Is there a standard for marking (+) and (-) paired LV DC wiring (e.g. speaker wire, 12V car wire).
For instance, with some paired cable, one wire is striped, ribbed, etc.
Thanks!
This is a manufacturing and listing issue. For example a multipair cable is available with one of several color coding systems. The Belden wire catalog has a chart in the technical information section that lists 8 color codes, some are standards of the Insulated Cable Engineers Assocation.
But yes, cables frequently have markings on the each wire.
For instance, with some paired cable, one wire is striped, ribbed, etc.
I think you are talking about "zip" cord. It's not a permissable wiring method within structures even for low voltage. Where used for it's intended purpose there is no standard though many lamps and fixtures seem to use the rib side as neutral.
400.22 Grounded-Conductor Identification. One conductor
of flexible cords that is intended to be used as a
grounded circuit conductor shall have a continuous marker
that readily distinguishes it from the other conductor or
conductors. The identification shall consist of one of the
methods indicated in 400.22(A) through 400.22(F)........
(F) Surface Marking. One or more ridges, grooves,
white stripes located on the exterior of the cord so
identify one conductor for cords having insulation
individual conductors integral with the jacket.