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The smooth one is coax. I'm asking about the braided ones.

They're power, running from a metal junction box in my basement ceiling up to an outlet just above the pictured floor boards.

It's an old house, with lots of knob and tube. The box where this originates is fed by EMT.

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    Are the braided lines flat, or completely round? Can you tell how many conductors are inside? – Daniel Griscom Mar 28 at 2:48
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    Round. One wire inside each (solid core, sheathed). – philo Mar 28 at 3:24
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It is unusual for single conductor with cloth braid to be used except for feeder wiring like that. Cloth braid was common up to the 50’s but normally there were 2 wires in the cable when run loose. knob and tube also ran single insulated wires down walls but normally maintained separation of the conductors and was not allowed to wander like or to use the same hole through a wooden member . so it may have been a diy job of old or a addition to the system,

many states did not have the strict rules we have today even though the national electric code was established pre 1900 it Was probably an addition. If both wires enter the metal box in the same hole that would be more evidence that it probably was a later modification.

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    The EMT points to DIY too. Not much EMT in K&T.+ – JACK Mar 28 at 13:57
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    Those are def. knob and tube conductors. Probably part of the system was upgraded at some point with EMT and parts left original. Ed is right in that allowing them to run loose like that isn't correct. The old cloth/rubber insulation (before plastic was available) isn't that good an insulator and subject to deterioration which is why physical separation was important, why its not in a cable and is supported by insulators: Knobs for turns and corners and tubes going thru wood! Replace where possible and be sure any junctions/splices are properly made in boxes and permanently accessible. – George Anderson Mar 28 at 16:30
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So, that braided outer is pretty common in shorter lengths to keep discrete conductors (hot or neutral) separate when the wires jump off their anchoring knobs. It's most common (in my experience) as a shield coming into a junction box.

If you wanted to do anything about it, you could replace the two strands with a romex-type of modern wire. You'd have better wire to work with at the outlet.

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