enclose knob and tube wire
- Thread starter Cjx3
- Start date
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junkhound
Senior Member
- Location
- Renton, WA
- Occupation
- EE, power electronics specialty
also check homeowners insurance -- some dont allow any changes to K&T other than replacement, some will not even insure a house with K&T (e.g state farm in WA)
ptonsparky
Tom
- Occupation
- EC - retired
No kidding. Sometimes it would be easier, cheaper and better to just do the work properly.
Frank DuVal
Senior Member
- Occupation
- Electrical Contractor, Electrical Engineer
I would say to the home owner 'because?" I so no need to do this unless the insulation is bad, then replacement is the proper answer. I've left plenty of properly working K&T in homes in Richmond. More rodent proof than NM! 
James L
Senior Member
- Location
- Kansas Cty, Mo, USA
- Occupation
- Electrician
I agree. Probably long pieces that are bare.I would say to the home owner 'because?" I so no need to do this unless the insulation is bad, then replacement is the proper answer. I've left plenty of properly working K&T in homes in Richmond. More rodent proof than NM!
I had one like that. HVAC guy was getting lit up when he tried crawling across trunk line in attic.
I was asked to ghetto-fy it
Nope. All new. No other options from me.
But I've seen a lot of it in good shape, too
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
I would think that sleeving K&T wire would increase its operating temperature.
James L
Senior Member
- Location
- Kansas Cty, Mo, USA
- Occupation
- Electrician
Maybe not so much if it's covered with insulation.
But maybe
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I would never try to put metallic conduit or EMT around old knob and tube wire.
A proper knob and tube installation will be quite resistant to problems caused by insulation breakdown..
If you are worried about rodent damage, it may be code compliant to use something ilke this over individual wires.
A proper knob and tube installation will be quite resistant to problems caused by insulation breakdown..
If you are worried about rodent damage, it may be code compliant to use something ilke this over individual wires.
ptonsparky
Tom
- Occupation
- EC - retired
It may prevent cat damage but not sure about rodents.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
You may be right.
There are other braided sheaths that specify rodent resistance, but they are not split and would be impossible to install on existing knob and tube.
thanks everyone. I did crawl around and inspect the attic. the splices and insulation are actually quite intact for the age of the house. at most I was thinking of just taping up the splices again to east their mind...
rewire of the attic would be way more work I think than just running pvc split duct or a wire loom of some sort. not to mention far cheaper. again its more about home inspectors causing more concern than truly necessary. love/hate relationship with those guys.
I was worried about potential heat. its not covered in insulation though. so thought it would be acceptable.
rewire of the attic would be way more work I think than just running pvc split duct or a wire loom of some sort. not to mention far cheaper. again its more about home inspectors causing more concern than truly necessary. love/hate relationship with those guys.
I was worried about potential heat. its not covered in insulation though. so thought it would be acceptable.
jmellc
Senior Member
- Location
- Durham, NC
- Occupation
- Facility Maintenance Tech. Licensed Electrician
Most K/T I have seen was pretty far gone already. Thump a wire and watch insulation crumble off. You may be able to use split flex around it but this is a poor band aid. Not worth doing and if something goes wrong, guess who gets the blame.
jmellc
Senior Member
- Location
- Durham, NC
- Occupation
- Facility Maintenance Tech. Licensed Electrician
I saw a very few houses where it was in good shape but they were the exception for sure. Insulation hadn't covered it, loads were moderate. These were nicer old homes that had more circuits than normal, so not much overloading. Work done very well.
Fred B
Senior Member
- Location
- Upstate, NY
- Occupation
- Electrician
Be a "Ghost Buster" get rid of the K&T.
Had a call that started out with kitchen light repair that ended in mostly a rewire. Lights on a K&T with burnt timber around the wire penetration and no boxes, seems to have have been a normal installation method, at least in this house. HO had also complained about ghosts.
The home inspector said the K&T was not in use but was dead wrong, it was live throught the home and badly modified. Found it throughout the house multiple taps to 75% of all the outlets both receptacle and lighting.
Just by chance was using a ticker like is commonly used to determine hot wire and just standing in the middle of room it was going off just as if I was on a hot wire, never ever seen that before.
Shut down first one circuit and lost nearly half the house, no visual sign at panel box of the K&T but found taps onto some of the K&T back into a corner of basement found a lot of bared K&T conductors crossing the basement and some resting onto the heat ducts (at least it was the neutral, wink wink) but not the circuit that shut down the half house. Then found an old fuse box in attic that evidently was the original service panel as it still had the original 3 wire that would come thru the wall. Somewhere it had been tapped onto with NM to provide the power to half the house. Never did find that splice point, but likely an old splice as the circuit left the panel as the old rag wire. Also someone used "blow-in" insulation and encapsulated all the K&T, in the wall and ceiling.
Oh by the way when shutting down of the K&T and getting rid of it, the HO reports "ghosts" also left. (Maybe got a new sign for the side of the truck?)
Had a call that started out with kitchen light repair that ended in mostly a rewire. Lights on a K&T with burnt timber around the wire penetration and no boxes, seems to have have been a normal installation method, at least in this house. HO had also complained about ghosts.
The home inspector said the K&T was not in use but was dead wrong, it was live throught the home and badly modified. Found it throughout the house multiple taps to 75% of all the outlets both receptacle and lighting.
Just by chance was using a ticker like is commonly used to determine hot wire and just standing in the middle of room it was going off just as if I was on a hot wire, never ever seen that before.
Shut down first one circuit and lost nearly half the house, no visual sign at panel box of the K&T but found taps onto some of the K&T back into a corner of basement found a lot of bared K&T conductors crossing the basement and some resting onto the heat ducts (at least it was the neutral, wink wink) but not the circuit that shut down the half house. Then found an old fuse box in attic that evidently was the original service panel as it still had the original 3 wire that would come thru the wall. Somewhere it had been tapped onto with NM to provide the power to half the house. Never did find that splice point, but likely an old splice as the circuit left the panel as the old rag wire. Also someone used "blow-in" insulation and encapsulated all the K&T, in the wall and ceiling.
Oh by the way when shutting down of the K&T and getting rid of it, the HO reports "ghosts" also left. (Maybe got a new sign for the side of the truck?)
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