We have bought a new house with knob and tube wiring. We are now looking into replacing all of it with new wiring and understand that significant wall-surgery will be required to run the conduits.

Question: Is it possible to limit cutting of the walls by running horizontal conduits above the ceiling or under the house? Doing it this way, could only short vertical conduits need to be run in the walls?

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    Most locations in most 1- and 2-storey houses can be wired fairly easily from either the basement or the attic; horizontal connections elsewhere are rarely needed. – keshlam Oct 18 '15 at 6:30
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    The difficult locations tend to be light fixtures on the 1st story ceiling in a 2-story house (or 1&2 of a 3-story, etc...) – Ecnerwal Oct 18 '15 at 14:05
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    Agree with the above 2 comments, but here's the deal: you will have to do a bunch of wall repair. While (a bunch of wall repair * 2) sounds like twice as much work, it's really more like (a bunch of wall repair * 1.2). So, save time drilling and getting around blocking by being generous with the holes you cut. Also, big-ish holes are just as easy to repair as small holes. – Aloysius Defenestrate Oct 18 '15 at 15:19

Like Aloysius Defenestrate said most wall outlets will involve little or no damage. Redoing the lights & back to their switches will be the still quite minimal anyway damage.

Additionally, if you're also considering re-siding the house or replacing floors this can greatly assist the electrician, plumber, HVAC Firm or Insulation Company in causing almost no damage or patchwork inside. If you can re-assess your overall plans for the place you may find better results with proper phase planning & execution.


I had my 1913 3 story row home completely rewired to remove the knob/tube. As stated above, it was mostly ceiling lights that required the most damaging work. But I was amazed how few and how small the holes in the walls and ceilings were. My contractor filled them when they were done. My advice; hire somebody experienced in this kind of work.

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