Utility Tariff Analysis · Updated September 2026

Connecticut's New England Transmission Cost Exposure: What It Means for AI Data Centre Siting in Connecticut

No dedicated large-load rate class yet in Connecticut has not yet produced a state-specific large-load tariff. Connecticut ratepayers are instead exposed to data centre-driven cost pressure indirectly, through the same regional New England Transmission Owners FERC return-on-equity dispute affecting Massachusetts, Rhode Island, Maine and New Hampshire — where a March 2026 FERC order set a lower base ROE and required refunds, while transmission owners have separately proposed an 11.39 percent forward-looking ROE partly justified by data centre-driven grid investment.

Connecticut's New England Transmission Cost Exposure — AI data centre infrastructure

Connecticut's New England Transmission Cost Exposure

CT

Eversource / United Illuminating

FERC ROE proceedings (New England Transmission Owners)

Regulatory docket / filing reference

No dedicated large-load rate class yet in Connecticut

Who the tariff applies to

No dedicated large-load rate class yet in Connecticut has not yet produced a state-specific large-load tariff. Connecticut ratepayers are instead exposed to data centre-driven cost pressure indirectly, through the same regional New England Transmission Owners FERC return-on-equity dispute affecting Massachusetts, Rhode Island, Maine and New Hampshire — where a March 2026 FERC order set a lower base ROE and required refunds, while transmission owners have separately proposed an 11.39 percent forward-looking ROE partly justified by data centre-driven grid investment.

Also active in Connecticut: Without a dedicated tariff, a large load locating in Connecticut currently negotiates under standard commercial and industrial rate schedules — worth confirming directly with Eversource or United Illuminating before assuming Virginia- or Ohio-style minimum-take terms apply.

Figures compiled from the Edison Electric Institute's "Large Load Projects and Tariffs" (September 2026) member-company summary and public regulatory filings. Confirm current tariff terms directly with Eversource / United Illuminating and the relevant state public utility commission before relying on any figure for a capital decision.

Weighing Connecticut against another state or a Canadian province with a different rate and interconnection picture entirely? Run both sides of the comparison through our licensed AI data centre cost configurator — it applies each jurisdiction's actual power rate, tax treatment and large-load tariff rules to the same seven build configurations.

Model This State on Your Own Site

Every figure above comes from the same power-cost and tariff dataset behind the SCR AI Build Configurator — a licensed, embeddable widget that models seven data centre build configurations against all nine Canadian provinces and all 50 US states plus DC, returning capital expenditure by line item, energy cost, revenue by commercial structure, EBITDA and payback.

LicencePrice (CAD)Who it suits
Standard$4,000 / domain / yearAdvisors who need three lease-model configurations and a clipboard summary
Pro$10,000 / domain / yearConsultants who send CSV deliverables to clients and want all seven configurations
EnterpriseFrom $25,000 / year, up to 3 domainsDevelopers and EPC firms who want the model on their own cost basis with attribution removed

Not ready for an annual licence? A one-time Site Screening Report ($950, one site) runs the same model for a single build without embedding anything.

Frequently Asked Questions

What is Connecticut's New England Transmission Cost Exposure?

No dedicated large-load rate class yet in Connecticut has not yet produced a state-specific large-load tariff. Connecticut ratepayers are instead exposed to data centre-driven cost pressure indirectly, through the same regional New England Transmission Owners FERC return-on-equity dispute affecting Massachusetts, Rhode Island, Maine and New Hampshire — where a March 2026 FERC order set a lower base ROE and required refunds, while transmission owners have separately proposed an 11.39 percent forward-looking ROE partly justified by data centre-driven grid investment.

Why did Eversource / United Illuminating introduce this large-load structure?

To ensure the cost of new generation, transmission and distribution infrastructure built to serve very large customers, chiefly hyperscale data centres, is paid for by those customers rather than spread across the general rate base of residential and small commercial ratepayers.

What large data centre projects are already active in Connecticut?

Without a dedicated tariff, a large load locating in Connecticut currently negotiates under standard commercial and industrial rate schedules — worth confirming directly with Eversource or United Illuminating before assuming Virginia- or Ohio-style minimum-take terms apply.

Does this tariff replace Connecticut's standard commercial and industrial rates?

No. Connecticut's New England Transmission Cost Exposure sits above Eversource / United Illuminating's standard commercial and industrial rate schedules and applies specifically to customers that meet or exceed the large-load threshold described above. Smaller commercial and industrial loads continue to be billed under existing rate schedules.

How can I model a Connecticut data centre build against this tariff and other states?

The SCR AI Build Configurator applies Connecticut's power cost, tax treatment and large-load tariff rules alongside all other US states and Canadian provinces, so a Connecticut scenario can be compared line-by-line against any alternative site.