A power control system (PCS) is a control system which electronically limits or controls current or power to stay within defined limits to mitigate overload conditions. PCSs can be thought of as related to energy management systems (EMS), but the functionality of a PCS addressing overload mitigation is critical.
Understanding the application of a PCS
The modernization of homes and businesses in the 21st century is increasingly driven by electrification and smart control systems. A family might be transitioning to an electric vehicle (EV), while a small business installs EV chargers in their parking lot for employees and customers. Homeowners are upgrading their heating and air conditioning systems to electric heat pump-based technology, often supported by utility rebate programs, while installing solar and energy storage systems (ESSs) to help offset utility electrical consumption.
A PCS can enable safety and flexibility in the integration of new technologies, electrification and local generation while making the most of the existing infrastructure in homes, businesses and other types of installation sites.
PCSs represent cutting-edge technology for increasing electrification of homes and buildings by mitigating overload conditions within the electrical distribution equipment through smart control of loads, sources or a combination of both. UL 3141, Outline of Investigation for Power Control Systems, was developed to establish safety requirements to support the integration of a PCS and associated control systems in both new and existing installations. UL Solutions certification information for PCSs can be accessed using UL Product iQ®, which is free to use but requires a one-time registration. Power Control Systems are listed under product category QIJE.
Requirements for the installation and application of EMS
Several articles in the 2023 National Electrical Code® (NEC) address the installation and application of an EMS. 2023 NEC
- Section 750.6 requires an EMS to be listed.
- Section 750.30 addresses when and how a PCS is utilized within specific applications, including but not limited to when PCSs are used to:
- Limit current to a feeder or service (section 220.70)
- Limit current to electric vehicle supply equipment (section 625.42)
- Limit current and loading of busbars and conductors (section 705.13) as discussed with respect to the “NEC 120% rule” outlined in section 705.12.
In the 2026 NEC, PCS listing requirements were moved to a new section, section 130, and PCS specifics are discussed in part II. Additionally, Appendix A was updated to add UL 3141 as an applicable requirement for Article 130.
By addressing NEC-governed, critical-overload conditions and utility-based power export and import limits, UL 3141 supports safer, more reliable modernization of electrical systems. PCS-based control of sources, loads or combinations of both supports safer operation of these devices within the local electric power system while interfacing with existing electrical infrastructure, including utility infrastructure. This helps the accelerated scaling of distributed energy resources, progress toward zero emission targets, grid resiliency and improved customer experiences through safer, modern and intelligent technologies.
For additional information, please download our white paper, “Power Control Systems: Advancing Electrification for New and Existing Infrastructure.”