attic insulation knob and tube wiring- foam board?
Jan 27
Is it dangerous to add Foam Board Insulation by knob and tube wiring? How far away would it have to be not to pose a hazard? Or is it possible(and safe) to add some sort of flooring over the wiring and then add insulation? Any info would be great!
I am in the US, a lot of us have it here who live in older houses. We live in a 1920′s victorian.
put fiberglass over it then the foam
knob and tube wiring isn’t,t the best but that is the way it was done then [20,s]
Eco Friendly Polyisocyanurate Rigid Foam Insulation?
Filed under: Foam Board Insulation
put fiberglass over it then the foam
knob and tube wiring isn’t,t the best but that is the way it was done then [20,s]
References :
old timer
The safest thing to do is to rewire your home to bring it up to code (and to make it safe) and then insulate it well. The energy tax credit for insulating materials has increased until 2010.
If yo just add flooring over the wiring, you’ll have a hard time getting to it later and it will probably constitute a fire hazard.
References :
http://www.icanfixupmyhome.com/Insulation_For_Energy_Efficiency.html
Please check the National Electrical Code, you will still find a section that deals with knob and tube wiring systems. The information that your are seeking will be found there. 99% of all tradesmen and electricians do not have a working knowledge of this old system and need to refer to the code book themselves. The section is very specific and I would not trust anyone’s memory in this area not even my own.
References :
30 years as a building Inspector and building official with all of the certifications
Knob and tube is not as bad as everyone wants to believe. Is it more dangerous than modern wiring? Yes. Will your house burst into flame without any reason? No.
The two lines in knob and tube wiring are separated by a distance sufficient to avoid a short between the two wires unless a conductive material comes in contact with, or very close to both lines. I don’t think foam board is a good conductor of electricity, but I could be mistaken. Foil that comes on some forms of foam board IS a good conductor of electricity. Therefore do not use foil wrapped foam board anywhere near knob and tube.
Knob and tube wiring runs inside walls, so it would also be acceptable to box it in and insulate outside the box. See an electrician’s guide to knob and tube wiring for specifics on how to enclose. you’ll want to maintain access in case it needs attention, and you’ll want to be careful about how you build it, leaving the right clearance etc. Nails and screws do conduct electricity.
References :
I am not an electrician
Old knob and tube wiring is totally and completely safe as long as the insulation on the wire is intact. You can install extruded board right next to your conductors without a hazard. I wouldn’t put it directly on top of it, as this would produce a fair amount of strain on your wires.
What most people don’t understand about knob and tube wiring, is that it is actually a safer method than traditional romex. Provided your conductor insulation is in good shape. It seperates your hot and neutral conductors. Whereas romex doesn’t. The only drawback is not having an available grounding conductor.
References :
IBEW Local 252