How to identify a fixture/outlet and wiring to breaker as knob and tube

knob-and-tube

I have spent time charting out all the lights, outlets, etc. in our house and what breaker they are each on.

I know that most of the original part of our house in knob and tube and the early 90's addition is romex. Looking at my list I can see that a few breakers are most likely mixed, part K&T and part romex.

I believe each fixture/outlet could be:

  • Knob and tube from the outlet all the way back to the breaker box.
  • Knob and tube at the outlet, but changing to romex somewhere before the breaker.
  • Romex from the outlet all the way back to the breaker box.
  • Romex at the outlet, but changing to knob and tube somewhere before the breaker.

I could take off the outlet covers/lights to determine the first part visaully though that will be time consuming. Could I also use an outlet tester to determine if there a ground, with no ground meaning K&T at some point and a ground meaning Romex the whole way back to the breaker? Then do for each on the breaker to figure out what part is first/second?

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Best Answer

K&T could be at any point in the run, the circuit could start romex, then switch over to K&T and then switch back over to romex (potentially with a ground pulled from another circuit).

The only way to be completely sure no K&T wiring is in use is to find and trace all of the circuits and visually make sure.

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