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National Grid System Operator raises Urgent Modification (GC143) with implementation date of 07th May

(ahead of this weekend’s Bank Holiday – a period of low demand with significant operational risk)

National Grid


This modification sets out that under emergency conditions and as a last resort the Electricity System Operator (ESO) may instruct a Distribution Network Operator (DNO) to disconnect embedded generators connected to its system. The requirement for this is due to the unprecedented societal changes brought about by the COVID-19 pandemic which has led to demands out-turning up to 20% lower than predicted.

At present in the Grid Code there is a process for the ESO to instruct DNOs to take demand control actions but there is not the same detailed ability for the ESO to instruct Distribution System Operators (DSOs) to disconnect embedded generation. If this change is not made, National Grid maintain that there is a risk of disruption to security of supply during unprecedented low demand periods caused by the COVID-19 pandemic. National Grid state that this is a rapidly developing situation and could not have been anticipated so the proposed change sets out the ability of the ESO to instruct DNOs to disconnect embedded generation as required in an emergency situation and as a last resort. 

Currently in the Grid Code the ability of the ESO to make such instructions is ambiguous and would potentially leave DNOs in a position that they would feel exposed to legal risk; therefore, the proposed changes seek to clarify these arrangements.

The deadline for consultation responses is close of business on 05th May.

The consultation document can be found at the following link: