Fine strand cable for wiring from panels or 6 strand 10ga I can get for free?

[Withalligators]

Hey folks,
I've been posting a ton of questions and everyone is being so helpful. I'm working at a solar field right now, but get different answers from all of the electricians on site. They are using 10ga cable from the panels to the boxes, but the strands are extremely thick. There are only 6 strands in it.
I have 3 x 327w panels on my van. Will I benefit from getting some finer stranded stuff, or is this good enough? I can get what I need from here from damaged runs and splice MC4s onto each end.
Cheers
Alex

[Mike90250]

Fine stranded handles flexing better than coarse. Coarse handles corrosion better. Most lugs and crimps are set for the coarse strand cable, fine strand needs slightly different lugs and crimp dies.

[Withalligators]

What about loss? I hear with lower voltages more of the current is on the outside of copper strands and thus with less strands you lose some current. Negligible?

[Sunking]

What about loss? I hear with lower voltages more of the current is on the outside of copper strands and thus with less strands you lose some current. Negligible?

No difference. A 6 AWG cable is a 6 AWG cable. Both have roughly the same resistance. The exception is 400 Hz power used in ships and planes from Skin Effect. DC and AC 60Hz power does not have Skin Effect. Sparkies do not like working with finer strands because it is expensive, requires extra sill and time, and exposes the contractor to greater liability risk with failures.

What you are talking about is wire stranding class. Most of what you see in box stores is Class B Stranding and Solid. Your home is most likely is wired with solid.. Once you get up to 10 AWG is where sparkies switch to Class B stranding because it is easier to work with.

The finer stranded wire are Class C, D, G, H, and I with I being the finest strands.

WARNING. Finer stranded cable is a wonderful thing, but much more difficult to terminate properly. The terminals are a different size and require some specialized expensive compression tools. To start with a lot more care must be exercised stripping the wire skinner. It is extremely easy to score the wire when you strip it and thus will cut the outer layer of strands off reducing the wire size. Terminals will not fit snugly and that means fire risk. Finer stranded wire diameter is smaller and requires terminals with longer compression barrels. The wire and terminals are considerable more expensive and require more skill to terminate.

If you are going to use a finer strand I would suggest you shop at either a Marine Supply shop or Ham Radio Shop. Even a better idea is have a Marine Shop Terminate the cables for you as they have the tools and experience. The reason I say this is Marine Standards are more strict than NEC. The cable insulation have higher temperature ratings, oil and gas resistant, and a softer more flexible insulation. Finer strands are designed to use where either extreme sharp bends are required, and where high vibrations like machinery exist causing metal fatigue. All excellent reasons to use in an RV. But be warned if done improperly if a failure waiting to happen that can result in a fire. Something like this.

[neweclipse]

Just a FYI: 19 strand wire is very common and is a standard size in all respects for terminating. THHN and THWN are very common examples of 19 strand wire.

[Sunking]

For more info on wire stranding this link lays it out.