Knob and Tube Wiring (K&T)

 Knob and Tube wiring.  One of the greatest inventions in the history of mankind as this was the vehicle to deliver electricity to homes and businesses in electricity’s earliest days. The electrician installed the wire via porcelain “tubes” that the wires traveled through the joists through and then were attached to the joists via the “knobs”. The “hot” wire was on one joist and the “neutral” wire was nailed to the opposite joist.

What a fantastic treat for homeowners, that  previously had to light a candle to see, to flip a switch and have light from a lamp! Quick, easy and efficient. Knob and tube wiring first came out in the 1880’s and was used until sometime in the 1930’s. These systems are still being used in some homes to this day. “Back in the day” these systems were a homeowner’s dream. Today this system can be the things nightmares are made of.

The original purpose of knob and tube systems (K&T) was strictly for lighting. There had been no other appliance or electrical invention available for purchase at the time of it’s inception. This wiring is not practical in today’s electronic age. The system is only two wires which means it lacks a grounding conductor (the third wire designed to carry fault current to the panel to open breakers in event of a short circuit) and it lacks the capacity to carry the demands of today’s modern home. If you have knob and tube in your home there is a high probability that someone has worked on it over the years that wasn’t qualified. Adding load or improper connections on a K&T system can turn a benign system into a fire starting menace. Most Insurance Companies choose not insure a home with a certain percentage of it’s wiring system as K&T. Covering K&T Systems with insulation causes excessive heat to build up on the wiring and can cause fires quickly. NEVER PLUG A SPACE HEATER INTO A K&T SYSTEM as resistance elements play havoc on the terminations or connections, that were soldered or just twisted together and taped. K&T systems were great for their original intended purpose but if you have this wiring in your home it would probably be best to have it evaluated sooner than later!

If you are buying or selling your house in the Cincinnati Market there is a good chance your buyer will not be able to secure insurance coverage on a home with knob and tube wiring in it. Insurance companies were allowing the “cosmetic repair” of these systems. Meaning you could remove the visible knob and tube wiring from attics and basements. Great idea to mitigate the thermal dissipation issues of covering these systems with insulation. Bad idea for two reasons:

One: A lot of the people performing these repairs were Handyman and not electricians and the actual repair was causing more problems than leaving it alone. K&T wiring has to be landed to the standards of the NEC. It is not as simple as pushing the wire in a box and putting a wire nut on it. There are specific Codes that govern it’s installation into junction boxes, bonding of that box and securing it to the box. These Codes weren’t being followed. Inspections by the AHJ were not made on these repairs and now you have a plethora of systems with dozens of Junction boxes on them that are not correctly installed.

Two: You have now added romex wiring to the visible areas. That’s great. The biggest problem now is the stuff in the walls and connected to your outlets, tv’s, lights and appliances is still ungrounded rag wire. What does this mean? It means if you have a hot wire touching a metal plate, lighting fixture housing, or anything that is conductive  and you contact it, you are the path to ground and you could be electrocuted. People unknowingly may see romex in the basement and think the wiring in the walls is modern and then install grounded outlets to the old wiring.

As well as it being an Insurance issue, these were AWFUL suggestions for remediation that were put into motion by home inspection reports that listed “Knob and tube is dangerous under insulation, replace visible wiring”. These recommendations were followed by realtors and sellers and were even accepted by some Insurance carriers as acceptable. It is definitely the cheapest band aid available and many people utilized it because of the cost factor. Perfectly understandable, however it is not a proper remediation technique if the installer is truly concerned with the safety of the occupants and the livability of the property. We will not utilize a cosmetic approach to “mitigating” these dangers even if we could. The only way to mitigate the problems associated with Knob and Tube wiring is to update it.

Most Insurance companies have gotten away from insuring knob and tube wiring at all. Regardless of the attempts to “band aid” the issue. They catch these systems in the buying and selling process and make the seller or buyer update them in a specified amount of time or lose their coverage. It has become a hot button issue in the local market since it is so costly to properly mitigate these systems. Make sure you check with your insurance company when you are buying a house that has K&T wiring in it. Most won’t insure them any more.

Cullen Electric offers whole house, or partial house rewires to remedy these conditions. We have over 140 years of combined experience in working on your older home. We understand the challenges faced when dealing with plaster lathe walls, concrete filled first floor exterior walls, and everything in between. Whether you are buying or selling or just want a safer home…You can trust your large rewire project to Cullen Electric!