Peter, Howar,
Below is a link to UL.
www.ul.com/lancable/index.html
I might be wrong but the original statement was: UL apparently requires that the conductors (dia. 0.33 – 0.65”) have a label applied, in ring form, every 10 feet.
I have been wondering about this since the first posting. First off UL is usually only intersted in insulated products. Once a conductor is designated for an insulated product they are concerned that it meets standard. When it is just bare wire on a reel, I don't think that they are really interested in bare wire.
Additionally how impractical could it be. You want to insulate some stranded conductor so you buy it and then have to remove the label located every 10 feet so you can extrude it?? When you think about it, it does not make sense (doesn't mean it doesn't happen, it just doesn't make sense.)
I could not find anything on their web site about labeling bare stranded conductor.