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Campus Electrical Power System

UC San Diego designed its primary electrical power system for reliability, similar to systems used at many other large California research universities, including UCLA, UC Davis, UC Berkeley, UC Irvine and Stanford.

How the System Works

The campus is connected to the SDG&E utility grid. Power is supplied to campus by three separate SDG&E feeders that merge at a single connection point at the East Campus Switching Station (ECSS). By having three separate SDG&E feeders supply power, a campus power outage will only occur when all three routes for power are interrupted. Although rare, this can happen as the result of a regional power failure or other catastrophic event.

The campus power system also has built in redundancies at multiple levels to reduce the risk of power loss. These redundancies include:

  • Three power transformers capable of delivering power to campus circuits. Two transformers can supply the campus and the third ensures service if one of the first two units is unavailable.
  • Redundant power feeds. There are two electrical connections to each building on campus. Each electrical feeder is rated to carry the full load of the buildings in case one is not available. Most other campuses do not have this level of redundancy at the building level.

power flow diagram

Emergency and Backup Power

Emergency power is the power needed to support life-safety systems (e.g., emergency lighting, fire alarms) in the event of a power outage. All campus buildings have battery-operated systems or backup generators to supply emergency power for life-safety systems.

Backup power, or optional standby power, is the power needed to supply equipment or systems whose failure will not impact life safety. Optional standby power is not required for all buildings.

Improvement Projects

The campus is pursuing several power projects that, when completed, will enhance our ability to respond during any interruptions to the normal electrical power supply. These projects include enhancements to the Central Utility Plant, high-voltage power system, and fuel cell, as well as installation of additional automatic emergency power transfer switches. Facilities Management anticipates completing all projects by summer 2014.

Campus Power Integrity Projects

  • Bypass Stacks at Cogeneration Plant – Steam bypass stacks will enable more rapid starting of the Central Utilities Plant turbines if a power interruption occurs.
  • PMU Monitoring System – Phasor Measurement Units (PMU) or Synchrophasors will monitor the SDG&E grid feed and notify the Central Utilities Plant of potential power interruptions, giving the campus an opportunity to reduce or transfer loads to minimize the potential effects of power disruptions.
  • Resistive Load Bank on Fuel Cell System – The 8 megawatt fuel cell takes approximately eight hours to restart if it trips offline. The resistive load bank will allow it to be restarted quickly if a power loss occurs.
  • Automatic Substation Control System – An Automatic Substation Control System will allow the campus Cogeneration Plant to operate independently during an interruption or loss of SDG&E grid-supplied power.
  • Paralleling Emergency Automatic Transfer Switches – If the campus experiences an interruption of power, the Paralleling Automatic Transfer Switches will enable select campus emergency generators to work in parallel with either the SDG&E or campus grid. These switches will also help simplify periodic emergency system tests, ensure greater reliability, and reduce impacts to the building occupants.

 Campuswide High-Voltage System Renewal Projects

  • Gas switch replacements
  • Power cable replacement
  • Condition analysis and upgrades


Scheduled Maintenance

Normal high-voltage system maintenance requires periodic circuit switching; however, ongoing grid integrity/emergency power projects and new building construction have temporarily increased the need for electrical switching.

Email Notifications

Subscribe to receive Facilities Management Utility/Building System email notifications. (Note: Requires Single Sign-On access and campus network connection or VPN to subscribe.)


Contact John Dilliott, Director, Utilities & Sustainability, (858) 822-2807.