How To Look At A House
McGarry and Madsen's home inspection blog for buyers of
site-built, mobile/manfuactured and modular homes
When did knob and tube wiring stop being used in homes?
Monday, March 11, 2019
"Knob and tube" was the most cost-effective way to wire a home from about 1880 to the 1930s. It began gradually being phased out through the 1940s, displaced by electrical cables that bundled hot and neutral, and eventually ground, wires in a single flexible sleeve. We have not seen any homes built in 1950 or later with K&T in Florida.
If a home has knob and tube wiring still functioning, or porcelain knobs or tubes abandoned in place in the attic or crawl space, that indicates it is pre-1950 construction when the actual date of construction is unknown. A home we recently inspected was listed as built in 1990, but one of the ways we were able to show the buyer that was a much older house that had been moved to the site and remodeled was the abandoned porcelain knobs and disconnected wires in the crawl space.
To learn more about it, see our blog post What is "knob and tube" wiring?
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