LEARN / GLOSSARY
Large load
A single customer whose electricity demand is big enough to require its own study and, increasingly, its own tariff. ERCOT applies the term to customers requiring 75 megawatts or more.
Definition
A large load is an individual customer whose connection materially affects system planning. Definitions are set by system operator rather than by statute, and ERCOT applies the term to customers requiring 75 megawatts or more. Data centers dominate the current category, with industrial facilities and electrolysers contributing.
Why the dictionary version is insufficient
Large load sounds like a size category. It is closer to a regulatory status, carrying its own interconnection process, its own study requirements and, in a growing number of jurisdictions, its own financial commitment obligations. Whether a facility crosses the threshold changes the process it faces, not merely the scale of it.
Measurement noteLarge load interconnection requests are not counted in the national generation queue datasets, which cover generation seeking transmission connection only. Large load queues are administered utility by utility and disclosed inconsistently, so the constraint most relevant to industrial siting is the one with the least public evidence.
Why it matters for capacity
Whether a large load can be curtailed during emergencies changes its effect on planning reserve margins substantially, which is why flexibility has become a negotiating position rather than a technicality. NERC notes that because new large loads can be curtailed during energy emergencies, their effect on ERCOT margins is smaller than their raw size implies.
Related terms
Load factor · Interconnection queue · Planning reserve margin
Appears in
Why Electricity Demand Is Growing Again
How Electricity Demand Is Measured
Read next
Why Electricity Demand Is Growing Again
Sources
- North American Electric Reliability Corporation, 2025 Long-Term Reliability Assessment. nerc.com
- Belfer Center, Data Centers and Large-Scale Electric Growth, citing ERCOT large load reporting. belfercenter.org
- U.S. Energy Information Administration, Hourly Electric Grid Monitor, form EIA-930. eia.gov