Knob and Tube Wiring

The argument over safety aspects of knob and tube wiring will continue for many years.

Is knob and tube wiring safe?  As with many things if the knob and tube wiring in your home has been properly maintained there should be no concerns with respect to fire.

However, even the finest knob and tube wiring installation has one major drawback and that is that there is no ground wire, making the use of GFCI style receptacles and GFCI and AFCI breakers useless, hence with knob and tube wiring there is a greater chance of electrical accidents within the home.

Knob and tube wiring has not been used in homes since the 1950's and the question that must be asked, is how has it been maintained and upgraded.  As most homes in the 1950's had 30 or 60 amp services, which are hardly adequate for today's home electrical needs.

The problems with knob and tube wiring are associated with the age of the electrical system, its maintenance and how upgrades and changes have been accomplished.

Insulating walls and attics in conjunction with knob and tube wiring can be a problem.  The National Electrical Code is very specific about NOT burying knob and tube wiring under insulation and although some US jurisdictions, such as California, have over-ridden this code, those that have, have specifically stated that the knob and tube wiring has to be inspected by a licensed contractor prior to the installation of the insulation.

Insurance companies, throughout North America, are beginning to take the approach that they will not insure or reinsure homes with knob and tube wiring, in a similar manner of not insuring homes with fuse panels.

Following are a group of pictures that involve knob and tube wiring. 

Click on pictures for larger view.

Knob and tube electrical fire.	Fire between ceiling and floor was only identified when ceiling was removed for renovation.  It is assumed that the fire did not spread because of lack of oxygen
Incorrect connections of new wiring spliced to knob and tube wiring.
Knob and tube electrical panel buried behind a cupboard door.		Splice between 2 knob and tube insulators has overheated and scorched floor joist
Over the years, modifications and repairs to knob and tube wiring.

Yes, you should have your home's electrical system inspected by a qualified electrician if you have knob and tube wiring.  However, that being said, many problems with knob and tube wiring are buried behind walls and in ceilings.  Personally, I would undergo the expense of re-wiring the house in order to sleep soundly at night!