Mixing wires with different insulation

[drb7speed]

An Electrical Engineer was specifying wires for our circuit, running in cable tray.
Since he needed higher ampacity, he chose to use SRG (200 deg C insulation) wires.
"Manufacture's rating was 493 amps".

The problem that i have is that this cable tray is shared with thhn cables, 90 deg C insulation.
I am concerned that the thhn insulation we get damaged by the heat generated by the drg wires.

What does the NEC code say?

i found a section that said you need to use same insulation for each phase, for a single circuit, but
nothing about adjacent circuits...

 

[augie47]

I see a couple of problems beyond what you describe:
(a) SRG is not listed as a "Approved Conductor" by the NEC for Art 300 installations.
(b) 110.14 would still limit the conductor to the rating of the terminations.
(c) The only spec sheet I find states: Intended Use : 18-16 AWG per NEC 402 Fixture Wires. 18-4/0 AWG Leads for hazardous location motors or internal wiring of appliances.

 

[weressl]

An Electrical Engineer was specifying wires for our circuit, running in cable tray.
Since he needed higher ampacity, he chose to use SRG (200 deg C insulation) wires.
"Manufacture's rating was 493 amps".

The problem that i have is that this cable tray is shared with thhn cables, 90 deg C insulation.
I am concerned that the thhn insulation we get damaged by the heat generated by the drg wires.

What does the NEC code say?

i found a section that said you need to use same insulation for each phase, for a single circuit, but
nothing about adjacent circuits...

If the cable is not listed as one of the NEC approved cables for CT use, it can not be used. The cables must have TC rating stamped on them. THHN could also only be used if it is TC-rated.