Large cable spacing (NEC 2020)

[ElectricalKennedy]

Hi all,

First time posting but have used this forum to solve about 2 million problems, so thank you for all your advice and help.

I've got a question concerning cable separation in large scale solar installations...

There used to be a section in the NEC that dictated that single conductors had to be separated by the OD of the largest cable in order to remove derating factors. I cannot find anything similar in the 2020 NEC... have they removed it? I think it was like maybe.... Article 318?

Situation:

I have 8 x 500KCMIL 2kv PV conductors using a CAB style system (not cab though, cant remember the name of it) and there's no way to separate the cables naturally... cant find anything in 2020 NEC.... do I need to space them? or can I use a proverbial blade of grass to separate these things as there's no set requirement?

 

[ron]

Are these individual conductors or a multiconductor cable?
There are sizing for no spacing or with one cable diameter spacing. For example, see 392.80(A)(1)(c) and 392.80(A)(2)(c) or 392.80(B)(1)(2) and 392.80(B)(2)(2)

 

[infinity]

I have 8 x 500KCMIL 2kv PV conductors using a CAB style system (not cab though, cant remember the name of it) and there's no way to separate the cables naturally... cant find anything in 2020 NEC.... do I need to space them? or can I use a proverbial blade of grass to separate these things as there's no set requirement?

So these are in cable tray?

 

[ElectricalKennedy]

So these are in cable tray?

Going over ground in a CAB like / Messenger wire with hanger configuration... where the cables are stacked vertically... is vertically considered a 'layer' in 392.80?
I understand 392.80 to represent cable tray and has mention of messenger cable support but it's for cables in a triangular configuration... I'm just confused on how to appropriately space or derate cables stacked vertically (2-4 cables)

 

[pv_n00b]

There has not been a general spacing allowance in the NEC when a conductor can be treated as in free air and not require derates that I am aware of. It was not until the 2023 NEC that Free Air got a definition so people made up a lot of definitions that were not very good just so they could undersize conductors.
One thing I will add is that most people don't seem to be treating CAB type systems as messenger, and CAB is not tray. NEC 396 applies and 310.20 in the 2020 NEC has the ampacity for messenger supported conductor.
If it's not CAB it's probably AWM, that's the only other player in messenger for larger PV arrays.