I ran across this yesterday. This only the second time in four years I’ve seen this. It’s a natural gas line installed in a wood burning fireplace. It’s used to “help” get the fire started. It’s a homeowner installed special. I can flag this because there aren’t any safety controls on it. A kid could turn the valve for this gas line, walk away, and maybe the house blows up. Can anyone give me more reasons why this is dangerous? Is this common anywhere in the country?