Replacing Knob and Tube Wiring

What is Knob and Tube Wiring? 

Knob and Tube is antique wiring that was first installed in homes in the 1880’s and used until the early 1930’s. Starting in 1903, electricians had the choice to use either knob and tube wiring or BX wiring (armored cable). The interesting fact is that electricians continued to use knob and tube wiring instead of BX cable because it was a cheaper material. The BX wiring was without a doubt easier to install, but at the time, electrical labor was cheap and electricians opted for the cheaper K+T wiring.


What to expect from the replacement process

The first step in the process is to get an estimate from a licensed electrician.

The electrician will need to fish wiring throughout your home to replace all the old wiring. This can be done without taking walls down and without having to run surface conduits all over your house! I can’t stress this enough. We hear from many homeowners –“Wow, the last electrician said some walls would need to be ripped down and run pipe in some spots!” It’s 100% possible to fish wiring throughout your home unless you live in some kind of cement home (my one disclaimer!).

Wallpaper can pose some issues  when we need to make holes to fish the new wiring. Depending on the condition of the wallpaper, it can often be sliced, peeled away from the wall, then glued back. If the wallpaper won’t peel, it then typically rips.

Does My Home Have Knob and Tube Wiring? 

Easy signs to identify knob and tube wiring are porcelain knobs and tubes in the unfinished basement and attic. If the knobs have a black/brown wire on them, call a licensed electrician to test the wiring and see if it’s live.

Will I be without power while my knob and tube wiring is being replaced?

Fortunately, the answer is no. The electrician you hire should be able to maintain most, if not all, of the power throughout your house during the process. To make this happen, the knob and tube wiring will be capped off as the electrician begins rewiring the home.

Let’s say one particular knob and tube circuit has six outlets, four lights, and four switches on it. On the electrician’s first day, he may only be able to rewire half of those items. The other half may be important for you to have on during the night. By capping the knob and tube wiring off, that circuit can be turned back on so all the power is on as it was before the electrician started. There are a few cases, especially with staircases that use three-way switches and four-way switches. Once the wiring is started, it will need to be finished before powering back up. In this case, you may need to go a night without those lights on. This is mainly due to the extreme difficulty in wiring these switches.

Pro Tip

A main issue is with staircases as they can take a LONG time to wire. Some homes may have 3 flights of stairs, with all the switches and lights working together. In these instances, it may take more than an 8 hour day to run all the wires and install the boxes. Getting those lights back on at the end of the day may not be possible. If the electrician you are hiring is telling you ALL the current knob and tube wiring will need to be off through out the entire job, look elsewhere!

Want More Information?

A digital version of the Knob and Tube Wiring Guide is available for purchase on Amazon.

A digital book that will take you through the entire knob and tube re-wiring process.