Knob and tube wiring consists of a single strand copper, so for one circuit, two sets of wire had to be run. In addition to the ceramic insulators, this method of wiring was more expensive than the newer two strands of copper in a rubber sheath which only required one hole to be drilled per beam and needed no additional inserts for insulation. The mainboard for a knob and tube wiring system has fuses and hence is not ideal for today's modern high wattage appliances. Typically a home that has not been upgraded will only be a 40A or 60A service and can not support more than a light per room and a couple appliances. Because intersections in knob and tube wiring consist of wire fusions that are not separate from your house framing, this type of wiring is largely regarded as a fire concern by insurance companies.
Knob and tube wiring is easily identified by two prong plugs in homes that are over 80 years old. If you suspect you have knob and tube wiring give us a call to get a FREE estimate on upgrading your service.