Massachusetts Electrical Utility Companies and Service Territories
Massachusetts electricity delivery operates through a regulated utility framework in which specific companies hold exclusive franchise rights to distribute power within defined geographic service territories. This page maps the major investor-owned and municipal utilities serving Massachusetts, explains how service territory boundaries function, identifies the regulatory structure governing these entities, and outlines the practical implications for property owners, contractors, and developers navigating interconnection, metering, and outage response across the state.
Definition and scope
A utility service territory is a geographically defined area within which a single distribution company holds a franchise to deliver electricity to end-use customers. In Massachusetts, the Department of Public Utilities (DPU) — operating under Massachusetts General Laws Chapter 164 — grants these franchise rights and regulates rates, reliability standards, and interconnection procedures for investor-owned utilities. Municipal light plants (MLPs) operate under separate statutory authority and are governed by Chapter 164, Sections 34–77, with oversight from their respective municipal boards rather than the DPU.
Massachusetts electrical service territory coverage does not apply to federal enclaves, tribal lands, or out-of-state portions of regional transmission systems operated by ISO New England. Transmission infrastructure above 69 kilovolts falls under Federal Energy Regulatory Commission (FERC) jurisdiction, not the DPU. This page addresses distribution-level utilities serving Massachusetts customers; it does not address retail electricity suppliers, competitive supply contracts, or wholesale market participants regulated exclusively by FERC. For the broader regulatory framework governing electrical systems statewide, see Regulatory Context for Massachusetts Electrical Systems.
How it works
Electricity in Massachusetts reaches customers through a two-layer structure: the bulk transmission grid managed by ISO New England and the local distribution networks owned and operated by individual utilities. Distribution companies purchase power on wholesale markets (or through long-term contracts) and deliver it over their low- and medium-voltage networks — typically ranging from 4 kilovolts to 35 kilovolts — to metered service points at individual premises.
Investor-owned utilities (IOUs) serve the majority of Massachusetts customers and file rates, reliability plans, and capital investment proposals with the DPU for approval. Municipal light plants (MLPs) are publicly owned utilities operated by 41 communities across the state, according to the Massachusetts Municipal Wholesale Electric Company (MMWEC), and set their own rates through municipal governance processes rather than DPU rate cases.
The two largest IOUs are:
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Eversource Energy (formerly NSTAR / Western Massachusetts Electric) — serves approximately 1.4 million electric customers across eastern Massachusetts, including the greater Boston metropolitan area, the South Shore, and Cape Cod, as well as portions of western Massachusetts formerly served by Western Massachusetts Electric. Eversource is regulated by the DPU and files service quality metrics annually. For detailed territory and service comparison, see Eversource and National Grid in Massachusetts.
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National Grid (Niagara Mohawk Holdings / KeySpan legacy) — serves approximately 1.1 million electric customers primarily in central and southeastern Massachusetts, including Worcester, New Bedford, and Fall River.
Unitil Corporation serves a smaller territory in the Fitchburg and Leominster area of north-central Massachusetts, along with portions of southern New Hampshire.
Common scenarios
New service connections: When a property is developed or a service entrance is upgraded, the property owner or licensed electrical contractor submits a service application to the territory's distribution company. The utility establishes metering, sets the service type (overhead or underground), and specifies the allowable service entrance conductor size. Massachusetts 527 CMR 12 (the Massachusetts Electrical Code, based on NFPA 70 / National Electrical Code 2023 edition) governs the customer-side wiring; utility tariff schedules govern the meter and service lateral. Details on the service entrance side are covered at Electrical Service Entrance Massachusetts.
Interconnection for distributed generation: Solar photovoltaic systems, battery storage, and small generators require interconnection applications under each utility's DPU-approved tariff. Eversource and National Grid each publish interconnection procedures aligned with the DPU's Net Metering regulations under 220 CMR 18. Projects up to 60 kilowatts (AC) in Massachusetts qualify for net metering under the small generator threshold; systems above 1 megawatt follow a more complex interconnection study process. See Solar Electrical Systems Massachusetts for installation-level detail.
Outage response and reliability complaints: The DPU enforces service quality standards through annual reporting requirements. Utilities must meet defined metrics for System Average Interruption Duration Index (SAIDI) and System Average Interruption Frequency Index (SAIFI). Customers experiencing persistent outages in a territory may file complaints directly with the DPU through its consumer complaint process.
MLP territory adjacency: Boundary parcels — particularly in communities such as Concord, Littleton, or Braintree — may adjoin both MLP and IOU service zones. The applicable utility is determined by the street address's assigned service territory, not by proximity to infrastructure. Contractors working across town lines should verify territory assignment before submitting permit paperwork, as inspection and metering contacts differ by utility.
Decision boundaries
The distinction between MLP and IOU territory carries concrete operational consequences:
| Factor | Investor-Owned Utility (IOU) | Municipal Light Plant (MLP) |
|---|---|---|
| Rate-setting authority | DPU (regulatory approval required) | Municipal light board |
| Interconnection tariff | DPU-approved; standardized statewide | Each MLP sets own tariff |
| Complaint escalation | DPU consumer division | Municipal board; DPU limited role |
| Net metering eligibility | Statewide program under 220 CMR 18 | Varies by MLP; some opt in |
| Emergency contact | Utility 24-hour dispatch | MLP operations center |
For property transactions, utility territory identity affects what energy efficiency programs are available. Eversource and National Grid each administer Mass Save programs under DPU-approved energy efficiency plans, while MLPs operate separate programs (or participate through MMWEC). The Massachusetts Electrical Energy Efficiency Programs page maps these program distinctions.
Permitting does not change by utility territory — electrical permits in Massachusetts are issued by the local building or electrical inspection department under 527 CMR 12, and inspection authority rests with the local electrical inspector regardless of which distribution company serves the address. The Massachusetts Electrical Inspector Role page covers inspection jurisdiction in detail.
For a general orientation to Massachusetts electrical infrastructure and services, the Massachusetts Electrical Authority home page provides structured entry points across licensing, code, and utility topics.
References
- Massachusetts Department of Public Utilities (DPU)
- Massachusetts General Laws Chapter 164 — Manufacture and Sale of Gas and Electricity
- ISO New England — Regional Transmission Organization
- Massachusetts Municipal Wholesale Electric Company (MMWEC)
- 220 CMR 18 — Net Metering Regulations, Massachusetts DPU
- 527 CMR 12 — Massachusetts Electrical Code
- Mass Save Energy Efficiency Programs
- Federal Energy Regulatory Commission (FERC)
- Eversource Energy — Massachusetts Service Territory
- National Grid USA — Massachusetts Electric