NEC Table 310.15(B)(16) or manufacturers spec sheet

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janssen_l

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Rochester Hills, MI, USA
Gentlemen,

This is my first post here and I'd like to thank everybody in this forum who is providing help, I found already many great explanation for the NEC in here, kudos.
Now to my question:

Situation:
  1. I want to use two cables type "Gexol 37-102-317VFD" in parallel for the connection between the VFD and the motor this is a 2/0AWG and has the following temperature ratings: 110°C (201A), 100°C (188°C), 90°C (173A) & 75°C (145A) for an ambient temperature of 45°C.
  2. The motor has a rated current of 265A, no hp rating.
  3. My VFD has no temperature rating.
  4. The cable runs through 55°C ambient temperature.

My thoughts:
  1. cable needs to be 125% of 265A = 331,25A as per NEC 430.22
  2. as per NEC 110.14(C) my ampacity needs to meet the requirements for both the termination as well as for the cable insulation
  3. NEC 110.14(C)(1) & 110.14(C)(1)(b) tells me to look for the termination ampacity to Table 310.15(B)(16) column 75°C (above 100A) and not in the manufacturers spec sheet. As no correction or adjustment factor is used on the termination calulation, for 2 cables 2/0AWG that makes 2*175=350 > 331,25A -> looks good
    Question #1: Does it matter that the cable spec sheet gives an ampacity of 145A@75°C? 2*145=290A < 331,25A -> doesn't look good
  4. For "base ampacity" of the cable I use the manufacturers spec sheet: 2*201=402A > 331,25A
    Question #2: Is that correct or do I have to use Table 310.15(B)(16), what is the spec sheet then good for???
  5. For temperature correction factor I use the equation given in 310.15(B)(2), as the table 310.15(B)(2)(a) doesn't have values for 110°C
    SQUAREROT((110-55)/(110-45))=0,9198
    Question #3: Am I using that equation correctly?
  6. I have no adjustment factor for more conductors as my cable contains only 3 current carrying conductors and I space the two cables in my cable tray with one cable diameter distance as per 392.80(A)(1)(c)
  7. Makes an overall ampacity for the cable of 2x201x0,9198=368A > 332A -> looks good
    Question #4: was all above correct?

Thank you for your replies!

Best regards,
Lukas
 
I might suggest you check with your AHJ for approval. The cut sheet I show is "UL listed for Shipboard Installation"
 
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