bob haller wrote:
how many links do you want posted?

heres one, i can flood the board if you like.

sadly bud is living in dreamland, where stuff thats 100 years old is
just fine

My "dreamland" is based on years of experience as an electrician. Much
of it was doing service calls where I saw numerous K&T installations.

I believe Roy, another electrician, has also written K&T that has not
been abused is not a problem.

halerb had a nightmare where he was attacked by knobs and was forced to
hide in tubes.


To look at claims of K&T hazards:

Oversized fuses allow much more current to flow than originally
intended, resulting in additional heat in the conductors. This heat
causes the insulation protecting the wire to become brittle, and
eventually to disintegrate.

Over fusing is a problem for any wiring method. One could argue that K&T
is more immune in that wires are not in contact with each other until
they reach a box.

Heat directly above ceiling lights and in un-vented attics can also
degrade the wire insulation.

I have seen no evidence of problems in attic wiring. I have salvaged
wire out of attics that was in like-new shape.

Heat at ceiling lights can certainly rot out insulation. It rots out
*all* insulation including plastic. I have seen rubber insulation on BX
and plastic insulation on Romex crack off when the wires were moved.
Light fixtures now have ratings for the temperature rating of the supply
wiring. And Romex now has a higher temperature rating. What about the
old 2 wire Romex? If anything K&T is safer because the wires are not in
contact until they reach the box. It is not easy to fix BX where there
are bare wires back to the connector.

Some types of insulation used on knob and
tube wiring seem to be a delicacy for the critters that find their way
into old homes. They can make short work of the insulation covering
the wires.

"Critters" can be a problem for Romex.

None of these problems are unique K&T hazards.

Faced with drafty houses and high heating bills, homeowners often add
thermal insulation to their attics and walls. Insulation on top of
knob and tube wiring is a major fire hazard.

As posted previously
http://www.waptac.org/sp.asp?id=7190
is a report to the Illinois Department of Commerce and Community Affairs
on adding building insulation around existing K&T wiring. The report
looked at available information on hazards of insulation around K&T. The
report found no record of hazard was found in the large number of K&T
installations that had insulation added around them. Larry Seekon, whose
comments are quoted, was head electrical inspector in Minneapolis.

There is no reason to believe "insulation on top of knob and tube wiring
is a major fire hazard". This is home inspector FUD. Where is the
supporting data.

--
bud--