I have an underground wire that I think is called #8-3 but I can't find any
numbers on it. The OD of the insulation is 0.238" on each of the three
wires. That in turn is in another insulated jacket for underground. Each
wire is a seven stranded unit, the O.D. of this is 0.145" and each wire
measures 0.048". What's the wire size here?

More importantly, I need to know amp capacity. There's four of these #8?-3
wires in a conduit for four feet going from the main to underground.
(Multiconductor may reduce amp rating?)

I want to go 40 amp circuit breaker. Am I OK

Karl