Depending on insulation "type" it can't be 8 times (or 12) any closer than the existing size of itself,
it can't be any closer than that to it's exist diameter, so the size of the wire 8 times can be no closer than that to itself, use the sum of that as the allowable radius...
Ex.
.6875 x (8 or 12) =
Think no closer than it exists 8 or 12 times, as your looking at it ...