I've seen a few mentions of stranded wire being bad for a ground system.
On the positive side, I'd think that the stranded wire would have a bit
more connection with the surrounding earth since it has more surface area.
On the negative side, there is a bit less copper in a stranded wire.
Also, the increased surface area would probably cause the wire to
corrode a bit faster.
On the speculative side: Initially, there probably wouldn't be any great
improvements due to skin effect with stranded wire since the strands are
not insulated. However, if the surface of the strands gets ozidized,
this would increase the effectiveness of the strands by encouraging the
current to stay in any given strand.
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