Knob-and-Tube Wiring and Home Owner's Insurance
See the bottom of this page for late-breaking news.
In the last few, a number of our clients have discovered that they can't obtain insurance for the house they are about to buy, because it has knob and tube wiring or a 60 amp service. No insurance--no mortgage. No mortgage--no real estate transaction. Needless to say, we have had a number of concerned home buyers and realtors calling us to find out why we said the house was OK and yet the insurance company says it's not.
It appears that a significant number of insurance companies now consider knob and tube wiring and/or a 60 amp service unsafe or a significantly higher risk. We disagree.
Knob and Tube
It requires two wires (normally a black one and a white one) to create a circuit. With modern wiring, these two wires (along with a ground wire) are bundled together in a single plastic sheathing. Older knob and tube wiring was installed so that the black wire and the white wire ran separately. It was installed in houses up until about 1950.
Modern wiring runs directly through holes in the structural components (such as floor joists). Older knob and tube wiring used protective ceramic tubes placed in the holes to prevent the wire from chafing against the woodwork.
Modern wiring uses staples to hold the wiring against structural members when the wire is running parallel to the member. Knob and tube wiring used more elaborate ceramic knobs to clamp the wire to the structural member.
Connections between modern wires are completed within enclosed electrical junction boxes. Older knob and tube wiring had visible connections. The wires were spliced and soldered together and then wrapped with electrical tape. Ceramic knobs were used to secure the wires so that anyone inadvertently tugging on the wire would not be tugging on the electrical connection. These connections are commonly called "pig tail" connections because one wire is wrapped several times around the other wire before the two are soldered together.
Modern wiring is typically #14 gauge copper wire and capable of handling 15 amps. Knob and tube wiring is typically #12 gauge copper wire and can handle 20 amps. Often, older knob and tube wiring was dipped in solder prior to being wrapped with insulation and consequently, some of it has a silver appearance when the insulation is removed. This should not be mistaken for aluminum wiring. Note: Even though most knob and tube wiring is capable of handling 20 amps, we suggest that it be protected by 15 amp fuses because, in all likelihood, some modern 14 gauge wire may be connected to the older 12 gauge wiring.
From the above description, it becomes pretty obvious that knob and tube wiring is not dangerous. Knob and tube wiring which was installed properly, and has not been abused, can provide many more years of service. The biggest problem with knob and tube wiring has nothing to do with the original wiring. It has everything to do with what has happened after the fact.
Most old houses do not have as many electrical outlets as new houses. Most old houses do not have as many electrical circuits as new houses. If a circuit became overtaxed and 15 amp fuses were constantly blowing, some illinformed home owners would put in 25 or 30 amp fuses to "solve" the problem. Allowing 25 or 30 amps to flow through a wire which was not intended to handle that much electricity causes the wire to overheat. This can cause the wire and the insulation to become brittle.
Some home owners also decided to add additional outlets in the house and tie the new outlets into the old wiring. Instead of making proper pig tail connections which are soldered and appropriately protected, many home owners did their own sub-standard work. They would get out the pliers and a paring knife and whittle away at the wires until a connection was made. Instead of wrapping the connection with proper electrical tape, they used hockey tape, masking tape, scotch tape or even band-aids.
It is wiring that has been abused that is potentially dangerous. Knob and tube wiring, on its own, is not inherently a problem.
Some would argue that knob and tube wiring does not have a ground conductor. We would remind them that even modern wiring installed between 1950 and 1960 does not have a ground conductor. A ground conductor is necessary if you are plugging in appliances that have a 3-prong plug. If however, the knob and tube wiring is restricted to bedrooms, living room, dining room, et cetera, this creates no special hazard. Plugging a two prong lamp, TV, or clock into an old two prong outlet is just as safe as plugging them into a grounded outlet.
We feel that the insurance companies' rejection of knob and tube wiring is a knee jerk reaction reminiscent of the immediate reactions to UFFI and aluminium wiring.
We are hoping that the insurance industry will realize that this is not a black and white issue (no pun intended) and that the mere presence of knob and tube wiring does not, in itself, create a hazard. We feel the same way about 60 amp services, but that's another story.
Late-breaking news: At last, some relief for home buyers! Carson Dunlop has made arrangements with an insurance company who will insure homes with knob-and-tube wiring if the home is inspected by Carson Dunlop. Yet another reason to use Carson Dunlop when you are buying your next home!
View a related article from Canadian InsurancE-News.
Randy Yetman,
FRI, MVA
