AUGUSTA (AP) - The Maine Public Utilities Commission on Monday fined Northern Utilities $2 million for a series of safety problems including a pair of home explosions. It also approved the Portland company's acquisition by a New Hampshire utility.

Chairman Sharon Reishus cited numerous probable violations of state and federal safety regulations that were "systemwide and compromised public safety."

All told, nine incidents over the past two years included two home explosions - one each in South Portland and Portland - and a gas leak in Cape Elizabeth. Also, there was an incident in which too much pressure built up in a gas line, leading to several fires in Saco.

"Thankfully no one was injured in any of these incidents," Reishus said. "Vigorous enforcement of safety standards is required and the commission's staff will be vigilant in ensuring that Northern Utilities complies with the commission's order."

The penalties include $1.2 million that the commission will oversee for infrastructure improvements. Another $800,000 is to be paid to the commission.

Also Monday, the commission approved the sale of Northern Utilities, which distributes natural gas to 42,000 customers in Maine and New Hampshire.

Unitil of Hampton, N.H., a utility holding company with 115,000 customers in New Hampshire and Massachusetts, is buying both Northern Utilities and Granite State Gas Transmission from NiSource Inc. for $160 million. Unitil hopes to close the deal next month.