Guitarhacker
In addition, during certain times in the past, some electricians thought it was a good idea to wire houses with aluminum romex. It was cheaper than copper, and copper was in short suppply at the time and very expensive.....It was permitted by code at the time, and some of this wiring still exists in homes today. I would not sleep in a house wired with this stuff. It would have to come out and copper installed.

I lived in such a house, and I had no idea how dangerous the aluminum was until I read about it after discovering the "peculiar silver wiring" when changing out an outlet.  Can you believe we paid for a home inspection and it was never reported to us?  Like 500 bucks for nothing.  And we had no recourse.  I don't remember the details now but it was decided we were screwed.
 
I did pull all new copper in the whole freakin' house.  It was miserable.  I learned alot..but I did not enjoy it. 
 
Oh, and what's the deal with aluminum 220?  We're renting a house now with all copper wiring, but the 220 run to our electric stove is aluminum.  Why on earth would that be ok?  Seems like that would counter code or something. 

I would be far less concerned with shock than I would be fire. Having done a lot of electrical work myself in older buildings, the things I have found have scared the bejesus out of me. Sometimes trying to convince the owner to replace the wiring is impossible, and I found it distressing to walk away from a house or building knowing that the old wiring was a disaster waiting to happen.

Around here, a lot of the old walls are not slat and plaster, but wire and plaster. Difficult and dangerous to open up. I suspect todays houses are a whole lot lighter than the old ones as those wire/plaster walls were heavy.

However doing renos on old houses can be, as stated, quite fun. I have found things lots of odd things in walls we opened up.

you guys are very helpful, I live in Lodi, California. The houses are going pretty quickly here. bidding wars.  the house looks like its from the 1920's or older but the date says unknown on the records. The home inspector said the foundation seems to be standing nicely, the faucets and toilet work. The gas was off  and the thermostat was missing so we are asking the seller to turn on the gas and check the heater, make repairs if neccesary. This loan is fha  so we are asking the seller to make all health and safety repairs.

Oh, and what's the deal with aluminum 220?  We're renting a house now with all copper wiring, but the 220 run to our electric stove is aluminum.  Why on earth would that be ok?  Seems like that would counter code or something.


No actually..... most wire bigger than #6 tends to be run in AL rather than CU...again for cost.

The big problem with the AL wire to outlets is that there is two dis-similar metals in contact with each other.... that causes problems. And also the 12 guage aluminum will break easily after a few twists....and aluminum is a much softer metal so it "oozes" under pressure and the result is the connection becomes loose over time. A loose connection causes heating.... and heating causes...fire. 

However, on a stove feeder, or even the main service feeders into your panel, the aluminum there is OK because:
1. it is connected to a lug that is approved for aluminum contact
2. a chemical "de-ox" compound is supposed to be used to **** oxidation
3. these wires are large enough to be torqued down properly so loose connection are generally not an issue.


Bit: the key word there is "theoritical".  I have also seen people put stuff...like cake pans and such in attics, and the pan slides off what it was setting on and shorts the K&T conductors..... where the squirrels have eaten the insulation off..... I was called to check a "fuse that blows every time we put a new fuse in it" and yeah... it was a 15 amp circuit with a 30 amp edison base fuse screwed in......

I used to hate servicing the K&T wiring..... due to the "leaks" in the circuits and the switches that were used..... (the dual push buttons)..... those suckers never seemed to cut off the current totally like today's modern switches do.

What's "knob and tube" ?

ok, another question, If Iplug a cyberpower surger protector into a outlet that has knob and tube wiring, would it protect the computer from surges and whatnot? This protector says it has a built in on off switch with 15amp circuit breaker. could I use this for the computer outlet or tv outlet? maybe for the  music room outlet to plug in my guitar amp. just curious if I had like 5 of these surge protectors if it would protect for now til I would get the electricity replaced. we are still in the deciding phase still if we r going to further buying the house. we are out $400 so far for the home inspection.

The big problem with the AL wire to outlets is that there is two dis-similar metals in contact with each other.... that causes problems. And also the 12 guage aluminum will break easily after a few twists....and aluminum is a much softer metal so it "oozes" under pressure and the result is the connection becomes loose over time. A loose connection causes heating.... and heating causes...fire.

   A connection becoming loose isn't just common to aluminum.
What you say is true but may I add that workmanship is a
factor? I've seen connections "fail" everywhere from plugs on
up to even the power companies connections outside the
house. (be it aluminum or copper).

   There are so many other things as well that can cause
a connection to "fail" even if the workmanship is good in
the (say a wall plug). The wire in some of those "molded"
male plugs on such things as space heaters and window
a'c units and other things like a vacuum cleaner over time
start "burning into". As they do they heat up and make
the (wall plug) become warm and then onto hot.

  Many connection "failures" could have been caught
before the damage is done by simply knowing the
connection is "running hot". Many people that I have
spoke with (home owners) don't even consider a
connection running hot as a concern. I've had many
customers say to me for example something like:

  You know? when I turn on my light switch or remove
a plug from the wall it sure is hot! I say "Don't that
concern you?" most of the time the answer is something
like "it's no big deal!"

   I've even had people look at me like i was "shooting
them a line" when I say a hot wall plug is dangerous.
Oh my gosh don't get me started now! Here is another
one:

  I get a call. the customer says they're kitchen light
doesn't work. I take the glob off and there are these
100 watt (or more) light bulbs. Sometimes 3. I say
that much heat is dangerous and these fixtures
are not "rated for that much wattage". They say
Oh! "but I need the light" "its too dark in here!

   What happened? It not only burnt up the fixture
but also the wiring inside the box in the ceiling.
There are those people who do show a great
deal of "concern" over what heat does once they
know about the subject. I just think that it's sad
that those who think (or give me the impression)
that it's "no big deal" think that way.



  

What is Knob & Tube.......?  LOOK HERE


If you used a UPS surge suppressor, that would be better than nothing.... however, those surge suppressors rely on a solid ground connection (which K&T doesn't have) in order to work properly.



Jimmy... you are so right about that.  I also have seen copper and aluminum connections get loose, oxidize, and burn up. Heat will do damage to the insulation in the J-box behind the light fixture...makes it brittle. More times than I can count I have gone into a box to fix something and had the insulation fall off from that very cause........

Knob & Tube

 
I was wondering the same thing when I started reading this thread the other day.
Lo and behold, on This Old House today they're building an addition to a house which has K&T, and the electrician says it all has to go. Another 5-6 grand out of the budget.

will the electrition have to remove all the knob and tube wiring and then install new wiring or will they just disconnect the electricty flow to these wires, leave them and add new wires. what is the new style wiring called?