Utility-Owned vs. Customer-Owned Substations for Data Centers

Every large data center needs a substation that steps transmission voltage down to the medium voltage that feeds the campus. The ownership question is about where the utility’s system ends and the customer’s begins. That point, the point of delivery, sets the voltage at which power is metered, which tariff applies, and who owns, operates and repairs each piece of equipment.

In the utility-owned model, the utility builds and owns the high-voltage yard, the main power transformers and usually the medium-voltage breakers, and delivers power to the customer at distribution voltage. In the customer-owned model, the utility brings a transmission line to a switching point and the customer owns everything downstream. Black & Veatch describes the second model as building substations that the client will own, allowing the local utility to connect directly with its transmission lines.³

A third, hybrid model is common: the customer designs and builds the station to utility standards, then transfers it to the utility, which owns and maintains it afterward. The configuration of the yard (ring bus, breaker-and-a-half) is a separate decision from who owns it, although the utility will usually dictate the configuration of anything it is going to own.

With a utility-owned substation, the customer historically paid for the station over time through rates, sometimes with a contribution in aid of construction for facilities built only for that customer. With a customer-owned substation, the customer pays the full capital cost up front and then pays a lower monthly rate, because the utility is not carrying the transformation equipment or its losses.

Utility tariffs show the size of that monthly credit. Entergy Arkansas’s voltage adjustment rider reduces the monthly demand charge by $2.18 per kW, and reduces demand and energy losses by 1.0%, where service is delivered at primary voltage and the customer owns and maintains all transformation facilities.¹ Green Mountain Power’s 2026 commercial and industrial schedule lists a 21.65% subtransmission voltage discount, a 23.04% discount for loads above 20 MW and a separate transformer ownership credit.² Discounts vary widely by utility and change with each rate case, so confirm the current tariff sheet.

The other side of the ledger is shifting. Virginia regulators ordered Dominion Energy to directly assign certain transmission costs, such as a new substation or dedicated line, to the data center customers that trigger them,⁶ and in August 2026 the State Corporation Commission proposed a process for working out those mechanisms in a separate docket.¹² Pennsylvania’s May 2026 model tariff for loads above 50 MW (or 100 MW in aggregate) calls for upgrades to be paid up front through contribution in aid of construction, though the order is guidance utilities may or may not adopt.⁷ Where those rules apply, a data center pays for its dedicated station either way, and the real question becomes who owns and runs it afterward. Our guides to large-load tariffs and transmission cost allocation cover those rules.

The strongest argument for customer ownership is time. Black & Veatch reports that utilities often say it will be five years or more before they can provide the circuits and substations for a proposed campus, and that customer ownership lets the owner better control schedule and cost.³ In its own account, a sponsored industry article, the firm says building and running your own station can accelerate development when the interconnecting utility has resource or capital constraints, if regional regulations and the utility allow it.¹³ Those are a contractor’s claims, not independent data, but they match the logic: an owner can hire its own engineer, order equipment before the utility’s budget cycle, and run substation work in parallel with the building.

Early procurement is where most of the time is won or lost. On a 300 MW hyperscale project, Black & Veatch used progressive design-build to buy long-lead items early and reported that quoted lead times for circuit breakers averaged about 85 weeks.¹⁴ Wood Mackenzie projected 2025 supply deficits of about 30% for power transformers and 10% for distribution transformers, with roughly 80% of U.S. power transformers expected to be imported.⁸ Ownership does not create equipment that does not exist; it only decides whose purchase order is in the queue. See transformer and switchgear lead times for current procurement patterns.

Control also covers design. An owner can choose its own protection philosophy, metering, spare transformer strategy and expansion bays, and can match the station to the campus ramp schedule. A utility will build to its system standards, which are proven but may not anticipate a second phase.

Practice varies by utility, and the utility’s answer usually decides the question before the customer’s preference does. Rocky Mountain Power told Utah regulators that hyperscale data centers take service at 46 kV or higher through a customer-owned substation, which it described as the most cost-effective way to serve large contracted loads, and noted load requests above 100 MW.⁴ Other utilities insist on owning any station connected to their transmission system.

Build-and-transfer is a middle path. A PG&E advice letter describes an agreement under which Google builds certain facilities and transfers ownership to PG&E once they are completed and approved; to protect other customers, the refund is the lower of a binding cost estimate or actual cost.⁵ In practice this lets the customer drive the schedule while the utility ends up with an asset it is willing to maintain.

Ownership is permanent work. NFPA 70B, which for decades was a recommended practice, became a standard in 2023, changing its language from what practices “should” be to what they “shall” be.⁹ It requires the equipment owner to implement and document an electrical maintenance program, with intervals set by an equipment condition assessment.¹⁵ Whether it is enforceable at a given site depends on adoption by the local authority having jurisdiction.⁹

An owner also needs spares, relay settings management, switching procedures and qualified people on call. A utility can roll a mobile transformer or pull a spare from its fleet; a single customer usually cannot, so customer-owned stations often carry a spare main transformer or a second transformer sized to carry the load. Our guide to redundant utility feeds covers how dual sources change that calculation.

Reliability regulation is the newest factor. NERC posted draft registry criteria for computational loads in April 2026 using 20 MW at 60 kV or above,¹⁰ and a revised proposal circulated in August 2026 used at least 50 MW served through equipment connected at 100 kV or above.¹⁶ In July 2026, FERC directed NERC to file reliability standards and registration criteria for large computational loads by December 31, 2026.¹¹ Final rules were not in place as of October 2026, but a customer that owns its transmission-voltage station also owns its protection and ride-through settings, which is where those standards are likely to focus. See NERC reliability and large loads.

Customer ownership tends to make sense when the load is large and long-lived, the utility allows it and offers a meaningful transmission-voltage rate, and the owner has (or will contract for) a substation operations team. Utility ownership tends to fit smaller or uncertain loads, utilities that will not accept customer-owned stations, and owners who want the utility to carry restoration risk. Build-and-transfer fits when schedule matters but the owner does not want a permanent high-voltage operation.

1. 01Does the utility permit customer-owned substations at this voltage, and under which tariff or rider?
2. 02What is the transmission-voltage rate or credit, and how has it changed in recent rate cases?
3. 03Will dedicated facilities be directly assigned or billed as contribution in aid of construction regardless of ownership?
4. 04Is a build-and-transfer option available, and what are the refund and cost-cap terms?
5. 05Who orders the transformers and breakers, and when?
6. 06What maintenance, spares and compliance obligations follow ownership?

Raise these at the first meeting in the large-load interconnection process, before the parcel is under contract, since the answer changes how much land the yard needs and how the budget is built. BlackForge screens sites for power path and substation options; you can get a site reviewed.