Quote:
Originally Posted by jr_tech
Interesting history of wiring practice in the US:
https://wenatcheehomeinspection.com/..._the_USA-1.pdf
From above source:
“Nonmetallic Cable
Although nonmetallic-sheathed cable, or NM for short, was first listed and described in the NEC in 1926, it was actually invented a few years earlier by General Cable at their Rome Wire Division in Rome, NY, and marketed under the trade name “Romex®.” Today many installers still refer generically to NM cable as Romex. Early NM cable had their individual conductors jacket wrapped in a cotton braid that was impregnated with either a varnish or tar-like substance for moisture protection.
Around 1950, synthetic spun rayon was being permitted to replace the cotton thread in the jacket braid. Then in the early 1960’s, thermoplastic began replacing the braided jacket altogether, and by about 1970, most all NM cable had a PVC outer jacket, even though a braid was still permitted until 1984. Also in 1984, NM-B cable was developed and required to have 90°C rated individual conductors, and a 75°C outer jacket (see Fig. 4).
Until the early 1960’s, most NM cable for residential use did not have a grounding conductor. However, changes in the 1962 Code that mandated equipment grounding for all branch circuits popularized the use of NM cable with ground. Earlier versions of NM cable with ground permitted the grounding conductor to be No. 16 AWG for 14 and 12 gauge copper NM, and No. 14 AWG ground for 10 gauge copper NM. In 1969, new requirements no longer permitted an undersized grounding conductor for 14, 12 and 10 gauge NM cable.”
jr |
It's a very informative website!
I not that familiar with Romex wiring after living in Milwaukee, county Wisconsin for 58 years. Romex was not allowed until the mid 70's.
I lived in three different old houses that were wired for electricity many years after they were built. They were wired in the mid 20's and it was all BX cable.
It was my understanding that the Electric Company subsidized the installation.