SAIDI
190 min per year
Mean outage duration per year (2023)
What This Utility Data Tells You
NSTAR Electric Company is an 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). Excluding major weather events from that total, that places this utility well below the 120–180 minute national benchmark, signaling strong grid hardening and fast restoration practices. Over the same period, SAIFI (outage events per customer) was 0.88, putting the typical customer at roughly 1 distinct interruption that year. Strip out major event days (hurricanes, ice storms) and SAIDI falls to 75.6 minutes; the difference from the headline 189.8 shows how much of the outage total came from weather rather than everyday grid issues.
NSTAR Electric Company has 4 years of continuous EIA reporting on file (2020–2023), enough to read a real trend rather than a single-year snapshot. Over that window, SAIDI moved from 235.7 down to 189.8 minutes, a trend worth noting for anyone weighing capital investment outcomes.
SAIFI
0.88 interruptions/yr
Average interruption count (2023)
Customers
463,946
Customers across Massachusetts
SAIDI vs. National Average (180 min) 47.5%
190 min/year per customer
Power-out minutes 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 including major weather events, but 75.6 minutes excluding them (the industry-standard measure of routine reliability, so the gap traces back to a major storm that year, not a chronic issue). Leaving aside major weather events, that figure comes in under the national average, pointing to above-average reliability.
What type of utility is NSTAR Electric Company?
NSTAR Electric Company is classified as a IOU serving Massachusetts.
How many customers does NSTAR Electric Company serve?
NSTAR Electric Company serves approximately 463,946 customers in Massachusetts.
How has NSTAR Electric Company's reliability changed over time?
NSTAR Electric Company has 4 years of reliability data (2020-2023). This utility's SAIDI has stayed fairly flat over the period. Review the trend table above for year-by-year detail.
Utility Profile
- Type
- IOU
- State
- Massachusetts
- Customers
- 463,946
- Annual Revenue
- $1.03B
- EIA ID
- 54913
Explore
Source: U.S. Energy Information Administration Form 861 annual electric power industry survey · ZIP service territory: OpenEI. Disclaimer: informational only, not professional advice. See full disclaimer.
Every figure on PlainUtility is rendered directly from the U.S. Energy Information Administration's Form 861 reliability data, no number is typed in by an editor. This utility's SAIDI/SAIFI figures are rendered directly from EIA Form 861 reliability files. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2020-2023.