Britain's National Grid warns of system tightness for Wednesday

OSLO, Nov 4 (Reuters) - Britain’s National Grid has send out an electricity margin notice (EMN) for Wednesday evening as it seeks to increase spare capacity amid a tight power system.

National Grid is responsible for ensuring supply and demand are balanced in Britain’s energy systems.

“While we have enough generation to meet demand, we’ve issued an electricity margin notice (EMN) for tomorrow evening,” the company said on Twitter late on Tuesday.

This was a routine signal it sent to the market to indicate that it would like a larger cushion of spare capacity, it added.

For the period from 1630 to 1830 GMT the system margin was expected to show a shortfall of 740 megawatts, excluding any available balancing reserves, a system warning message specified.

Earlier on Tuesday, it had issued another tweet to warn of tight margins on the electricity system on Wednesday due to low renewable power output and concerns over sufficient availability of generators for periods of high demand.

The grid has a number of tools to help balance supply and demand and paid power producers such as nuclear generator EDF to reduce output over the summer when demand was weak.

British wholesale electricity prices for day-ahead delivery rose around 26% on Monday to 52.50 pounds per megawatt hour. (Reporting by Nora Buli, editing by Louise Heavens)