SAN ONOFRE
SubstationCalifornia · SAN DIEGO GAS & ELECTRIC
At a glance
SAN ONOFRE is an electric transmission substation in California, on SAN DIEGO GAS & ELECTRIC's transmission network. It is classified as high-voltage (230 kv) and connects 9 transmission lines. Substation proximity is one of the strongest speed-to-power signals for siting a datacenter — interconnection distance to an energized, high-voltage bus is often the binding constraint on time-to-energization.
Voltage & classification
Ownership
Connected transmission lines
Lines terminating at or passing through this substation, by HIFLD line ID, highest voltage first.
| Line ID | Voltage | Owner | Status | Length |
|---|---|---|---|---|
| #301947 | 230 kV | SAN DIEGO GAS & ELECTRIC | IN SERVICE | 28.5 mi |
| #303689 | 230 kV | SAN DIEGO GAS & ELECTRIC | IN SERVICE | 40.1 mi |
| #305652 | 230 kV | SAN DIEGO GAS & ELECTRIC | IN SERVICE | 18.2 mi |
| #306654 | 230 kV | SAN DIEGO GAS & ELECTRIC | IN SERVICE | 28.5 mi |
| #309729 | 230 kV | SAN DIEGO GAS & ELECTRIC | IN SERVICE | 17.8 mi |
| #309884 | 230 kV | SAN DIEGO GAS & ELECTRIC | IN SERVICE | 6.9 mi |
| #309888 | 230 kV | SAN DIEGO GAS & ELECTRIC | IN SERVICE | 6.9 mi |
| #310241 | 230 kV | SAN DIEGO GAS & ELECTRIC | IN SERVICE | 23.3 mi |
| #311062 | 230 kV | SAN DIEGO GAS & ELECTRIC | IN SERVICE | 17.8 mi |
Nearby datacenter candidate sites
Scored candidate sites within roughly 25 miles of SAN ONOFRE, ranked by DC Readiness. Sites this close to an energized substation carry a strong speed-to-power advantage.
| Site | Type | State | County | Voltage | Capacity | Queue wait | Score |
|---|---|---|---|---|---|---|---|
| VALLEY | Substation-Adjacent | CA | Orange County | 500 kV | 1,000 MW | 7.6 yrs | 62.3 |
| INLAND EMPIRE | Substation-Adjacent | CA | Orange County | 500 kV | 1,000 MW | 7.6 yrs | 62.3 |
| SAN ONOFRE | Substation-Adjacent | CA | Orange County | 230 kV | 300 MW | 7.6 yrs | 58.4 |
| JOHANNA | Substation-Adjacent | CA | Orange County | 230 kV | 300 MW | 7.6 yrs | 58.0 |
| ENCINA | Substation-Adjacent | CA | San Diego County | 230 kV | 300 MW | 7.6 yrs | 56.8 |
| SANTIAGO | Substation-Adjacent | CA | Orange County | 230 kV | 300 MW | 7.6 yrs | 56.8 |
| ELLIS | Substation-Adjacent | CA | Orange County | 230 kV | 300 MW | 7.6 yrs | 56.6 |
| SHADOWRIDGE | Substation-Adjacent | CA | San Diego County | 230 kV | 300 MW | 7.6 yrs | 56.4 |
How does SAN ONOFRE compare with other substations in California?
California has 4,260 substation records in HIFLD, of which 3,003 carry a station name; the rest are unnamed tap points, risers and line ends. 384 named substations in the state are in SAN ONOFRE's 230–344 kV band (13% of named stations). 44 sit in a higher band. 44 named substations in California operate at 345 kV or above. The highest voltage recorded in the state is 500 kV, and the state median is 69 kV.
Who owns the transmission lines at SAN ONOFRE?
The 9 connected lines listed above are owned by SAN DIEGO GAS & ELECTRIC. Line voltages range from 230 kV to 230 kV. Their combined recorded length is about 188 miles.
How do candidate sites near SAN ONOFRE score?
The 8 highest-scoring candidate sites within about 25 miles range from 56 to 62 on the 0–100 DC Readiness scale. They fall in Orange County, San Diego County. The California average across 8,490 scored sites is 45.4. 1,573 of those California sites are classed as substation sites (candidate locations generated at an existing substation).
Frequently asked questions
What voltage is SAN ONOFRE substation?
SAN ONOFRE has a maximum voltage of 230 kV. That places it in the 230–344 kV band. The median named US substation in this dataset is 115 kV, so SAN ONOFRE is above the national midpoint.
How many transmission lines connect to SAN ONOFRE substation?
9 transmission lines terminate at or pass through SAN ONOFRE in the HIFLD line data. The connected lines listed here run at 230 kV. Together the listed lines cover about 188 miles.
Who owns SAN ONOFRE substation?
HIFLD does not publish substation owners directly. Most of the transmission lines that end at SAN ONOFRE belong to SAN DIEGO GAS & ELECTRIC. GridCensus derives this from the line data, so confirm ownership with the utility for anything contractual.
Where is SAN ONOFRE substation located?
SAN ONOFRE is in California at 33.3694, -117.5536. The datacenter candidate sites closest to it are in Orange County, San Diego County.
Are there datacenter candidate sites near SAN ONOFRE substation?
GridCensus lists at least 8 scored candidate sites within roughly 25 miles of SAN ONOFRE. The highest-scoring is VALLEY at 62/100. Across California, the average DC Readiness score is 45.4.
Other 230 kV substations in California
- NEWARK· 30 lines
- COTTONWOOD· 21 lines
- RIO OSO· 20 lines
- BELLOTA· 19 lines
- ELLIS· 18 lines
- PITTSBURG· 18 lines
- EL CENTRO· 17 lines
- MOORPARK· 17 lines
- All named substations in California· 3,003 stations
- Datacenter candidate sites in California· 8,490 sites
- Brownfield and retired plant sites in California
- Substations by state
About this data
Source: HIFLD Electric Substations and Transmission Lines (U.S. Department of Homeland Security), as published June 29, 2026. See the methodology for how records are matched, cleaned and scored.
Cite as: GridCensus, “SAN ONOFRE substation, California”, https://gridcensus.com/substations/california/san-onofre-ae08430a (data as of June 29, 2026).
Dataset updated . Screening estimates derived from public data sources.
Substation attributes are derived from public HIFLD / EIA infrastructure data and may lag real-world upgrades or retirements. Voltage and connected-line counts are screening figures — confirm available capacity and interconnection terms directly with the operating utility and ISO.
Go deeper than the public screen
Every site and score for SAN ONOFRE substation, California is free to browse. Pro adds Watchtower on 25 sites, alerts when new candidate sites, datacenters or interconnection-queue requests appear in your markets, score and capacity history, and CSV export. Enterprise adds team seats, weekly data files for all 147,272 sites, the REST API and an MCP server for AI tools.