wet knob and tube

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noon9elec

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Location
Bourne, MA
Greetings
I am currently inspecting an older home (150 yrs), where ice dams created a situation where water entered the home on the third floor and made it was down to the first floor. That being said, it is evident that existing knob and tube wiring had become wet. I would not say inundated with water, but definitely became damp. Does it necessarily mean the knob and tube wiring should be replaced, or should I megger the conductors to ensure the insulation is still good. I personally believe that it will dry out and be fine. Any comments.
 

GoldDigger

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Location
Placerville, CA, USA
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Retired PV System Designer
Wet K&T in wet insulation conducts enough current that alum door frames etc become shock hazards. Fire dept eventually used the house for practice.
However, once it dries the insulation should be about as good as could be expected for its age. Maybe a bit more brittle than otherwise.
The devil is the fact that, for walls at least, you have no way of drying the wire nor confirming that it has fully dried. The portion that is visible in the attic might be OK. The wire between wall and ceiling on lower floors is big question mark, and if you pull the drywall you might as well replace the wire.

FWIW, I would be concerned about mold in those same sealed spaces.
 

electricalist

Senior Member
Location
dallas tx
However, once it dries the insulation should be about as good as could be expected for its age. Maybe a bit more brittle than otherwise.
The devil is the fact that, for walls at least, you have no way of drying the wire nor confirming that it has fully dried. The portion that is visible in the attic might be OK. The wire between wall and ceiling on lower floors is big question mark, and if you pull the drywall you might as well replace the wire.

FWIW, I would be concerned about mold in those same sealed spaces.

I agree, the electrical wires are about 4th on the concern list when there is water damage, framing ,sheetrock and mold then electrical. I think if they wanna know if the wires are good before the others then they probably want to hear ....it looks fine and any one who wants to know after they are sure of the other 3 will say replace the wires even if you say they look brand new.
 
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