Knob and tube question

[Leanne]

We just bought a house and the inspector told us we needed to replace 2 knob and tubes. They were the ones visibly leading into the Main panel and were found to be connected to 2 outlets in the house. We bought the house feeling confident that this was a minor repair.

Today we had an electrician in to give us an estimate. He traced all the knob and tube to transfer boxes - romex cable then led to the Main Panel. This house was updated to 100amp in the 70's, and so they only replaced the knob and tube coming directly from the main panel. He insists we have to completely rewire the house (5000$!!) We are thinking that we just hire someone to replace the 2 knob and tube cables that come directly from the Main panel (500$). Trouble is our insurance depends on this replacement. Will they insure us if we take the 500$ route?

ps our basement is unfinished and shows all the knob and tube -

[kactuskid]

Knob and tube wiring is usually fine as long as the insulation on the wires hasn't deteriorated and started to fall off. Course none of us here can see the installation to know if it's safe or not. The splices need to be installed properly and K &T is not allowed to be covered with insulation. Here's a link that'll tell you a bit more about older wiring.
http://www.oldhouseweb.com/stories/Detailed/10327.shtml

You'll need to ask your insurance company what their requirements are, no way for anyone to know the answer besides them.

And I would suggest getting a couple more estimates for the job to see what other electricians suggest, try to hire companies that are familiar with older wiring.

[HayZee518]

There's nothing wrong with knob and tube wiring unless the insulation has deteriorated and the splices are intact. What they did in the olden days is run a large size wire the length of the house and tap off this "main" to the branch circuits with fuse boxes at each branch circuit breakout. The splices were twisted together and soldered then taped. Over time the splices would weaken and come apart causing faults and heat. This would lead to a fire.
Also what you'd find at the older installations is at the fuse blocks (porcelain blocks) would be over fusing - i.e. 30 amp screw type fuses on a 14 gauge line - a hazardous condition. I've personally re-wired 8 houses in Massachusetts with knob and tube and what I found would make any house inspector cringe! Mice seemed to like the jute fiber insulation and I found many runs bare for about a two foot run.

[jtfoxman]

I have spoken with a few electricians in my area regarding this since I have some in my attic and they say the knob and tube is actually very safe. As long as the insulation is in good condition.

[Snoonyb]

K&t

When you replace it, save a couple of the tubes, they are good knife sharpeners.

[Phelps]

I've personally re-wired 8 houses in Massachusetts with knob and tube and what I found would make any house inspector cringe! Mice seemed to like the jute fiber insulation and I found many runs bare for about a two foot run.

Mice and K & T, or squirrels and Romex. Pick your poison. I choose the K & T. Why? This Romex wired house I saw, while up in the attic would REALLY make you cringe.....or an inspector to condemn the house. I saw bare eaten wire exiting one attic area, up over rough-sawn fibery wood, where all the insulation was eaten off the wires! ALL of them! And because Romex is Romex...these wires were within about 1/16 inch of making contact with each other and shorting out.

I told the landlord who was an ex-electricians helper and he went up there and doctored up every wire somehow, he said.

[Phelps]

I have spoken with a few electricians in my area regarding this since I have some in my attic and they say the knob and tube is actually very safe. As long as the insulation is in good condition.

That is because the hot and neutral wires are spread apart, and go around ceramic insulators and when passed thru cavities, are placed inside protective 'tubes'.

Btu HayZee mentioned about deterioration of the splices (I think they call these "flying taps", or something like that)...and that is a point well made. But I wonder just what it was catching fire on up there.

[HayZee518]

The old house used newspapers for insulation. Unlike cellulose which is treated with a fire retardant, regular ol newspaper paper is very flammable when old and dried out. One house I owned had newpaper plate blanks in the attic under the floors. Paper much like compressed paper mache with impressions like that of a newpaper column ready for printing.

[Phelps]

Ya. That wouldn't be good then.