reply to post by Trillium
Okay, well I will run it down from what I know. The gas is usually shut off at the main line while a house is unoccupied, how ever if a house had just
been purchased it could have been turned on for the new owners to move in.
Now, if while the house was vacant someone broke in to steal the copper, they would steal the copper pipes inside the house, leaving the main gas line
into the home which runs under ground. You could only get so close to the outside of the house with out tearing it apart, before you could even reach
the main line, and I don't think they bury copper pipe because it corrodes to quickly. So, if this was the case(which we can't say for sure at this
time.) when the gas would be turned on from the outside, it would fill the house, unknown to those around the home.
Perhaps, the gas was turned on and someone came back to try to steal more, or the owner came to inspect the home, or an automatic light turned on, or
the water heater cycled, all it would take is a spark for the natural gas to light. Static discharge is enough with the right fuel air mixture.
This can happen in occupied homes as well, all it takes is a small leak, a pilot light going out for instance and time to reach the optimum mixture
and Kaboom. Kid turned on a light, Unplugged an appliance, you turn on the stove, static discharge. Natural gas can be extremely destructive.
A vacant home makes more sense because it would have time to reach the optimum fuel air mixture, before ignition. As well, it would have more empty
space for a uninhibited detonation.
Keep in mind some of the most devistating conventional explosives are fuel air mixture explosives. Examples being
These powerful explosives set off a charge dispersing, gas, liquid or powder fuel into the air, then a secondary explosive igniting the mixture
creating a truly devastating shock wave.
These links were simply trying to help the understanding of how devastating a gas leak explosion can be in the right circumstances.