Gustafson said knob-and-tube was phased out by the 1930s.As it ages, he said, it will wear down from the current going through it, especially at the connections.upgrades needed to our 1920s Chicago-area 4 square house, we're considering re-wiring our house that has knob and tube wires and plaster walls throughout. Also - I've heard some electricians will only do time and materials estimates.
History Behind the Walls Prior to the 1900s, builders installed knob-and-tube wiring, said Glenn Gustafson of the Bergen Home Wright, Oradell (bergenhomewright.com).They would nail ceramic, insulated knobs to the sides of joists in a house’s frame.Rough estimates are not possible for the reasons you mentioned, too many variables.Your location, permits, availability and quality of contractors, condition of your walls etc all play into factor.I have 36", 60" and 72" bits and assorted "Fish" tape.
There are also junciton boxes that make adding one a snap for old work...Someone told us that because we have plaster walls this is a big deal. That sounds more like a breaker or receptacle problem than a wiring problem. If you do need rewiring most interior wood frame walls are hollow and wire can be fished through, though it may be necessary to make small openings here and there to fish from floor to floor or around duct work, plumbing, or other obstructions.We were under the impression that the electrician could just thread the new wiring through the wall but our friend told us they have to tear down the plaster walls. Are we really looking at having to go through putting up new walls in addition to new wiring?! If your electrician says otherwise, visit with a different craftsman.New wiring can be "snaked" through walls and ceilings but it is tricky and time consuming; thus expensive.It is a necessity as most old houses have a 60 amp service, knob & tube wiring designed for a few light bulbs and perhaps a radio and vacuume sweeper!How long do such projects typically take if done full time and how many people usually work on it - 1, 2 or more people?