMP nears completion on ‘3-phase’ power upgrade to town facilities in Harpswell

Central Maine Power is nearly finished with a project to upgrade more than three miles of power infrastructure leading to the Harpswell Town Office and surrounding facilities, according to the utility. The town needs the upgrade to make planned improvements such as a new office heating, ventilation and air conditioning (HVAC) system and recycling center enhancements.

Crews have been working along Mountain Road to upgrade power poles and add more lines to enable what’s known as “three-phase power” to facilities including the town office and adjacent A. Dennis Moore Recycling Center & Transfer Station.

The project will upgrade town facilities from basic, “single-phase” power to three-phase power, said CMP spokesperson Dustin Wlodkowski. Work was roughly 95% completed as of late May, he said.

“If you looked at power moving through our lines with special instruments like an oscilloscope, it would appear visually as a wave,” Wlodkowski said. “In a single-phase system, there is only one wave. In a three-phase system, there are three waves in a pattern. The three-phase system has three times the capacity of one that is single-phase.”

Typically, lower-usage power customers such as residents only need single-phase service, while industrial customers and other users with more substantial energy requirements may require three-phase, he said.

“In a single-phase system, there are typically two wires,” Wlodkowski said. “At CMP, our three-phase systems generally have four wires – three that carry power and one that is a neutral ground.”

The utility has been installing taller poles with special crossbars at the top to carry the additional wires. Three-phase systems produce a more stable power supply that is required for certain large motors and other energy-intensive uses.

Rick Nendze, a line department supervisor at CMP, said three-phase power infrastructure generally exists in areas near power substations or with lots of heavy energy users. More rural areas and those farther away from substations are usually single-phase, he said.

However, customers can request an upgrade to three-phase power if they need it, Nendze said, which is what the town of Harpswell did.

“It’s very situational,” Wlodkowski added. “When there’s a need, then we can come in and meet the need.”

Harpswell Select Board Chair Kevin Johnson said the request originated with a desire to upgrade the town office’s HVAC system, which doesn’t always heat and cool the facility consistently. An engineer told town officials they could upgrade to a more efficient HVAC system if the building had access to three-phase power, he said.

“We were having a meeting with CMP, and I asked (CMP Community Relations Manager Greg Thompson), ‘What are the chances of three-phase coming down the Mountain Road?’ and he looks and he goes, ‘Yeah, we can do that,’” Johnson said.

Nendze said Harpswell didn’t have to pay for the upgrade, which will help CMP by allowing it to provide enhanced service to other customers along the line. It also will add redundancy to help isolate outages to a smaller area when a line goes down in a storm, he said.

Wlodkowski said entities requesting a three-phase upgrade often do have to cover the costs, and that it depends in part on whether the work coincides with other CMP projects.

One customer who is looking forward to the upgrade’s completion is Charles Perow Jr., manager of Harpswell’s recycling center and transfer station. The facility is scheduled to have its entire electrical system upgraded to allow its waste compactors to run more cheaply and efficiently, he said.

“Currently, we have to make our own three-phase power,” Perow said. “We take regular line voltage, run it through what they call a (rotary phase converter), and (it) runs the full eight hours that we’re open in order to provide three-phase power to run the compactors.”

Having three-phase power already available to the facility will save the town money on both power usage and equipment, he said.

The cost savings on power inverter equipment alone will likely be at least $60,000, Perow said, and the facility will no longer have to generate its own three-phase power all day, much of which goes unused.

“We’re basically generating power that we only use maybe one-tenth of the time,” he said.

Perow said the entire recycling center facility is scheduled for an overhaul that will include new building insulation and roofing in addition to the electrical system upgrade. That project is scheduled to begin in spring 2025 and will take an estimated four to six months to complete, he said.

Johnson, the Select Board chair, said town officials already have begun the process of finding and selecting a vendor to do the town office’s HVAC system upgrade, now that the needed utility infrastructure is in place.

“Say what you want about CMP – they’re good to Harpswell,” he said.

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