Knob and tube

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johnsmith

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I'm getting conflicting information from "experts" in my local area, plus a review of these boards of what the code reference is for Knob and tube wiring.

One electrician tells me its Article 324, and that you can wire a new house using knob and tube.

A city inspector says that its Article 394, and it's allowed for exisiting homes provided it's not buried in insulation 394-12), and you can extend existing K&T if you do it right.

Which code is it?
Who is right on the new house issue?

Cheers!
 
Re: Knob and tube

Thanks

Being that I don't have an NEC code book, would you mind elaborating on what 394.10 says. And how come an electrician is saying Article 324 - is that old code?

Cheers!!
 
Re: Knob and tube

From the 2002 NEC:
]quote]394.10 Uses Permitted.
Concealed knob-and-tube wiring shall be permitted to be installed in the hollow spaces of walls and ceilings or in unfinished attics and roof spaces as provided in 394.23 only as follows:
(1) For extensions of existing installations
(2) Elsewhere by special permission[/quote]
 
Re: Knob and tube

So, you'd have to get "special permission" for a new house...why the heck would anyone give permission to use this old stuff!!

What about the reference to Article 324? Is that old code, or unrelated code?

cheers!
 
Re: Knob and tube

Originally posted by johnsmith:
So, you'd have to get "special permission" for a new house...why the heck would anyone give permission to use this old stuff!!
Click to expand...
I wouldn't allow it.

What about the reference to Article 324? Is that old code, or unrelated code?
cheers!
Click to expand...
I'm not sure if that article covered K&T in a previous edition. In the 2002 article 324 covers flat conductor cable, which is quite different than concealed knob and tube. :)
 
Re: Knob and tube

In the 99 NEC 324 was K & T

Roger
 
Re: Knob and tube

Originally posted by johnsmith:
So, you'd have to get "special permission" for a new house...why the heck would anyone give permission to use this old stuff!!
Click to expand...
Why would anybody be seeking permission?
 
Re: Knob and tube

Jim maybe at the 5 + 10 cent store ...... :D
 
Re: Knob and tube

In Cleveland you will find a lot of Knob & Tube wiring. By city codes, you cannot extend any K&T wiring. When rewiring houses you can leave existing k&t to switches,lights,and recept except in kitchens. Must replace k&t from where it enters the basement from the 1st floor to panel.(no k&t in basement.) Any additional recept shall consist of new wiring.(NM) You must use loom when entering j-boxes. After wiring these houses for about ten years I became a pro with k&t. Also FPE served as mains to feed the fuse boxes,scarrrrry. :D
 
Re: Knob and tube

Rewiring old K&T houses can be fun.I take them as a challenge to do little or no damage.After first 1 or 2 you learn tricks.But they are rewired in romex not K and T.Why would anyone try to use that system today ?

[ July 18, 2004, 05:00 PM: Message edited by: jimwalker ]
 
Re: Knob and tube

In terms of actual electrical safety, I'd take knob and tube in original condition over NM any day with the exception of the grounding issue.
Don
 
Re: Knob and tube

One of the things that always has hung in the back of my mind when thinking about the old K&T that I repaired, I never surveyed the full extent of the load on the neutrals. I haven't done any in a long time except to help other electricians, aand they didn't survey the neutrals either. It seems that there was always something nagging me about those wire runs, as they were always showing up as the neutral for oddball outlets.

now, I would want to survey the full extent of all loads before I assumed that the wiring was safe at all.

I think there are actually pluses to K&T but they are far outweighed by the hazards. The one thing that seems good is that there is a lesser chance of arcing with a ground or to the neutral (fires) but the wire can easily become compromised so thst it will not carry load (knick or contacting break) and that will arc as well.

I stopped giving fixed prices to repair any old wiring. I just tired of that feeling i got when in the light box was 1" of overheated K&T in a real victorian plaster ceiling.

paul
 
Re: Knob and tube

I have rewired k+t houses by the dozen's . In my area there is quite alot of salt in the air from the constant large surf. What I see frequently is the old cloth insulation worn away in long sections between the knobs. The copper conductors have coroded away problably due to the salt content, and we get alot of service repair work because they get broken or burn thru in the middle of the run between knobs under houses. Romex has its faults, but in my opinion pound for pound it is much better to replace the old k+t with new romex.
 
Re: Knob and tube

The thing homeowners love about the K&T is how it makes a great closet rod near the laundry machines in the basement. :D LOL

Saw that one just the other day, and of course it was the hot.
 
Re: Knob and tube

Well, thanks for the amazing feedback. Much appreciated.

We found that our active K&T in the attic was buried in 6 inches of sawdust insulation - presumably an NEC code violation for K&T! There was in-line splices using electrician's tape up there too.

Cheers!
 
Re: Knob and tube

Why don't they just soak them wires in gasoline ? Had customer on remodel couple years back that ended up rewiring cause of insulation on
K & T.Does anyone ever think to sue insulation companies that do this ?
 
Re: Knob and tube

Jim, I would bet only 1 in a 1000 insulation companys even know this is a hazard. Couple fires/lawsuits could fix that.
 
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