What the heck is Knob and Tube wiring?

The short answer is it is something that you do NOT want in the home you are buying, or any home.

Knob and Tube was the first kind of electrical that was used from about 1880 to 1930-ish.  It looks like this…


The Knobs hold the wires in place and the tubes protect the wires when they go through joists and wall cavities.   There are only 2 wires, a hot and a neutral, no grounding and they are both covered in a cloth sheathing so it is hard to tell which is which.  A non contact voltage tester is the best way to tell if this wiring is still in use or not.  Sometimes the wiring is cut and not in use but the wires are left in place.  Sometimes it is still in use.

If you are purchasing a home and there is LIVE knob and tube you want to get an electrician out to take it out and replace it right away.  Knob and tube is no longer the electrical standard and poses a fire risk.  Especially when it is buried in old cellulose insulation up in the attic or behind the walls.  Not only is this a safety issue but it can be a homeowners insurance issue.  If you own a home with knob and tube and a fire is caused by it, you may not be covered.

The best places to spot knob and tube wiring is in the basement (look up) and in the attic (look up and down).  Also these old light switches are commonly wired with Knob and Tube…

Gently take the cover plate off, NOT the switches!  Look on the side for the cloth wiring.  If you see cloth wiring call an electrician.

Knob and Tube wiring should be removed in all homes.  Make sure to share this with anyone you know that has this type of wiring in their home still.  If you’re not sure snap a picture and send it over to your electrician, or send it to us here at Knox Home Inspections and we can help you out.

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Typically when buying a home people are always worried about service size for their electrical systems?  Do we have 100 amp or 200 amp?  That is how much power is coming into your home and how much your main panel can safely handle.

One thing that people don’t often think about is WHAT BRAND is my main panel?  There are a bunch of different kinds…. Cutler Hammer, Crouse Hinds, Square D, General Electric, ITE, Siemens, etc.  Then there is FEDERAL PACIFIC.

Federal Pacific was a company that started in 1950 and was very popular all the way up to 1988 in some areas, including America and Canada.  Over time these panels had a higher failure rate than other panels.  Studies were performed and it was found that these panels had several different problems.  Mainly with the inability to trip the breaker off when necessary.  Other breakers will shut off and stop the flow of power and prevent a fire.  The failure rate on other brands of breakers is much much less than a Federal Pacific breaker.

It is estimated that Federal Pacific Panels are responsible for 2000 fires ANNUALLY.

Luckily an FPE panel is very easy to identify.

  1. Look for the bright RED tabs on the breaker fronts.  No other brand uses this style of breaker size indicator.  Think red = danger / red = STOP
  2. There may be a sticker with the company name still on it, either inside the panel cover or near the top.
  3. The breakers are BACKWARDS!!!!!  On any other panel the breakers are pointing towards the center when they are switched ON and they are pointing to the outside when they are OFF.  FPE breakers are opposite and it makes the cover difficult to remove.

When shopping for a new home make sure to look at the BRAND of panel that you are buying and discuss it with your Home Inspector.  If you see the warning signs above you should plan on a full panel replacement.  May as well call an electrician for a quote right away and save time, your home inspector will recommend a replacement anyways.

If you know anyone with one of these panels in there home, please, urge them to replace it.  Or at least call an electrician to tell them more about the danger.

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