Replies

1. 
   4Lorn1 | Oct 31, 2002 09:15am | #1

   A moderate fire hazard when buried in insulation if maintained in good shape, K&T is designed to be directly air cooled and to not be dependant on insulation of each wire, it is a major hazard to anyone who goes into these spaces.

   The insulation on individual wires was usually rubber based. The industry realized that the rubber would deteriorate fairly rapidly in some spaces. When the insulation gets stiff and brittle enough it will fall off. K&T was designed to continue to operate without this insulation. It is isolated from the structure with ceramic knobs on nails and tubes where it goes through the woodwork. If left undisturbed it is relatively safe as long as it is not overstressed.

   When left out in the open, as intended, the potential lack of insulation on the wires is not a great problem. A tradesman crawling through the attic just has to avoid contact. Without the thermal insulation the wires are easily visible and, with care, simple to avoid. This serves two purposes. It keeps the worker safe from electrocution and keeps the K&T safe from the tradesmen. If the runs of K&T are crawled through, trod upon or otherwise molested they can loose all inherent safety built into the system.

   When thermal insulation is placed or blown in around K&T runs they are no longer visible. Without an extensive archeological dig their location is a mystery. Not knowing where they are it becomes quite easy for someone to accidentally touch an uninsulated wire and get a nasty shock or to catch a boot and yank loose connections without knowing it. The risk is in the manner of meeting new friends:

   1) The county coroner drops by to drag that 300 pound electrician out of your attic.

   2) The members of the local fire department come over and want to do mean things to your house with axes and hoses. 

2. 
   MajorWool | Oct 31, 2002 10:07am | #2

   See my post from a few days ago about a new tool for removing insulation. Part of this project is to locate the remaining K&T in the attic, and being able to suck up all the insulation around the wires is great since much less has to be removed to expose them, plus I can trace a wire across several joists without having to move which reduces the chances of a "punch-through." I also put this remaining K&T on an arc-fault breaker to give additional protection, well, it helps me sleep better at night until it is gone for good, which should be sometime Saturday afternoon.

   My experience with old wire so far is that it is best left alone unless you are prepared to do a major project. Also, never touch anything around 5:30PM on a Sunday. And that includes pulling down ceiling fixtures. I looked at a bathroom light in April, all the insulation crumpled, and I finished that project in June, all because I just wanted to replace the 8 ft of wire from the fixture to the switch, as it looked funky. This time I want to do all the exploring up front rather than one light, receptacle, switch at a time.

   Are you sure the walls are insulated? Mine sure aren't.

1. 
   Dogdazed | Nov 03, 2002 07:59pm | #3

   Wood,

   My experience with old wire so far is that it is best left alone unless you are prepared to do a major project.

   You said it all there.  I started a "room by room" re-wire in our old house, and ended up in the dark in no time flat!  It all went well, but when the whole house is wired with what seems to be no rhime or reason, it adds to the fun.

   If I was the homeowner in this post I would not start the rewire, although the buyer's home inspector may have a say about that. 

   J