Knob & tube & Insurance Co.?

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davidr43229 said:
The biggest problem with knob and tube wiring has nothing to do with the
original wiring. It has everything to do with what has happened after the fact.
Most old houses do not have as many electrical circuits as new houses. If a
circuit became overtaxed and 15 amp fuses were constantly blowing, some
illinformed home owners would put in 25 or 30 amp fuses to ?solve? the
problem. Allowing 25 or 30 amps to flow through a wire which was not
intended to handle that much electricity, causes the wire to overheat.
This can cause the wire and the insulation to become brittle.
Some would argue that knob and tube wiring does not have a ground conductor. I would remind them that even modern wiring installed between 1950 and 1960 does not have a ground conductor.
Just my $.02
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I agree in most cases the K&T is safe. But is is the select few that scare every one. The Two most common situations I see that cause problems are the loom that protects the wire going into the box has slid away and it leaves the hot and neutral wires rubbing on the metal box, causing a short. Second is rodents, The seem to like to chew it, and die across the conductors, causing a short.
 
I have not found a type of insulation rodents won't eat. Geerators are a favorite haunt of vermin, warmth and a food source.
 
OK. Time for a magnetic field comment. The separation of the conductors causes a huge magnetic field, even with a single light bulb on the circuit. Though still considered "controversial" the connection between magnetic fields of just 4 milligauss and childhood leukemia has now been accepted by a very conservative World Health Organization.

So if there are going to be children in the house, use your sense of ..... ? what to call it? Honor, integrity, caution? Are the owners aware of the issue?I just wouldn't keep it except in areas not usually inhabited.

Karl
 
karl riley said:
OK. Time for a magnetic field comment. The separation of the conductors causes a huge magnetic field, even with a single light bulb on the circuit. Though still considered "controversial" the connection between magnetic fields of just 4 milligauss and childhood leukemia has now been accepted by a very conservative World Health Organization.

So if there are going to be children in the house, use your sense of ..... ? what to call it? Honor, integrity, caution? Are the owners aware of the issue?I just wouldn't keep it except in areas not usually inhabited.

Karl
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What about 3-ways in 12-3 or 14-3 NM cable?
 
K&t

K&t

acruc10, thanks for the idea. I didn't think of putting in a clamp. Not thinking out of the box as they say. :) Tomorrow I am going and put them in before the inspector gets there.
 
guschash said:
acrwc10, thanks for the idea. I didn't think of putting in a clamp. Not thinking out of the box as they say. :) Tomorrow I am going and put them in before the inspector gets there.
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It was very easy to do. I discussed this with the building inspector and all he wanted to see was a ground connection. "IMO'' it is a much safer installation being that it limits the movement of the NM "in the box" I would just becarful not to over tighten a clamp.
 
arcrw, are you asking about magnetic fields from 3-way circuits? If so, no fields if wired with 3-conductor travelers.

Karl
 
karl riley said:
acrwc, are you asking about magnetic fields from 3-way circuits? If so, no fields if wired with 3-conductor travelers.

Karl
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That is what I thought to be the case. I know 2-wire travellers can be a problem. we just rewired a condo and all the old 3-way switchs were run in 2 wire. Just how far away from the conductor ( 120volt 15amp) does the EMF radiate out in this type of system?
 
Magnetic field strength from a single conductor, as in the case of using 2-conductor travelers, weakens diretly with distance, which is a slow rate. The formula is magnetic field strength in milligauss (B) = 2 X amps divided by meters. B = 2i/m. So a 2 amp current would give 4 mG at 1 meter out.

Easy to calculate if you know the amperage. 4 mG is the level conservatively known to be associated with the doubling of childhood leukemia. Since kids are close to the floor, a circuit running under the ceiling could give a higher field. 1 foot away would be 13 mG.

Net current is the same as a single conductor. 4 amps of hot and 2 amps of neutral is the same as 2 amps on a single conductor.

Karl
 
jeff43222 said:
It does, but most rodents are illiterate, and the few that can read are usually stupid and like to show the others how tough they are. :D
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You guys have it wrong -- "NM" stands for "Non-Munchproof", "MC" stands for "Munchproof Cable" and "AC" stands for "Almost Munchproof".

Got rodents? Get a cat.
 
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