How would you handle this knob and tube situation?

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  #1  
Old 03-24-06, 09:28 AM
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How would you handle this knob and tube situation?

Old house, mostly old wiring. Cannot afford to rewire at this time. A bedroom, living room and a hallway are on one 20A circuit, and it's knob and tube.

It's also raceway, and in bad shape. The raceway was removed with the idea that it would be replaced with new raceway (owner does not wish to break into walls). So there's power coming in from the basement on knob and tube to one receptacle in the bedroom, from which we were planning to run wiremold boxes to the other receptacles on this circuit.

We were going to use #12 to run inside the new raceway. But the knob and tube is #14. The old wiring in the old raceway was also #14.

Given all of these variables, what's the best way to do this project? While I know that rewiring is of course the best solution, it's not an option. If I can't offer any alternatives, the owner is going to just wire it up with #12. He says he did the same thing in his kitchen many years ago, before changing that circuit to NM, and it worked fine. Note that he's kind of a stubborn guy with many, many years of handyman-type experience.

Thank you very much for any help you can offer.
 
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Old 03-24-06, 09:46 AM
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Run away. let him take the responsibility.
 
  #3  
Old 03-24-06, 09:47 AM
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Originally Posted by findtheriver
Old house, mostly old wiring. Cannot afford to rewire at this time. A bedroom, living room and a hallway are on one 20A circuit, and it's knob and tube.
It's probably a 15A circuit that is overfused with a 20A fuse or breaker. Replace this fire hazard with a 15A fuse or breaker. I've never seen or heard of #12 K&T.

So there's power coming in from the basement on knob and tube to one receptacle in the bedroom, from which we were planning to run wiremold boxes to the other receptacles on this circuit.
That is not allowed. K&T is ungrounded wiring, and you are not allowed to extend ungrounded circuits.

Given all of these variables, what's the best way to do this project?
Leave the K&T as is and add new, grounded 20A circuits on #12 wire where you need them. Don't think of it as replacing the K&T, because the K&T layout was designed for a different era; think about where you need circuits and receptacles today. Once you have adequately supplemented the existing K&T with new circuits, disconnect the old runs that are no longer needed.

Don't extend any K&T anywhere; it's old and already overloaded. If you need more receptacles or lights, add new circuits with modern NM-B cable all the way back to the panel box.

EDIT: I didn't realize this wasn't your house. I agree with joed; get out of there unless this upgrade work will be done by a qualified electrician.

...and it worked fine...
What this really means is: "it hasn't caught fire and burned the house down, yet."
 
  #4  
Old 03-24-06, 10:31 AM
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Thanks for the advice. This is for a close friend who's wife is a bit concerned so I told her I'd look into it. I'll print this thread out and show it to him.

By the way, I didn't mean to imply that the knob and tube was #12. It's #14, and there used to be #14 conductors in the raceway that was removed.

The problem is that there is no additional circuit available. He has 100A service and 4 20A breakers. We had this confirmed by two electricians who came out to give estimates. Two kitchen circuits, one bathroom, and the rest on the circuit in question.

Running new NM from the panel would not be too difficult for the receptacles as there is basement access. But the ceiling lights pose an issue. That's a fair amount of fishing wire and breaking into the walls- which, unfortunately, is plaster and lathe.

Is there a way to leave the switches and lights on knob and tube and run romex to the receptacles? Could we install a j-box and branch off to the switches with romex, but leave the switch to light fixture legs as knob and tube?

Thank you for the help.
 
  #5  
Old 03-24-06, 11:17 AM
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First, they don't have ANY 20A K&T or old raceway circuits - if they have 20A breakers or fuses, it's a real fire hazard. Replace them with 15A breakers/fuses immediately.

Second, I respectfully disagree with the poster who said you can't extend ungrounded wiring. Perhaps your local codes don't allow it but the NEC says you can - the splices have to be done according to rather strict rules (the details of which I don't recall at the moment), and must be in boxes. I do emphatically agree with what he said about running new NM for the receptacles.

Your friend's wife is absolutely right to be concerned. I am just finishing a total rewire on my own house (actually, I didn't "re" anything - it's ALL new) in a similar situation. The K&T was overfused, in wooden(!) raceways which were outlawed in the 1920's or so. Heck, we didn't have ANY receptacles on the 2nd floor! It certainly did involve a lot of fishing and removing wall sections and I have yet to repair all the plaster and lath damage I did. BUT, I recognized that with all the modern appliances (window AC, space heater, hair dryers, etc...) we "need" to use on a daily basis, the existing k&t was completely inadequate and a very real danger. If they have more receptacles, they're going to use them - the old wiring then becomes a very real and very big danger.

I know you can extend K&T (in most jurisdictions anyway) but I don't know what the code says about extending k&t FROM new NM. But I think you're on the right track with your last paragraph.

Run #12 NM for the receptacles, then connect (using proper splices, in boxes) the old k&T extending from that. If it's only the lighting that's on the k&t, you won't be drawing much current on it.

Disclaimer - I'm not an electrician but I am an electrical engineer and I did read the NEC and much more besides. I'm *pretty darn sure* about the above but like I said....
 
  #6  
Old 03-24-06, 01:16 PM
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vmweenie,

Thanks for the comments. What you and others are saying about the fire danger makes a lot of sense. I think I might be able to sell the idea of running NM if and only if the switches and lights do not need to be rewired.

This would mean a 20A breaker for the new 12/2 NM-fed receptacles though, right? Would having the switch and light runs remain #14 knob and tube be a problem with the 20A breaker? Assuming the knob and tube can be tied into the new NM wiring.

In my neighborhood there are many 80-100 year old homes and many of them still have knob and tube. I've seen so many splice, connection and extension variations- most if not all not to code, I'm certain. The problem, as an earlier poster mentioned, is that there haven't been any fires or other problems so everyone thinks what they've done is fine. Kind of scary.

Much appreciated.
 
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Old 03-24-06, 01:57 PM
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Originally Posted by vmweenie
I did read the NEC
What edition?

Regardless, you may retract your statement.
The other poster is correct.
You may not install an ungrounded receptacle except to replace an existing one, you may not run a new cable with no EGC, etc.
 
  #8  
Old 03-24-06, 02:19 PM
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Your 100A service is fine for expansion, ours has more on it than that on it.

You cannot use a 20A breaker of #14 wiring. Use a 15A for that.
 
  #9  
Old 03-24-06, 04:20 PM
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The 100A service is coming in on two 50A legs (I think)... so a new box could be obtained with one leg feeding two 15A breakers and one 20A breaker and the other leg feeding two 20A breakers (for the kitchen)?

But if two 20A breakers are required for the kitchen, and one 20A required the bathroom, then we're left using the 15A for the bedroom receptacles... which I don't think will work with new 12/2 romex...

Thanks for the additional feedback.
 
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Old 03-24-06, 04:45 PM
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Originally Posted by findtheriver
The 100A service is coming in on two 50A legs (I think)
No, that's is a 50A service. Could be 60A.

Do you have photos?


> so a new box could be obtained with one leg feeding two 15A breakers
> and one 20A breaker and the other leg feeding two 20A breakers (for the kitchen)?

That's not how the math works.

Are there no other rooms in the house?


> But if two 20A breakers are required for the kitchen,

Are you running the lights off your small appliance circuits?
Or are there no lights in the kitchen?


> and one 20A required the bathroom,
> then we're left using the 15A for the bedroom receptacles...

That's not how the math works.


> which I don't think will work with new 12/2 romex...

Why not?
(Not that it matters.)
 
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Old 03-24-06, 07:25 PM
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Experts correct me if I'm wrong but aren't there special breakers that are sometimes recommended if you can't replace K&T? Arc suppressor breakers IIRC. If he's replacing breakers wouldn't it be best to use these types of breakers?
 
  #12  
Old 03-24-06, 09:13 PM
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bolide,

Thanks once again for your help. A couple of questions:

You wrote:

You may not install an ungrounded receptacle except to replace an existing one...
In this case, that's exactly what the homeowner is doing. He removed the old raceway as it was rusted and covered with gobs of paint and cut the existing #14 wire. So are you saying he could run new raceway and new receptacle boxes since they are replacing the old ones?


No, that's is a 50A service. Could be 60A.

Do you have photos?
I'll try to get some tomorrow.


That's not how the math works.
I'm obviously confused here.


Are there no other rooms in the house?
There's a smaller bedroom that's not really used for anything, but that's it.


Are you running the lights off your small appliance circuits?
Or are there no lights in the kitchen?
The lights are fed by the same circuit as the bedroom and living room- the same circuit which prompted the initial post.


> which I don't think will work with new 12/2 romex...

Why not?
(Not that it matters.)
Good point (both of them).


Thanks very much.
 
  #13  
Old 03-24-06, 11:12 PM
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> are you saying he could run new raceway and new receptacle
> boxes since they are replacing the old ones?

Yes. (I sure hope this answer doesn't get taken out of context by someone else.)
This answer applies to your specific situation.
You can start from the box and run new wire and replace everything as you go.
This has to result in an installation that is at least as safe as the existing installation.


> I'm obviously confused here.

You add concurrent demand load, not the numbers on the breaker handles.
 
  #14  
Old 03-25-06, 10:54 AM
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Thanks for staying with this thread, bolide. Just to sum things up:

> are you saying he could run new raceway and new receptacle
> boxes since they are replacing the old ones?

Yes. (I sure hope this answer doesn't get taken out of context by someone else.)
This answer applies to your specific situation.
You can start from the box and run new wire and replace everything as you go.
This has to result in an installation that is at least as safe as the existing installation.

Okay: So there's 14g knob and tube coming from the panel to feed the bedroom/living room/hallway receptacles and light fixtures. It pops through the floor and feeds one receptacle, from which raceway is run to the other rooms. The knob and tube from the panel to the first receptacle has not been touched.

There were two 14g conductors running in raceway from the first receptacle. This wire was removed along with the old raceway. It will be replaced with new 14g wire and new raceway with no additional receptacles added.

This would not violate code as it's replacing existing non-grounded receptacles with new non-grounded receptacles. The breaker for this circuit, which used to be 20A, should be changed to 15A AFCI.


> I'm obviously confused here.

You add concurrent demand load, not the numbers on the breaker handles.
Makes sense... which is why I've seen 300A worth of breakers in a 200A panel. (Or am I still confused?)

I really appreciate your time and help. I've sort of become the "internet research guy" on my block. While I understand why many urge caution or even "walking away" from this kind of situation, the reality is that some people are going to DIY projects and if I can pass along information to help them I will.

There are many people in their 60s and older who've lived in my neighborhood for many decades if not generations. What's interesting is that nearly all of them have hands-on experience in the trades- they tell me that when they were younger no one could afford to hire out repair work so they did it themselves. This mindset, while admirable, does not always lend itself to keeping up with current codes. But I like how they help one another... even if it often leads to spirited discussions about how things should be done.

Thank you, bolide.
 
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Old 03-25-06, 11:03 AM
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>guy with many, many years of handyman-type experience. <
They are usualy the worst,Know just enough to KILL.

RUN AWAY REALLY REALLY FAST!!!!
Close friends will still sue you, Especialy if it comes down to $ or some other substancial loss.

We must all get a good nights sleep.
 
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