:In addition to the fragility, a 90 year old home with the original wires would likely have knob and tube wiring instead of free-floating Romex-style power cable . ( Applicable words from the article " Currently the United States NEC forbids use of loose, blown-in, or expanding foam insulation over K & T wiring.
12.
It was used a lot when " wiring " meant actual, individual single-conductor wires in the walls ( see knob and tube wiring ), but it's no longer considered acceptable because, in some switch positions, it makes the " shell " of the light bulb base carry line voltage, potentially electrocuting a person attempting to change the light bulb.
