Really old house wiring -- safe?

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Old 11-12-07, 11:58 AM
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Question Really old house wiring -- safe?

I inherited a very old house -- rental property. Built in 1928. Many of the electrical fixtures appear to be original to the house. The wiring has me worried. The insulation appears to be something like braided cotton? When I remove a light switch or outlet (with the circuit OFF, off course), that's what I see. The insulation seems to be in good shape, I;ve just never seen this before. Also, where wires are joined in a junction box -- where I would expect to see plastic wire nuts -- instead of wire nuts, it looks like some sort of fabric wrap or fabric tape that holds the wires together. The tape is very stiff, like perhaps it was coated with shellac or something when it was installed -- it doesn't peel off easily, in fact I think I would have to cut it off with a sharp knife (if I wanted to remove it).

Is anyone familiar with this type of house wiring? Is it considered safe? Obviously the house has been there since 1928 and hasn't burnt down. Should I leave it alone? Or is it unsafe and should be replaced with modern Romex? Or replace the taped joints with modern wire nuts?

At one point, a relative had a new breaker box installed -- all modern circuit breakers, replaced the original fuse box.

The house has been in the family since it was built, and I am quite sure that no one has altered the wiring, it is the original wiring done in 1928 (except for the new circuit breaker box). The man who built the house had an excellent reputation in his time, so I assume this was considered good practice when it was built. This was NOT done by some half-a@$'ed amateur.

Would love to hear from anyone who has specific knowledge of this kind of wiring & insulation. Thanks!

Mikaman
 
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Old 11-12-07, 01:10 PM
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I strongly suggest that you buy a copy of the book "Your Old Wiring" by David Shapiro. This book steps through things such as evaluating the old wiring, determining if you can make repairs or of you need to have a professional make repairs, etc. There are pictures of different types of wiring, and descriptions of what you can expect in terms of damage.

It sounds to me like you have cloth covered rubber insulated wires. This could either be 'knob and tube' wiring (separate wires on insulating posts), 'BX' wiring (a cable in metal armor) or even NM cable (this looks like cloth covered 'Romex'). The biggest problem with this insulation is that it gets brittle and cracks when disturbed, especially where heated. You go to replace a light fixture, and find that all of the wire in the junction box is brittle and falls apart in your hands.

The splices that describe are probably soldered and taped. Left alone they are as good or better than wirenut splices.

IMHO you will probably have new receptacle circuits added to accommodate modern loads (computers, air conditioners, etc), but may be able to get away with leaving the old wiring alone and intact, and simply fishing new circuits.

-Jon
 
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Old 11-12-07, 05:24 PM
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Where I live you can't get house insurance if you have 'knob and tube' wiring. To get insurance, you need to update the wiring.
 
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Old 11-12-07, 05:42 PM
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My advice to anyone who has knob and tube wiring is to replace it. I cant count the number of times I've seen K &T wiring left in an attic that people thought was fine only to see the insulation crumble off the second it was touched.

I'm sure I dont need to tell you what no insulation on wires running through an attic means. Quite an obvious safety hazzard.

I would do as suggested and run new circuits for heavy loads and appliances (priority) and gradually phase out the K&T wiring over time.
 
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Old 11-12-07, 07:19 PM
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Tip:

I have quite a bit of experience with crunchy wires up in light boxes with the cloth insulated/friction-type tape method of joinery the OP poster describes. Many tenants put in 100 watt light bulbs and cook the heck out of those wires up in the ceiling box. The wires will hardly even bend anymore up there as they have literally cooked themselves into the position they are in. I like to try to not even disturb it at all. I will simply clip the wires of the old light fixture itself and wire nut the new light fixture wires directly to them, without ever pulling down on crunchy wires packed in the box. Just by flexing those wires ever so slightly can open up the insulation and you have to tape where it cracked.

Then I'll tell tenants that WE will replace the bulbs when they burn out and put in new CFL's to reduce odds of tenants who haven't a clue from making sockets come loose, causing light fixture to come loose from the ceiling box, dropping often heavy lens covers, etc. And we know that the CFL's up inside are less hot and is less hard on the wiring above and hence safer.
 
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Old 11-12-07, 08:14 PM
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I'd opt for an electrical inspection for safety of the property and those who live there.

For some info on knob and tube wiring: http://en.wikipedia.org/wiki/Knob_and_tube_wiring

"1920's wiring consisted of separate wires suspended on ceramic knobs, and where they passed through framing, the hole was lined with a ceramic tube, thus giving the name "knob and tube wiring". It works well as long as not subject to physical damage or blown in insulation in the attic." http://www.kuffelcreek.com/1920's_construction.htm
 
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Old 11-12-07, 10:31 PM
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Couple of things:

- We do not know this is knob and tube wiring for sure. The year 1928 sure screams it but that's all. Insulation described as "braided cotton" could just as easily be applied to slightly more modern fabric-covered NM as well, no? MikaMan- surefire way to tell is to see if you have such knobs in your basement AND they are still being used.

- There is nothing wrong with K&T wiring as long as it is not disturbed. As this is a point of controversy I'll leave it at that.

- In the K&T days, people were scared to death of electricity, and thus the workmanship was MUCH better.
 
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Old 11-13-07, 05:15 AM
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This type of insulation, and tape was commonly used up to the 50's. The wires are "safe" until bended, then the old insulation will brake, and it may be unsafe next time it is touched. If you want to use it as a museum, it could be anidea.

If it was my house, I had started rewiring, first; kitchen, bathroom and rooms with activity, children, water etc.

dsk
 
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Old 11-13-07, 08:28 AM
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NOT knob & tube

Thanks for all the helpful replies. It is definitely NOT knob & tube. I know what knob & tube is, I've dealt with it before -- this is not k&t. Based on Winnie's description, I believe it is NM. I'm also familiar with BX, and right now (I'm not at the house), I don't recall seeing that. Also, Winnie's description of soldered & taped junctions sounds correct to me. I haven't unwrapped the tape from any to check.

Sounds like the best thing for me to do, is leave it alone. The realtor suggested replacing a lot of the fixtures, installing GFI in the bathroom & kitchen, replacing switches & outlets & covers to get rid of old ones that have been painted over (aesthetics) ... but it sounds like I'd be asking for trouble by disturbing the wiring to do that stuff.

I would think it would be a huge headache to try to re-wire the entire house -- two story, two-family house. I can't imagine how one would fish wires through the walls, to replace this stuff with modern Romex. The walls (plaster over lath) are in good shape and I wouldn't want to cut intot he walls all over the place to fish new wires. Think I'll leave it alone.

Mikaman
 
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Old 11-13-07, 10:28 AM
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One thought based on personal experience:

Consider checking the walls in each room very thoroughly to see if any old lighting has been "decommissioned" and patched over. My house was built in 1923 with K&T, and at some point in its history, someone elected to change the lighting scheme in several rooms. As part of the process, they removed some lights and, presumably in order to keep the circuit alive for the retained lighting, spliced the wires and buried them in the walls.

I discovered the first one when working on a small wiring project, and that led to a whole-house inspection that uncovered several others. That, in turn, led me to a complete rewire project. It was a lot of work, but well worth it because I found charring in a few places.

My situation may be rare, but if I move into another home (even a more modern one), I will be on the lookout for this sort of thing.
 
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Old 11-13-07, 03:05 PM
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Originally Posted by core View Post
- In the K&T days, people were scared to death of electricity, and thus the workmanship was MUCH better.
Seems logical, as the two wires, hot and neutral, were separated by quite a wide margin. At places where wire had to be suspended, real ceramic insulators were used. And where they went with the wire through holes in floors, ceilings or joists, etc., they put the wire through a protective tube.

I myself have always thought knob and tube was actually a GOOD wiring method. It's just that they had no ground wire.

What bothers me today about romex is that the hot and ground or neutral wire is very close to each other in the sheathing. I have seen where squirrels or mice have eaten the insulation off in the attic and bare copper wires are right next to each other! That would never be the case with knob and tube. Also I do not really care for the way the light fixture manufacturers today run both the hot and neutral wire through the same grommet hole, and I have seen the insualtion burn off where these wires are almost contacting each other! With the knob and tube, and the old light fixtures, you'd never see that problem.

And there are an awful lot of houses built in the 1800's, that have knob and tube to this day, and have never burned down.
 
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Old 11-13-07, 03:11 PM
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Originally Posted by Henry V View Post
, and at some point in its history, someone elected to change the lighting scheme in several rooms. As part of the process, they removed some lights and, presumably in order to keep the circuit alive for the retained lighting, spliced the wires and buried them in the walls.
Yes, this was common. I have run into this alot. And I have also reactivated those circuits by re-installing the light. It became 'dated' to have ceiling lights, so, some decades back, it became chick to not have ceiling lights in say the living room.
 
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