Electricity saving measures are being applied in Japan starting this week, despite the restart of the first nuclear reactor last weekend, after nearly two months in which Japan was completely nuclear-free.

Consumers served by utilities in central and western Japan have been asked by the authorities to voluntarily reduce consumption by 5 to 15 percent of the summer 2010 levels. The restrictions apply to both households and businesses and are valid through to September 7.

Consumers on the northern island of Hokkaido will enter a similar program on July 23. They will be asked to reduce their consumption by only 7 percent, since there the summer temperatures are lower and air conditioners are used less.

Even if the reductions are not mandatory and there will be no penalties for those who fail to follow them, the government said it would order blackouts if demand reaches 99 percent of supply.

Ohi nuclear plant’s reactor No. 3 returned to operation last weekend despite a deep division in public opinion. Last month, Prime Minister Yoshihiko Noda ordered the restarts of reactors No. 3 and nearby No. 4, saying people’s living standards can’t be maintained without nuclear energy. Many citizens are against a return to nuclear power because of safety fears after the Fukushima accident.