The United Illuminating Company Rate Selection Guide
The United Illuminating Company (UI), an Avangrid utility, provides electric distribution service to about 346,000 customers in southern Connecticut under the state's deregulated retail-choice market, regulated by PURA. UI offers a customer portal, Energy Analyzer with CSV/XML export, manual interval-data requests, and full supplier EDI (810/814/867), but has not implemented Green Button.
The United Illuminating Company Rate Schedule Comparison
| Schedule | Type | Rate | Best For |
|---|---|---|---|
| Rate GS - General Service | Commercial | Customer charge + delivery; Standard Service generation 13.3666 c/kWh (Jan-Jun 2026) | Small to mid-size commercial customers on standard, non-TOU service |
| Rate GST - General Service TOU | Commercial | TOU delivery; generation 13.7607 c on-peak / 10.7607 c off-peak (Jul-Dec 2025) | Commercial customers under 500 kW who can shift load off the noon-8pm peak |
| Rate LPT - Large Power TOU | Industrial | TOU large-power delivery; generation 15.3648 c on-peak / 12.36 c off-peak (Jan-Jun 2026) | Large power and industrial loads; transmission-voltage (LPT-TRA) for the largest |
| Rate GS-EVSE / GST-EVSE | EV | Dedicated EV charging station delivery rates | Commercial and public EV charging station operators |
Market Overview
UI is a regulated distribution company in Connecticut's deregulated market. Customers choose a competitive generation supplier or default to UI Standard Service, a competitively procured pass-through reset every six months. Licensed suppliers and aggregators enroll customers via EDI 814 transactions, overseen by PURA.
Need to pull your actual usage data to compare rates? See the The United Illuminating Company Data Access Guide →
Current Rate Schedules
Following PURA's Final Decision in Docket No. 24-10-04 (issued October 28, 2025), UI's distribution rates took effect for the rate year beginning November 1, 2025. PURA approved a $450,789,348 revenue requirement (8% below UI's request) with a 9.25% allowed ROE. Commercial/industrial delivery schedules below are effective November 1, 2025. Generation supply is separate: UI Standard Service generation is reset every six months and is a no-markup pass-through.
Effective: November 1, 2025 · Full Tariff Book →
| Schedule | Type | Applicability | Structure | Rate |
|---|---|---|---|---|
| Rate GS - General Service | commercial | General commercial customers (small to mid-size) on standard, non-TOU service. | Distribution service with customer/service charge plus volumetric delivery charges (see Appendix A service charges, effective Nov 1, 2025). Standard Service generation for Jan-Jun 2026 is 13.3666 cents/kWh (no markup). PURA tariff CPUCA No. 2434, effective Nov 1, 2025. | — |
| Rate GST - General Service Time-of-Use | commercial | Commercial customers electing time-of-use pricing; under 500 kW for Standard Service. | Time-of-use delivery with on-peak (Mon-Fri noon-8pm) and off-peak periods. GST Standard Service generation (Jul-Dec 2025): 13.7607 cents on-peak / 10.7607 cents off-peak. PURA tariff CPUCA No. 2435, effective Nov 1, 2025. | — |
| Rate GST-TRA - General Service TOU, Transmission Voltage | commercial | Larger commercial customers taking service at transmission voltage. | Time-of-use general service at transmission voltage with corresponding delivery charges. PURA tariff CPUCA No. 2413, effective Sep 1, 2025. | — |
| Rate LPT - Large Power Time-of-Use | industrial | Large power / industrial customers on time-of-use service. | Time-of-use large power delivery with on-peak (Mon-Fri noon-8pm) and off-peak periods. LPT Standard Service generation (Jan-Jun 2026): 15.3648 cents on-peak / 12.36 cents off-peak; customers over 500 kW take Last Resort Service. PURA tariff CPUCA No. 2437, effective Nov 1, 2025. | — |
| Rate LPT-TRA - Large Power TOU, Transmission Voltage | industrial | Large power / industrial customers served at transmission voltage. | Time-of-use large power delivery at transmission voltage, with lower delivery charges reflecting reduced distribution use. PURA tariff CPUCA No. 2417, effective Sep 1, 2025. | — |
| Rate GS-EVSE / GST-EVSE - EV Charging Station | ev | Commercial electric vehicle charging stations (standard and time-of-use). | Dedicated EV charging station rates designed to support public/commercial charging deployment. PURA tariffs CPUCA No. 2444/2445, effective Nov 1, 2025. | — |
Rate Recommendations by Use Case
Small to mid-size commercial customer
Stay on Rate GS for delivery and shop generation supply competitively.
GS is the standard commercial delivery schedule; the biggest lever is the generation component, where competitive suppliers can beat UI Standard Service (13.3666 c/kWh for Jan-Jun 2026).
- Benchmark supplier offers against Standard Service on EnergizeCT
- Avoid variable-rate plans that spike after a teaser
- Use Energy Analyzer to understand monthly usage
- Confirm the supplier is PURA-licensed
Commercial customer with shiftable load
Adopt Rate GST and shift consumption off the weekday noon-8pm peak.
GST rewards off-peak usage on both delivery and generation; off-peak generation (~10.76 c) is materially below on-peak (~13.76 c).
- Request interval data to quantify peak vs off-peak load
- Schedule heavy equipment outside noon-8pm weekdays
- Compare GST vs GS using actual interval data
- Stay under 500 kW to remain on Standard Service if desired
Large power / industrial facility
Use Rate LPT (or LPT-TRA at transmission voltage) and manage on-peak demand.
LPT is the large-power TOU schedule; transmission-voltage LPT-TRA lowers delivery charges, and on-peak generation (15.36 c) far exceeds off-peak (12.36 c), so peak management matters.
- Evaluate transmission-voltage service (LPT-TRA) eligibility
- Shift production off the noon-8pm on-peak window
- Note customers over 500 kW take Last Resort Service for supply
- Use interval data to target peak reduction
Energy consultant / aggregator serving many UI accounts
Establish EDI and SMS access; use Historical Usage Requests for bulk data.
With no Green Button or public API, EDI plus SMS and the Historical Usage Request process are the scalable paths to UI customer data.
- Become PURA-licensed and execute a UI service agreement
- Implement EDI 814/810/867 and complete testing
- Use SMS for lists, load profiles, and settlement
- Consider Nectar for multi-utility bill aggregation (docs.nectarclimate.com)
Historical Rate Trends
UI's distribution rates were last reset in PURA Docket No. 24-10-04, with a Final Decision issued October 28, 2025 for the rate year November 1, 2025 through October 31, 2026. Generation supply rates change separately every six months under the Standard Service procurement.
November 1, 2025
PURA Docket 24-10-04 Final Decision: approved a $450,789,348 distribution revenue requirement (8% below UI's $490M request) with a 9.25% allowed ROE; about $9.99/month distribution impact for an average 750 kWh residential customer. Effective Nov 1, 2025.
n/aJanuary 1, 2026
Standard Service generation reset (Jan-Jun 2026): Rate GS generation rose to 13.3666 c/kWh (~14% higher), small commercial up ~14%, reflecting winter natural gas costs.
+14%Overall trend: Rising. Distribution rates increased in the 2025 rate case, and Standard Service generation rose ~14-17% entering January 2026.
Next expected change: Standard Service generation resets July 1, 2026; next distribution rate year begins November 1, 2026.
Cost Optimization Strategies
Because UI separates delivery from supply, C&I customers have two levers: shop competitively (or time) the generation supply, and shift load to cut time-of-use delivery and on-peak generation charges. Transmission-voltage service helps the largest loads.
Competitive supply shopping
For: GS, GST, LPT
Compare licensed supplier offers on EnergizeCT against UI Standard Service generation (13.3666 c/kWh GS for Jan-Jun 2026) and lock favorable fixed rates.
Time-of-use load shifting
For: GST, LPT
On GST and LPT, move load out of the weekday noon-8pm on-peak window to capture lower off-peak delivery and generation rates.
Transmission-voltage service
For: GST-TRA, LPT-TRA
Large customers taking service at transmission voltage (GST-TRA, LPT-TRA) reduce distribution delivery charges.
Interval-data-driven analysis
For: GST, LPT, GST-TRA, LPT-TRA
Request 15-minute interval data to identify peaks, validate TOU savings, and target demand reduction before committing to a rate or supplier.
To implement these strategies, you need your 15-minute interval data. Learn how to download The United Illuminating Company interval data →
Deregulated Market Shopping
Connecticut electric customers can buy generation supply from a licensed competitive supplier or stay on UI Standard Service. UI always delivers the power and bills both components. Standard Service generation rates are reset each January 1 and July 1; for January-June 2026, Rate GS Standard Service generation is 13.3666 cents/kWh and Rate LPT is 15.3648 cents on-peak / 12.36 cents off-peak. Standard Service applies to LPT/GST customers under 500 kW; larger customers take Last Resort Service.
How to Compare The United Illuminating Company Suppliers
- 01Find your current supplier on the front of your UI bill
- 02Compare licensed supplier offers on EnergizeCT (the state rate board)
- 03Note UI Standard Service generation rates as a benchmark (reset Jan 1 and Jul 1)
- 04Switch suppliers anytime; UI continues to deliver and bill
Contract Terms for The United Illuminating Company Supply Agreements
- Standard Service generation is reset every six months (Jan 1 / Jul 1)
- Competitive supplier contracts may be fixed or variable with their own terms
- Customers over 500 kW on LPT/GST take Last Resort Service rather than Standard Service
- Delivery (distribution) charges are unaffected by supplier choice
Common Pitfalls When Shopping The United Illuminating Company Rates
- Variable-rate supplier plans can spike after a teaser period
- Check contract length, cancellation fees, and renewal/rollover terms
- Standard Service winter (Jan-Jun) rates are typically higher than summer
- Confirm the supplier is PURA-licensed before enrolling
Frequently Asked Questions
How does a C&I customer get 15-minute interval data from UI?▾
UI has AMI meters capable of 15-minute reads, but interval data is not self-service. Submit a signed Interval Data Request Service Agreement to supplier.relations@uinet.com specifying account, meter, date range, and format. Data is delivered as CSV/Excel in roughly 7-10 business days, provided 'as is' and not guaranteed to match billing reads.
Does UI support EDI for suppliers and aggregators?▾
Yes. UI fully supports ANSI X12 / NAESB Connecticut EBT transactions including 814 (enrollment/change/drop/move), 810 (invoice), 867 (historical/interval usage), and 997 (acknowledgment). Setup runs through supplier.relations@uinet.com with a service agreement and testing phase (typically 4-6 weeks), via VAN, SFTP, or web portal.
Does UI offer Green Button or a public API?▾
No. UI has not implemented Green Button Download or Connect My Data, and offers no public REST/GraphQL API. Programmatic access is through EDI and the Supplier Management System for suppliers/aggregators, plus manual Customer Data and Historical Usage Requests. Nectar can also provide customer-authorized API access to UI data — see docs.nectarclimate.com.
Can a C&I customer shop for a competitive electricity supplier?▾
Yes. Connecticut is deregulated, so UI customers can buy generation from a licensed competitive supplier or take UI Standard Service (a no-markup pass-through reset every January 1 and July 1). UI always provides delivery. Compare supplier offers at EnergizeCT (Connecticut's official rate board).
Which rate schedules apply to commercial and industrial customers?▾
Commercial/industrial delivery service is billed under PURA-approved schedules effective November 1, 2025: Rate GS (General Service), Rate GST (General Service Time-of-Use), GST-TRA (transmission voltage), Rate LPT (Large Power Time-of-Use), LPT-TRA (transmission voltage), plus EV charging rates GS-EVSE and GST-EVSE. Standard Service generation rates are set separately every six months.
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