|Knob and Tube Wiring - an unbiased
By Bill, KNT Electric May 19, 2012
You've all heard it before "don't buy a
house with knob and tube wiring, you'll regret it, knob and tube wiring
is a fire hazard, knob and tube wiring is dangerous, knob and tube
wiring must be removed or else...". Are they right? The answer is maybe
and maybe not.
Fact, since 1980, there has not been a
single house fire that resulted in any loss of life or significant
property damage caused by knob and tube wiring. There has not been one
reported case. This fact should speak volumes on itself.
Knob and tube wiring was used end of the
1800s all the way up to the 1950's. That is over 60 years of proof that
knob and tube wiring works. In ways it's actually better than the new
wiring methods we use today, but don't the home inspectors won't tell
you that would they?
#1 - Heavier gauge copper wire
Knob and tube wiring uses a heavier gauge
copper wire that are separated. I'm sure you know, in the past people
actually built things better and used higher quality materials. The
heavier gauge copper and individual wires allow more electrical
throughput with less resistance which means less heat.
#2 - Taped connections
Knob and tube wiring uses taped
connections after being spliced and soldered. If done correctly this is
a very safe and stable method of connecting electrical wires. I've seen
homes built in the 1940s who's knob and tube wiring is still functioning
well even after 70 years?! If this isn't good craftsmanship, then I
seriously don't know what is.
#3 - Codes still recognize it
Modern building codes still recognize
knob and tube wiring as a safe and stable method of wiring a home. Even
without the presence of a ground wire. In most applications around the
home, a grounding wire is not necessary.
#1 - Abused and damaged knob and tube
Knob and tube wiring that has not been
disturbed is usually safe and stable, HOWEVER, this is usually not the
case in the vast majority of homes today. People move, people neglect,
people upgrade, and rodents like to chew. These are the most common
reasons why knob and tube wiring degrade over time and time is certainly
a major factor here. As I've mentioned before rubber has a useful life
of 25-30 years before it begins to brittle and lose it's elasticity.
Abused and damaged knob and tube wiring is a safety hazard and has
potential to start a house fire.
#2 - Over-fusing
Over-fusing essential means connecting
too many electrical appliances to a given connection. This results in
heat, flickering, blown fuses, smoking, sparks, and potentially a fire.
Knob and tube wired homes are dated, they simply were not designed to
power modern appliances and households that now include fully furnished
basements. The long term consequences of over-fusing are, brittle wires,
damage to insulation. This degrades knob and tube wiring very quickly.
Although undisturbed knob and tube wired
homes may appear to be safe and working, I strong recommend homeowners
hire a licensed electrician to inspect the system. It's an outdated
method of wiring a home and despite the advantages of it, knob and tube
wiring has been abandoned by the industry for over 60 years. The service
life of existing installations have far-exceed it's useful life and I
can only recommend the replacement of this good but antiquated system.
Disclosure: the author
of this article is a Master Electrician with KNT Electric. If you have
any questions or concerns please call Bill at 647-880-0881 anytime, or
if you prefer to use email, please email "firstname.lastname@example.org"
An image of splicing knob and tube wiring
with another wire. Very dangerous, but common by homeowner's who like
DIY "crafty" solutions to save a few dollars.