I’m 103 yo this January .
You said"If so reply explaining the difference with out using Google or other online source to answer the question…"
I use a book that ain’t cheatin.
I’m not an expert on the subject, but wouldn’t it have to relate to the size and shape of the conductors (solid strand or a bunch of strands ran together)?
All of the conductors I mentioned are stranded conductors. They do indeed vary in size (yet all remain the same ampacity rating). I will give it a bit more time to see if anyone wishes to tell me more…then I will explain why it’s good to know the difference.
Ok, Since I do not want to let this thread die without answering the question I will elaborate. I have to since I could be gone and not post again in months or years.
Concentric conductors have a larger approximate area then Compressed conductors which also have a larger approximate area than compact conductors. However, even with the reduced size, compact conductor maintain the same ampacity capacity as the overall larger concentric conductor of the same size.
The advantages are in things like raceway fill and decreased termination issues of people snipping the conductors to fit in lugs. However, also remember that typically lugs are sized to fit a conductor, if the lug was designed to fit 250 kcmil - 4/0 AL , you can bet that it was designed for concentric (standard stranded conductors) unless it says otherwise. So since a 4/0 AWG AL Compact conductor is smaller than a concentric, you have to be sure that the compact conductor can be used in that specific lug.
A simple call to the manufacturer of the lug can answer that question. Just things to know about conductors…that you never wanted to ask and probably never will again…lol