The gas lines here used a different system than most of the US. The normal way is for a high pressure line to run to a regulator at each house. That regulator t

The gas lines here used a different system than most of the US. The normal way is for a high pressure line to run to a regulator at each house. That regulator then controls a low pressure for that house alone. This gas company however had low pressure distribution lines connected to thousands of houses, each controlled by a single regulator and operating at 0.5 psi. While replacing a section of distribution piping, workers left the pressure sensors the regulator used attached to the old piping. This caused the regulator to continue raising the pressure in the new piping since as it was fed data that pressure in the old piping was falling to zero. The fault was with the work plan order, which the workers on the scene were following exactly, and with a system design that allowed a single point of failure to burn a hundred houses. The gas company will be switching this area over to a more normal setup with regulators at each house.