Germans could overload their power grid as they switch to inefficient electric heaters in an attempt to avoid gas shortages this winter, utilities warned in an article published on Sunday.

Households have been stocking up on electric fan heaters, sales figures show, amid fears that Russia could cut or further limit gas supplies in the wake of its war in Ukraine.

The managing director of the German association of energy and water utilities, BDEW, told daily Handelsblatt that customers could be left with even heftier power bills if they do not use the devices sparingly. “And they can overburden the power grids, for instance when many households switch on their fan heaters in one part of town at the same time,” BDEW director Kerstin Andreae said.

She said she understood people’s fears of cold homes, but some of the coping mechanisms could backfire.

Germany is scrambling to support homes and industries burdened by a surge in energy prices after Russia halted supplies through the Nord Stream 1 natural gas pipeline.