Replacing knob and tube. Do i need to bring the house up to code?

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rhovee

Member
I am pretty sure the answer is a "no", but i have to ask anyway. I have a job i am bidding and the owner wants all the knob and tube ripped out and replaced. Those are always hard jobs to bid. But i started second guessing myself if i would be required to bring the house up to code as far as spacing goes and dedicated circuits in the kitchen? No outlets outside...stuff like that. What has been some of your guy's experience?
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
I am pretty sure the answer is a "no", but i have to ask anyway. I have a job i am bidding and the owner wants all the knob and tube ripped out and replaced. Those are always hard jobs to bid. But i started second guessing myself if i would be required to bring the house up to code as far as spacing goes and dedicated circuits in the kitchen? No outlets outside...stuff like that. What has been some of your guy's experience?

Regardless if the job is inspected or not, if you are rewiring the place why would you NOT bring the complete electrical up code?
 

John120/240

Senior Member
Location
Olathe, Kansas
What Edward said. How do you plan to run your wires ? Fish or open up the walls ? With knob & tube goofy wiring methods were employed vs today's methods. With Knob & tube you know GFCI's, smoke dectors, fart fans, outlet spacing etc, etc were all unheard of practices. Remove the lath & plaster, then wire like a new home.
 

rhovee

Member
The owner lives in the house and asked me to only replace the existing wiring. Since they live there, they weren't wanting to have a big mess of lathe and plaster and the patching that follows. I agree with both of you, but the owner wouldn't go for it. I mentioned it but it was a no go.
 

John120/240

Senior Member
Location
Olathe, Kansas
Knob & Tube also suggest that it is time for a new modern panel with breakers vs fuses. Grounding is likely not up to code. While you are there sell them a new service, that brings the power company & city inspector to the job. When these folks sell the home a modern electrical system is a plus as opposed to Knob & Tube.
 

PetrosA

Senior Member
Around here knob and tube often gets upgraded to one outlet per wall regardless of room size, and one switch for something. They can't make you bring it up to code for wall spacing until you expose the studs or brick, and most AHJs around here won't force anybody to go through the cost a complete upgrade would force on the homeowner unless the building is being gutted. In an occupied home even the basic upgrade to one outlet per wall is going to mean intense havoc for the occupants - floor cut up, furniture moved from room to room, holes to patch, multiple rooms in use to wire in lights, etc. and the costs can be huge compared to wiring an unoccupied building with carpenters and plasterers/drywallers following you around. A few years back I looked at rewiring a 3 story Victorian here in Lancaster to the one-per-wall standard, approximately 3500 sq. ft, occupied, with high end trim work and plaster. Considering that I had to do it with five people living there it would have to be almost totally clean, dustless work. I figured it could easily run into multiple months of work for one guy with moving furniture etc., and the not-to-exceed price was prohibitive since the number of bases to cover was astronomical (potential damage to plaster, woodwork, floors, etc.).

Compare that to a 1500 sq. ft. 1907 house that I'm working on now. Two days channeling the walls in the kitchen and rough-in (all four walls are plaster-on-brick), another day to rough in a new bath and bedroom closet, and maybe a few more days to finish three-per-room without eliminating the K+T lights plus trimming out. Probably under $5k total, but it's a bloody mess in there now and my wife made me take my clothes off at the door when I came home ;)
 

edlee

Senior Member
I am pretty sure the answer is a "no", but i have to ask anyway. I have a job i am bidding and the owner wants all the knob and tube ripped out and replaced. Those are always hard jobs to bid. But i started second guessing myself if i would be required to bring the house up to code as far as spacing goes and dedicated circuits in the kitchen? No outlets outside...stuff like that. What has been some of your guy's experience?

If the owner wants the knob and tube replaced, then you can do that and be finished with the job.

The new wiring will have to have the appropriate arc-fault protection, gfi protection and circuit layout but there is no requirement that any new outlets be added unless walls are opened up. The service panel of course will have to be able to handle the new circuits/AF breakers.

I am doing one know where for budget reasons we aren't upgrading the service but instead we are adding a small sub-panel for the new circuits.
 

GerryB

Senior Member
I am pretty sure the answer is a "no", but i have to ask anyway. I have a job i am bidding and the owner wants all the knob and tube ripped out and replaced. Those are always hard jobs to bid. But i started second guessing myself if i would be required to bring the house up to code as far as spacing goes and dedicated circuits in the kitchen? No outlets outside...stuff like that. What has been some of your guy's experience?
Do you mean rip it out where it's accessible like the basement and attic or are you going into lights, switch boxes, etc? What I have done on a few K&T jobs is rip out what's accessible and box it close to the walls, (all that's required by code), change old outlets to new 2-prong or gfi, and suggest running some new circuits as needed, like the kitchen, etc.
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
What has been some of your guy's experience?
Working in the Twin Cities of Minnesota, I have experienced a lot of different "jurisdictions." In my area, your question is understood to not be answerable from the NEC. Rather, one must look to any local ordinance that covers maintenance to existing dwelling wiring systems.

Most of the jurisdictions I work in don't have any local ordinance governing existing dwelling electrical system maintenance, therefore, the only rules are that of the NEC. And that is, simply, one rebuilds each K&T surface penetration to current NEC requirements, nothing more. If the K&T includes a K&T fuse box, then, yes, replace it, but otherwise, one is only working on a branch circuit and it's more modern overcurrent protective device.

When the walls are not opened, per room, to 50% or more exposed framing, one simply rewires each existing K&T receptacle, light, or switch location complying with the current NEC. The end result is an increase in safety, even though the number of receptacles, lights and switches has not changed. This is seen, by the Authority Having Jurisdiction, as good.
 

mwm1752

Senior Member
Location
Aspen, Colo
While it is a good idea to replace knob & tube it is not required unless the AHJ considers it a life safety issue. Tell your owner -- Really what's to worry, cloth insulation, open conductor connections & more that a century of rodent damage. :happyyes: NEC 394.10
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
While it is a good idea to replace knob & tube it is not required unless the AHJ considers it a life safety issue. Tell your owner -- Really what's to worry, cloth insulation, open conductor connections & more that a century of rodent damage. :happyyes: NEC 394.10
Interesting that you cite "Uses Permitted".

I'd have gone to 394.12(5):
394.12 Uses Not Permitted. Concealed knob-and-tube wiring shall not be used in the following:
(5) Hollow spaces of walls, ceilings, and attics where such spaces are insulated by loose, rolled, or foamed-inplace insulating material that envelops the conductors​
394.12, although only in the Code since the late Eighties, has become understood by most insulation installers to prohibit them from adding insulation to an existing building cavity if they can reasonably suspect that K&T is already within that cavity. So, energy conservation tends to cause the interest of an owner asking me to remove K&T.

Also, loyalty to a particular insurance scheme will result in the building owner accepting a directive that all the K&T must be removed.

In the Twin Cities inner city, there is a HUGE installed base of fully insulated K&T still happily in service. As long as it is not overloaded, nor having a history of overloading, and the system has been maintained, within reason, the existing K&T installations will continue to have a long life, in my opinion.
 

macmikeman

Senior Member
Around here, they call this operation ''rewiring'' and yes if you take out a permit you will be required to bring whatever area's you affect to code spacing and afci and other code rules. For me, once I start messing with knob and tube, I either get paid to rip it all out, or else I pass on the job. Liability and cover my butt. I dislike the job of rewiring, it is nasty , rodent carcass , hot attic work.
 

mwm1752

Senior Member
Location
Aspen, Colo
Interesting that you cite "Uses Permitted".

I don't think the OP is discussing rewiring with knob & tube just leave the existing in place that is not demo'd.. We are talking NEC requirements not the I said so code. Don't misinterprete my code comments as personal beliefs. I would also suggest to eliminate all K&T. It is the owner or AHJ that needs enough evidence to convince for rewiring.
Personally, I do not like when others tell me how to spend my hard earned cash. (as if I had any extra):happysad:
 

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
I don't think the OP is discussing rewiring with knob & tube just leave the existing in place that is not demo'd..
I read the OP differently. I read that the K&T is to be removed and replaced with modern Chapter 3 methods and that this raised a "second guessed" question about whether doing so to the K&T required doing additional improvements to wiring (absent or existing) that is not part of the original K&T. For example, if the Living Room K&T light and two receptacles are converted to NM-B light and two receptacles, does the Kitchen have to have two small appliance branch circuits added?

I have a job i am bidding and the owner wants all the knob and tube ripped out and replaced. Those are always hard jobs to bid. But i started second guessing myself if i would be required to bring the house up to code as far as spacing goes and dedicated circuits in the kitchen? No outlets outside...stuff like that. What has been some of your guy's experience?
Now, if one of the OP's original K&T receptacle is in the Kitchen at a counter, then, by the 2014 NEC that would regulate the rewire, that rewired Kitchen counter receptacle would be AFCI, GFCI, TR and on a small appliance branch circuit. BUT, if the Kitchen counter receptacle wasn't on the K&T to be rewired, no alteration of the existing install would be required by virtue of the K&T removal and replacement elsewhere in the dwelling.
 

GerryB

Senior Member
Around here, they call this operation ''rewiring'' and yes if you take out a permit you will be required to bring whatever area's you affect to code spacing and afci and other code rules. For me, once I start messing with knob and tube, I either get paid to rip it all out, or else I pass on the job. Liability and cover my butt. I dislike the job of rewiring, it is nasty , rodent carcass , hot attic work.

It is very nasty work and if the HO expects it done with no mess (like the op stated) I would say next to impossible. Running new wires to old boxes is doable in interior walls, open attic and basement, two guys, (still not easy), but how do you fish from say the front door switch box to the attic. That's why I suggest leave it alone and add new circuits in crucial areas. Around here if you pull a permit for say a service upgrade and there was exposed K&T in the basement the inspector would make you remove it and box it near where it enters the wall. All that accomplishes though is to make the basement look better.
 

Carultch

Senior Member
Location
Massachusetts
I am pretty sure the answer is a "no", but i have to ask anyway. I have a job i am bidding and the owner wants all the knob and tube ripped out and replaced. Those are always hard jobs to bid. But i started second guessing myself if i would be required to bring the house up to code as far as spacing goes and dedicated circuits in the kitchen? No outlets outside...stuff like that. What has been some of your guy's experience?

Knob and tube is another example, where it is something that was OK a long time ago, but isn't OK today. While it isn't something you necessarily have to fix today just to pass inspection on unrelated work, there are other reasons why you might want to fix it, such as insurance.

In general, your existing electrical work can remain compliant with the code that it was once compliant with. However, that which was always wrong, cannot continue to remain wrong.

For instance, there are no AFCI's in the house because it was built 50 years ago....fair enough,don't put them in.

However, if there is a problem such as a panelboard covered by a shelving system, that is something that was never OK. And you can be responsible for relocating it, because it never would be permitted by the NEC.
 

flipperdave

New User
Location
okc, ok
insuring knob and tube

insuring knob and tube

I talked with my insurance agent from Farmers. He said that they would not insure a home with knob and tube, although they do not ask if its in the house. If the house burns down due to a wiring issue, it would not be covered.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
While it is a good idea to replace knob & tube it is not required unless the AHJ considers it a life safety issue. Tell your owner -- Really what's to worry, cloth insulation, open conductor connections & more that a century of rodent damage. :happyyes: NEC 394.10
If the knob an tube has not been modified and is not buried in insulation, other than the fact that it doesn't have an EGC, it is my opinion that it is safer than NM. Note that is is rare to find K&T in its unmodified original condition. Most of the problems with that wiring method have come from improper modifications.
 

Pharon

Senior Member
Location
MA
I'm of the opinion that branch circuits with EGC's are always safer than those without. And I'll choose today's Romex insulation over 90 year old cloth K&T every day of the week, even if it's never been modified.
 

iwire

Moderator
Staff member
Location
Massachusetts
I'm of the opinion that branch circuits with EGC's are always safer than those without.

Consider this.

In most wood framed homes bringing the EGC into say the living room provides the other conductor needed to electrocute the occupant.

Very few people, even less home occupants will receive a line to line or line to neutral shock and an EGC will not prevent either of those types of shocks.

Most home occupants that get a shock will be shocked line to ground and if there is no ground to contact that possibility is illuminated.

Now of course, go into a room with metal plumbing and things change a bit.

I not really anti-EGC but I think it is wise to look at things from all perspectives and not just assume an EGC makes a room safer.


As far as K&T, they do not run side by side like a cable so even if you they are bare they will not short and are unlikely to cause a fire due to the ceramic knobs and tubes. Can we say that about how we run NM?

Overheat NM and it will either short or being directly against wood start a fire.

Again, I am not anti-NM just looking at things from all sides instead of assuming new is always better.
 
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