What is EREC G100?
As the UK transitions to commercial EV fleets, industrial heat pumps, and battery storage, the physical limitations of the national grid have become the primary bottleneck. When a site's electrical demand exceeds its existing grid connection, Distribution Network Operators (DNOs) will block the installation unless costly network reinforcements are paid for.
Engineering Recommendation (EREC) G100 is the regulatory framework that provides a bypass. Published by the Energy Networks Association (ENA), it defines the technical requirements for Customer Limitation Schemes (CLS). It allows sites to safely install equipment that exceeds their grid capacity by electronically guaranteeing they will never breach their agreed limits.
Import vs. Export Limitation
Every commercial connection in the UK has two hard limits defined by the local DNO. G100 Issue 2 governs limitation schemes based on the direction of power flow:
- Active Load Management (ALM): Highly relevant for EV chargers. If total site demand approaches the DNO-agreed Maximum Import Capacity (MIC), the ALM system automatically throttles the chargers down to prevent a breach.
- Export Limitation: Crucial for Solar PV. If a solar array generates more power than the site is allowed to push back into the grid, the scheme instantly curtails the inverters' output to keep export within the legal limit.
The 5-Second Fail-Safe Rule
DNOs do not approve G100 applications based on trust. Installers must submit rigorous engineering reports proving the proposed scheme is fail-safe. If a communication cable is cut or a meter loses power, the system must immediately revert to a predefined safe state. Furthermore, the system must detect an excursion and command the equipment to reduce load within exactly 5 seconds.
Automate Your G100 Reports
Submitting a G100 application is heavily administrative. Historically, proving to a DNO that a site can safely manage its peak demand required expensive bespoke engineering consultations.
Gridcap digitizes and automates this rigorous mathematical modeling. By equipping installers with precise, DNO-ready compliance documentation, we eliminate the guesswork and minimize rejection rates.