United Illuminating Co
Investor Owned electric utility · Connecticut · #130 of 3,199 U.S. utilities by customers · EIA utility #19497
United Illuminating Co is a investor owned electric utility serving 277,914 customers in Connecticut. In 2025 it sold 2,026 gigawatt-hours of electricity for $707.19M in revenue, an average realized rate of 34.91¢ per kWh across all customer classes and 35.40¢ per kWh for residential customers. Its reported service territory covers 2 counties. EIA records its activities as: transmission, buying transmission, distribution.
Customers, sales and rates by customer class (2025)
| Class | Customers | Sales (GWh) | Revenue | Avg realized rate | Share of sales |
|---|---|---|---|---|---|
| Residential | 261,151 | 1,618 | $572.78M | 35.40¢ | |
| Commercial | 16,545 | 381 | $128.95M | 33.84¢ | |
| Industrial | 217 | 13.1 | $3.58M | 27.37¢ | |
| Transportation | 1 | 13.6 | $1.88M | 13.80¢ | |
| Total | 277,914 | 2,026 | $707.19M | 34.91¢ |
Average realized rate = revenue divided by sales as reported on EIA Form 861. It blends fixed charges, demand charges and riders into one per-kWh figure; it is not the utility's tariff rate. Estimated residential bill assumes the average residential customer's actual 2025 usage (516 kWh/month).
Five-year trend
| Year | Customers | Sales (GWh) | Revenue | Residential rate |
|---|---|---|---|---|
| 2021 | 260,585 | 2,122 | $497.83M | 25.19¢ |
| 2022 | 288,552 | 2,374 | $541.27M | 23.55¢ |
| 2023 | 281,971 | 2,135 | $668.76M | 33.16¢ |
| 2024 | 273,388 | 2,295 | $715.25M | 34.04¢ |
| 2025 | 277,914 | 2,026 | $707.19M | 35.40¢ |
Reliability (2025)
Average outage time (SAIDI): 73 minutes per customer per year
Average outages (SAIFI): 0.66 per customer
Average restoration time (CAIDI): 111 minutes
As reported for Connecticut under the IEEE standard, with major event days included where the standard reports them. Lower is better; see the reliability rankings.
Energy supply (2025)
Net generation: 0.0 GWh
Wholesale power purchased: 2,163 GWh
Winter peak demand: 768 MW
Energy losses: 6.3% of energy handled
Meters & rooftop solar (2025)
Smart (AMI) meters: 91.7% of 352,949 meters
Customer-sited generation (net metering): 28,196 installations, 265.9 MW of capacity
This utility also reported 70,349 delivery-only customers (2,850 GWh delivered) in 2025. Delivery figures are excluded from the totals above because the same electricity is also reported by the energy supplier - see Methodology.
Counties served
Fairfield, CTNew Haven, CT
Other large utilities in Connecticut
- Connecticut Light & Power Co - 1,072,114 customers, residential 28.88¢
- Think Energy, LLC - 90,425 customers, residential 11.78¢
- Town Square Energy - 85,979 customers, residential 13.09¢
- Town of Wallingford - (CT) - 25,123 customers, residential 17.78¢
- City of Norwich - (CT) - 20,996 customers, residential 23.35¢
- Groton Dept of Utilities - (CT) - 14,193 customers, residential 18.05¢
- XOOM Energy Connecticut, LLC - 10,627 customers, residential 13.09¢
- City of South Norwalk - (CT) - 7,439 customers, residential —
All Connecticut utilities and rates
Source: U.S. Energy Information Administration, Form EIA-861 2025 (filed by the utility; figures as published). Utility #19497 in the EIA frame.