One of the state’s largest electric utilities faces a $10 million federal fine.

Federal authorities charge Duke Energy, a potential buyer for debt-ridden San-tee Cooper, of serious, pervasive violations of rules to protect the nation’s electric system from attacks.

A successful cyber attack could cause enormous loss of life, especially if it happened during extreme weather such as last week’s record-low temperatures.

According to newly released documents in a regulatory filing, some violations lasted for years and others apparently are continuing.

Investigators have referred a settlement agreement to the Federal Energy Regulatory Commission for approval, according to the filing by the North American Electric Reliability Corp., The Wall Street Journal reported.

The fine is a fraction of what the law allows.

Duke operates gas and electric utilities here and in 6 other states and has more than $138 billion in assets and 29,000 employees.

Its security should be top notch, industry experts say.

Federal officials say Duke broke 127 safety rules, a serious risk to the security and reliability of the eastern interconnection, the web of electric utilities east of the Rockies that furnish electricity to most Americans.

For 6 months engineers weren’t alerted about attempted hacks, the newly released documents show.