What is Knob and Tube Wiring?

When it comes to electrical wiring in homes, safety should be number one priority. Knob and tube, known to be found in homes built before 1930’s, pose risks due to outdated practices. Knob and Tube wiring consists of individual copper conductors covered in cloth insulation running through porcelain insulated tubes supported by ceramic knobs. 

Today, it does not meet modern electrical standards because of knob and tube’s lack of grounding, insulation degradation and inadequate load capacity. Knob and tube wiring was built to withstand the electrical use of its time. As technology has advanced and made leaps and bounds, it is unable to power the technology of today as safely or efficiently of 70 or more years ago. The knob and tube wiring are also known to degrade and leave wires exposed thus leaving your home especially vulnerable. 

While the National Electric Code (NEC) does not prohibit knob and tube wiring, it still requires that all electrical systems meet current codes standards and requirements. The following codes are relevant for homes in Washington state. 

  1. NEC 210.4(D) This section requires that all habitable rooms have at least one receptacle outlet installed on each wall, within specific distances from the wall edges. Knob and Tube wiring may not be able to accommodate this requirement without modifications. 
  2. NEC 300.3(A) This section requires wiring methods must be installed in a manner that does not damage the insulations or integrity of conductors. The fragile nature of knob and tube wiring makes it very difficult to adhere to this code. 

Many homeowners are unaware of the state of their homes electrical wiring. It’s important to stay informed and get your home inspected, ESPECIALLY if it was built before the 1940’s or 1950’s. Our team of licensed electricians are experts in home electrical wiring and will make sure your home is safe for all that live in it. 

Give our team a call to schedule a yearly inspection to make sure that your home is safe and stays safe year in and year out. Mention the knob and tube wiring to a service advisor today.

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