Spacing of 5kv unsheilded conductors inside MV switchgear

[QESken]

Utilizing the unshielded exception for conductors over 2400 volts which are part of a MV switchgear assembly. We installed 15kv rated #12 wire from main bus to the primary side of a PT. The wire is supported on fiberglass. But all three phases are in close proximity to each other. The AHJ is rejecting and requiring phase to phase spacing for these conductors of 9" and phase to ground of 6" (this is a 13,800VAC application). I do not understand why insulated wire would require air gap spacing as if it was bare bus. I realize at this voltage capacitive coupling could be relevant and some spacing would be advantageous but is it required by code? None of this wire leaves the switchgear cabinet.

 

[Fulthrotl]

Utilizing the unshielded exception for conductors over 2400 volts which are part of a MV switchgear assembly. We installed 15kv rated #12 wire from main bus to the primary side of a PT. The wire is supported on fiberglass. But all three phases are in close proximity to each other. The AHJ is rejecting and requiring phase to phase spacing for these conductors of 9" and phase to ground of 6" (this is a 13,800VAC application). I do not understand why insulated wire would require air gap spacing as if it was bare bus. I realize at this voltage capacitive coupling could be relevant and some spacing would be advantageous but is it required by code? None of this wire leaves the switchgear cabinet.

is this PT part of the UL listed assembly? if it's an add, i'm suspecting rules may
be different than part of a listed switchgear assembly.

 

[QESken]

We are the manufacture of the entire switchgear assembly
It is a custom piece which does not conform to our listed design so it is not a listed unit.
The unshielded conductor is listed for 15KV as are all of the other components.
We have never been required to space insulated conductors at air gap distances.
I just can't see where the code states that I have to ignore the insulation rating of the cable.