Stranded
Flexibility
Stranded wire is more flexible than solid core wire, which makes it well suited in situations where there will be movement of the wire. It also makes routing the wire through a building a bit easier.
Higher resistance to metal fatigue
Where solid core wire will weaken and break, stranded wire holds up to being bent repeatedly.
Solid
Cheaper to manufacture
While this savings may or may not be passed on to the consumer, solid core wire is cheaper to make.
More rugged
Solid wire resists cutting and stretching damage better than stranded wire.
Lower resistance
Given a solid and stranded wire of the same diameter, the solid wire will have a lower resistance. This is because there will always be gaps between the strands of a stranded wire. A stranded wire of the same gauge, will have a larger diameter than a solid wire to compensate for this. When you buy wire, you'll always buy it based on gauge. Both solid and stranded wires will have the same resistance, the stranded will simply be a bit larger in diameter.
Easier to terminate
If you're not careful when stripping stranded wire, you can end up cutting off strands (usually only a problem with smaller gauge wire, or wire with lots of strands). Depending on the number of removed strands, the ampacity of the wire can be negatively affected. Though nicking a solid core wire while stripping can make the wire more susceptible to breakage, so this isn't a clear cut advantage.
Solid core wire can be used in push in ("backstab") terminals, more often than stranded. This can be a pro or a con, depending on who you talk to.
Stranded wire can be more difficult to terminate on screw terminals, as you can sometimes have escapee strands which don't end up under the screw. This again can affect the ampacity of the wire.
Because stranded wire has a larger diameter, it tends to fill up twist-on wire connectors faster (less wires allowed in the connector).
Unless there's a lot of movement within the home (RV, house boat, frequent earthquakes), or you're pulling the wire through conduit. I'd say there isn't much of a difference either way.
The trade answer is a toner and probe, it is also the easiest.
An amazon search for ' telephone tracer ' will show a range of products I am talking about.
A toner is the tool that the phone company supplies to their employees that need to find a specific pair of wires in a cable, or inside a wall. Other places use them too.
The tool is art meets science if you are looking for 1 pair of wires in a bundle of 100, but if you are just looking for a cable, they are fairly easy.
This can also be used to find DEAD - NO POWER - outlets/breakers
Best Answer
It is rough-in for central vacuum. Pipe and two wires for distant turn on vac. Some special outlets, central vacuum should be installed if you gonna use it. And hoses, connected to outlets, have switches.