SAIDI
190 min per year
Average outage minutes (2023)
What This Utility Data Tells You
NSTAR Electric Company is a investor-owned utility operating in Massachusetts under EIA identifier 54913. It reports service to approximately 463,946 customer accounts and generated about $1.03 billion in annual electric revenue, with a service footprint spanning 289 ZIP codes. As an investor-owned utility, it operates under state public utility commission oversight that reviews rate cases and reliability performance.
In 2023, the average NSTAR Electric Company customer experienced 189.8 minutes of power interruptions — a metric called SAIDI (System Average Interruption Duration Index). That sits within the 120–180 minute national benchmark range, indicating performance typical of U.S. distribution utilities. SAIFI — the average number of outage events per customer — was 0.88 for the same period, so customers statistically faced roughly 1 distinct interruption that year. Excluding major event days (hurricanes, ice storms), SAIDI drops to 75.6 minutes — the gap between that figure and the headline 189.8 reveals how much weather, not day-to-day infrastructure, drove outages.
The EIA dataset includes 4 years of continuous reporting (2020–2023) for NSTAR Electric Company, which lets you see whether reliability is trending up or down rather than judging from a single snapshot. SAIDI has improved from 235.7 to 189.8 minutes over that window — a meaningful direction for prospective customers and regulators watching capital investment outcomes. All figures on this page come directly from EIA Form 861, the federal annual electric power industry survey, with service territory ZIPs sourced from OpenEI — you can cross-reference them with your own utility bill or use them when comparing providers before relocating.
SAIFI
0.88 interruptions/yr
Outage frequency (2023)
Customers
463,946
Served in Massachusetts
SAIDI vs. National Average (180 min) 47.5%
190 minutes per customer per year
Minutes without power per year (2023)
Reliability Trend (2020–2023)
| Year | SAIDI (min) | SAIDI nMED | SAIFI | Customers |
|---|---|---|---|---|
| 2020 | 235.7 | 65.0 | 1.140 | 1,446,211 |
| 2021 | 640.8 | 75.8 | 1.098 | 1,450,541 |
| 2022 | 196.7 | 68.5 | 1.033 | 1,471,114 |
| 2023 | 189.8 | 75.6 | 0.884 | 1,307,124 |
SAIDI nMED = SAIDI without major event days. Source: EIA Form 861.
Service Area
NSTAR Electric Company serves 289 ZIP codes in Massachusetts.
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Frequently Asked Questions
How reliable is NSTAR Electric Company?
NSTAR Electric Company had a SAIDI of 189.8 minutes in 2023, meaning the average customer experienced about 190 minutes of outages that year. This is near the national average.
What type of utility is NSTAR Electric Company?
NSTAR Electric Company is classified as a IOU serving Massachusetts. Investor-owned utilities (IOUs) are for-profit companies regulated by state public utility commissions.
What does SAIDI mean for NSTAR Electric Company?
SAIDI (System Average Interruption Duration Index) measures the average total minutes per year that a customer of NSTAR Electric Company experiences power outages. A lower SAIDI indicates better reliability. The national average is roughly 120-180 minutes per year, so comparing NSTAR Electric Company's SAIDI to that benchmark shows whether this utility is above or below average.
How many customers does NSTAR Electric Company serve?
NSTAR Electric Company serves approximately 463,946 customers in Massachusetts. Customer count can affect reliability metrics because larger utilities may face different infrastructure challenges compared to smaller ones.
How has NSTAR Electric Company's reliability changed over time?
NSTAR Electric Company has 4 years of reliability data (2020-2023). SAIDI has remained relatively stable over this period. Review the trend table above for year-by-year detail.
What is SAIDI without major event days?
SAIDI "without major event days" (SAIDI nMED) excludes outages caused by hurricanes, ice storms, and other catastrophic weather events. It better reflects day-to-day infrastructure reliability rather than vulnerability to extreme weather. Both standard SAIDI and SAIDI nMED are shown in the reliability trend table above.
Utility Profile
- Type
- IOU
- State
- Massachusetts
- Customers
- 463,946
- Annual Revenue
- $1.03B
- EIA ID
- 54913
Related Data
Guides
Data Source: U.S. Energy Information Administration Form 861 annual electric power industry survey. ZIP service territory from OpenEI.
Related
Data sourced from official EIA reliability statistics and OpenEI utility rate database. See our methodology for details. Retrieved and formatted by PlainUtility Editorial
Disclaimer: This information is provided for informational purposes only and does not constitute professional advice. Data is sourced from the U.S. Energy Information Administration (EIA) Form 861. Consult a qualified professional before making decisions based on this data.
Read our methodology — how this data is sourced, computed, and verified.