Older house wiring puzzle

David Nebenzahl · 2009-09-10T23:43:09+00:00

Have a client with a house built in the '20s, originally knob and tube wired but (partly) converted to more modren wiring methods. Basement ceiling is exposed and where the majority of the house wiring is. Lots of strange, non-standard and some clearly improper wiring exists there: "flying" splices between K&T wiring and NM or armored cable (no junction box), and one place where someone just ran a single insulated wire (THHN or whatever) as a neutral from one place to another. Plus exposed K&T runs going everywhere, one right next to the hot-water shutoff valve.So I've figured out pretty much what goes where and how to replace it (mostly with runs of Romex, since it's not an occupied space).But there's one thing about the old wiring that's puzzling to me. Usually K&T runs are done with pairs of wires (Hot & neutral) running alongside each other, and in most cases that's followed here: a run up into a wall will have a pair of wires going up into the subfloor.But there are a couple of places where a *single wire* is routed up out of the basement into the house above. In these cases, the wires are all hots. No corresponding single neutral wire anywhere nearby. Presumably the neutral side of the circuit is tied to the neutral of another pair of wires.This, of course, makes it difficult to map these circuits, since I can only assume that the neutral connection is made to the neutral wire corresponding to the hot wire. That's my operating assumption, anyhow: my plan is to simply replace these single-wire runs with Romex, using only the black wire. (Hmm, wonder if they make 12-1 Romex w/o ground? Probably not.)Anyone ever seen this situation in an older house?

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bud-- 16 years ago

"Obviously you are too lazy to click on links." Insulating K&T is the subject of the link to the Illinois Dept of Commerce. But you could just read what I posted that came from that link: "No record of hazard was found in the large number of K&T installations that had insulation added around them."

If you knew anything about the NEC you would know it has no intrinsic authority and is in effect only as it is adopted by enforcement jurisdictions.

If you read the Illinois report you would know that many jurisdictions, including 5 entire states, have modified the NEC prohibition on insulation.

Lacking competent sources you attack others. Your level of stupidity is amazing.

Your understanding of the NEC is minimal.

As you consistently ignore, the NEC does not require removal of K&T. A "rewire" can just refeed K&T.

If you read the Illinois report on insulation around K&T you would know that "looking at the record of the code change, it was not based on data substantiating a actual problems."

But why would you want to read - you would just get confused. Zealots don't like conflicting information.

Still missing - *data* that supports your claim that K&T is intrinsically hazardous. Or *authoritative* sources.

Still missing - data that indicates significant hazard from insulation around K&T.

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bob haller 16 years ago

so the NEC prohibition means NOTHING?

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bob haller 16 years ago

heres a interesting link including info on 3 homefires caused by encapsulating K&T with insulation.

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so bud what do you think of the photos of hacked K&T wiring?

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Steve Barker 16 years ago

Bullshit. That's just not true in the US. Don't know about the french.

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Steve Barker 16 years ago

No, they don't regulate insulation practices.

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Steve Barker 16 years ago

That page will not load. Probably being caught by the bullshit filter.

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clare 16 years ago

Hey JERK. The French are Canadien - the rest of us are Canadian - and speek "'merican" just like most of you "yanks" and "rebs"

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clare 16 years ago

Loaded just fine for me. You DO need a reasonably recent vesion of a PDF reader.

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Steve Barker 16 years ago

hmmmm. have version 9.1.3 still no load.

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Steve Barker 16 years ago

OK Asshole. I was just referring to the Canadians as french. duh.

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bob haller 16 years ago

ignore NEC rules home has fire caused by ignorance, contractor is in deep trouble, with major insurance hassles, and likely loose their business.

perhaps his cmputer is aged like K&T:)

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bob haller 16 years ago

that page is interesting stating homes over 40 years old have a electrical fire risk 1.5 times greater than newer homes.

I believe that nearly had a fire here once, from insulation failure in a overhead light that put shower of sparks all over our bed.

replaced all overhead fixtures because of that!!!

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bud-- 16 years ago

Apparently you are too stupid to understand the NEC.

Let me try for at least the 3rd time: The NEC has no intrinsic authority and is in effect only as it is adopted by enforcement jurisdictions. The Illinois report said many jurisdictions, including 5 entire states, have modified the NEC prohibition on insulation.

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bud-- 16 years ago

Approximately 2% of the total fires. There is NO info on the fires.

And "these fires do no constitute a probability sample." In other words, the 2% rate in the reported fires has no general significance because it was not a random sample.

I didn't see much hacked K&T. Fig 3 - *Romex* in and out of a fan with no connectors. No K&T. Fig 5 - only *Romex* is seen, no mention of K&T Fig 7 - an open splice does not appear to involve K&T Fig 8 - open taped splice in extension cord does not include K&T For an article about K&T most of the horror pics weren't K&T. But you probably didn't notice.

My kid's house had hacked wiring, none of it K&T.

Fig 1 shows K&T wiring at a lightning fixture where the insulation has been damaged by heat. This is a fixture problem, not a K&T problem. As I have said, I have seen BX and Romex above light fixtures where the insulation cracked off when you moved the wire. It is why modern light fixtures have temperature ratings for the supply wiring and a lot of fixtures have thermal insulation in the base. So another illustration that is a general problem, not a K&T problem - I am not impressed by the failure in the report to distinguish.

And I am also not impressed by taking volt drop measurements at 20A and comparing to a recommended 5% max drop. Most K&T wiring is #14 designed for 15A.

The report said "properly installed and unaltered K&T wiring is not an inherent fire hazard."

And "insulating over knob and tube wiring, when the wiring is free of problems, is rarely, by itself, a fire problem. However, insulating over wires can be a critical contributing factor to creating a fire hazard when other problems, faults or abuse are present." Most of the 'abuse' in the report was not K&T. Not much of the abuse I have seen has been K&T.

Still missing - *data* that supports your claim that K&T is intrinsically hazardous. This report didn't support your claim.

Still missing - data that indicates significant hazard from insulation around K&T. Didn't see that in the report either.

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bob haller 16 years ago

GOOD you at least read the link, progress.

the trouble with K&T the connections are all buried inside walls etc no boxes. So its impossible to inspect properly and if you open walls you might as well replace it, and upgrade to more than one outlet per room:)

do ask the 3 people who had home fires from encapsulating K&T in insulation wether its a fire hazard.......

and stand back they might want to throw something at you.

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clare 16 years ago

Don't be an ignorant ass about it.

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bud-- 16 years ago

You're a real idiot.

If you actually read your source you would have found it does not agree with you.

Your source said "properly installed and unaltered K&T wiring is not an inherent fire hazard." That contradicts to what you say.

The problems shown in your source were almost all not identified as involving K&T wiring.

Your source said the data did not have statistical significance.

The "Illinois" report found no record of hazard in the large number of K&T installations that had insulation added around them.

Many jurisdictions, including 5 states, allow insulating around K&T.

Your source insulated around much of the K&T wiring.

Still missing - *data* that indicates significant hazard from insulation around K&T.

Still missing - *data* that supports your claim that K&T is intrinsically hazardous. Your source directly contradicts you.

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bob haller 16 years ago

statisticall significant is 100% for those who had fire from insulating K&T the article clearly states this occured

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bob haller 16 years ago

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In looking into the NEC this report clearly indicates that although the NEC isnt a national law anyone who desnt follow its rules are liable if a fire occurs.

so nearly all juristictions have adopted these rules as local laws.

and if bud happily insulates over K&T to make a few bucks, and a fire occurs bud will be liable in a court of law for his stupidity.

ultimately who doing any home repairs wants the risk of a fire? or to be civily or criminally liable if a fire occurs? or someone gets hurt or worse?

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trader4 16 years ago

From what I have seen, it's not common to find "unaltered" K&T wiring. A house wired to what was common and needed 70+ years ago couldn't meet the needs of what is minimal in homes today. Today homes need more outlets, more capacity, more fixtures, etc. Things like a simple window AC unit that you can buy for $100 didn't exit then. So, it's common for these K&T systems to have been added on to, expanded, partially replaced, etc with a variety of more modern wiring. And a lot of that work was done by the homeowner or some hack so that you have dangling splices, no junction boxes, etc.

I think it's unfair to accuse the insurance companies of "redlining" because they have concerns about K & T wiring and demand that they prove K&T itself is the problem. If it is in fact unaltered and still used as intended, it may still be safe. But in practice, it's rarely left alone and still used the same way. Personally, I would not trust it in any home I was going to live in. Is that redlining?

Would it make you happier if instead of saying they won't insure homes with K&T insurance companies instead said they won't insure homes older than 70+ years if they still have the existing wiring ?

Bud, you jump on Bob for not giving you any relevant authority or data. In the case of insulation around K&T, he has showed that the NEC doesn't allow it. Yet, when he does, your response is many jurisdictions allow insulating around it. I don't know about you, but I'd give more credibility to the NEC before the local electrical inspector, building dept, etc.

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