What is Knob and Tube wiring?
Knob and tube wiring was the go-to wiring method for buildings from the 1880s through to the 1940s. Tens of thousands of homes throughout Massachusetts, Connecticut and Rhode Island have this type of wiring. If your home was built during this time chances are it has or once had knob and tube wiring. The best place to search for the presence of this type wiring is the basement and attic. In the basement look between floor joists and at sills along the top of the foundation. In the attic search between ceiling joist and rafters. If the attic is insulated (not uncommon because the dangers of knob and tube were not known twenty years ago) lift the insulation in different spots and look beneath. If you see white ceramic knobs and porcelain tubes along and through framing members strung with two runs of wire running parallel this is knob and tube wiring. The wires were meant to stay apart from each other and in the open allowing air to circulate to prevent overheating.
Issues Associated with Knob and Tube Wiring
One of the biggest issues from our perspective is the genuine concern that insulation that is in contact with or covers up this outdated wiring can cause overheating and lead to fires. This is the main reason why so many older homes, even with today’s high energy costs, have very little insulation or none at all. Think of the energy lost in these old homes. In fact this issue is so wide spread that MassSave and EnergyWise sponsored by the utility companies in your area both offer zero interest loans up to ten thousand dollars to remove this potentially dangerous wiring allowing for new energy saving insulation to be installed.
Another common trait with this wiring are two slot outlets which do not provide for a ground. Even if the old two slot outlets are replaced with newer three prong outlets there is still no third wire (thus no ground) to prevent shocks.
Other common problems stem from amateur modifications done incorrectly. Always hire a licensed electrician when working with old wiring.
Lastly, knob and tube wiring does not have the electrical capacity that modern families require. Today’s appliances and electronics and all the other plugged in things in our home demand much higher electrical loads than the wiring was originally designed for.