Why are these wires putting burn marks on paper-backed batts?
I’ve seen two houses in the past couple of weeks where wiring is leaving burn marks on paper-backed batts (see pics). I found these because I was snooping around looking for air leaks. I’ve always been told that insulating around wiring is fine if it’s modern Romex type wiring, and that knob and tube is the only thing to watch out for. So finding these two examples is pretty terrifying.
Both of these houses have had panel upgrades in the last 1-3 years. It looks to me like in both cases the heat from the wire is bringing the paper to the ignition point, which then starts to burn the wire itself, rather than the wire burning from the inside out. But I could be wrong. There’s no sign in either case of little furry things nibbling on the wiring.
I’m obviously recommending that an electrician be send to investigate before any additional insulation is added, which would only increase the temperatures around the wiring. Is this something that anybody else has seen? Any theories as to the cause, and/or relative danger?
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