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mgillett
insulation with knob and tube wiring

I purchased a 100 year old 3 story home that still has active knob and tube wiring throughout. The attic area (about 60% exposed rafters - 40% floored) is uninsulated. I know I can not place insulation against the wiring, but can I lay bat insulation in between the exposed rafters and not touch the wiring (maybe stay about six inches away and create a barrier ie plywood) or can I lay the insulation boards accross the rafters and then place bat insulation on top of them? (of course this would cover the wiring but not touch it).

Thank you.

Mark in Oklahoma City.

kentvw
Re: insulation with knob and tube wiring

05 NEC Reads:

394.12 (5) Uses not permitted…………….

Hollow spaces of walls, ceilings, and attics where such spaces are insulated by loose, rolled, or foamed-in-place insulating material that envelops the conductors

So then the question becomes; define “envelops”.

It does not say ‘Comes in contact with”.

If I am the inspector I say no you can not.

mgillett
Re: insulation with knob and tube wiring

I define envelop as to cover. So if I do not cover the wire and build a protection barrier so it can never touch or cover the wire - why is that not allowable?

kentvw
Re: insulation with knob and tube wiring

Well, that is just the point……….. Definitions.

The NEC does not give a definition for envelop.

With K&T it is all about heat dissipation and how it relates to deterioration of the insulation.

It might be worth a call to your local electrical inspector’s office to ask your question. I know that here in Denver the inspectors are available in the mornings to field questions and I would imagine that your question has been asked before and that they would have an answer as to how they define envelop and your situation.

mgillett
Re: insulation with knob and tube wiring

thank you I'll call them.

kentvw
Re: insulation with knob and tube wiring

Main Number 405-297-3835
Electrical Inspections 297-2371

Man, you can find ANYTHING on the internet with a couple of mouse clicks! :D :D

canuk
Re: insulation with knob and tube wiring
Quote:

Man, you can find ANYTHING on the internet with a couple of mouse clicks!

There is one person that's a master....:D

Re: insulation with knob and tube wiring

When we purchased our house the insurance company gave us one month the have the knob and tube removed and/or rewire the entire house. We rewired. Rewiring would alleviate the problem and let you sleep better at night.

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