[thackney]

One could expect that the investigators retained by the city will conclude that no one at the city owned utility was at fault.

I expect that to be true. For a house natural gas explosion, the leak would be inside the house, with the customer owned equipment and piping. The NG utility pipes and equipment are outside the house. If their equipment was leaking, the gas would not have built up inside the house. All that assuming it was a NG leak in the first place.

[thackney]

Except for cases like described in post #80.

It can happen, but it normally is not the cause of a house NG explosion.