Table C.9 or C.9(A)?

[NetNathan]

What is the difference in "concentric stranded conductors" and "compact stranded conductors"? Cannot seem to find definition in NEC.
"Concentric" uses Table C.9 and the "compact" uses Table C.9(A).
Both tables reference XHHW-2, so I must be able to get the same insulation.
If I order 4/0 XHHW-2.....how do I know if it is "concentric" or "compact"...which type is "standard"?
I will be using copper wire, not aluminum.

 

[GoldDigger]

What is the difference in "concentric stranded conductors" and "compact stranded conductors"? Cannot seem to find definition in NEC.
"Concentric" uses Table C.9 and the "compact" uses Table C.9(A).
Both tables reference XHHW-2, so I must be able to get the same insulation.
If I order 4/0 XHHW-2.....how do I know if it is "concentric" or "compact"...which type is "standard"?
I will be using copper wire, not aluminum.

The NEC does not have to define it because the distinction is in the UL specifications for the listed wires and cables involved.

The difference is in the cross section of the individual wire strands making up a wire or cable.
In concentric the strands are round in cross section leaving empty space between the strands when they are twisted or pressed together.
In compact the assembles unit of strands is compressed enough to change the shape of the strands to minimize the empty space, making for a smaller diameter for the same metal cross sectional area.

Most large gauge aluminum wire is compact stranded these days. Less common with copper.
To know what you have you need to look at the description of the wire/cable.

PS: Compressed is midway between concentric and compact.
You can see a good description, with illustrations, at https://www.anixter.com/en_us/resources/literature/wire-wisdom/conductor-strand-types.html

 

[infinity]

I would call concentric "standard". Compact conductors have all of the intersticies between the conductors removed and are therefore smaller than standard conductors of the same size.

 

[NetNathan]

Thanx guys...

 

[iwire]

https://www.anixter.com/en_us/resources/literature/wire-wisdom/conductor-strand-types.html