Conductor Sizing

[Designer371141]

Can you apply the 90C ampacity of wire for sizing when your lugs are all only 75C rated, example; tri-plex XHHW cable, installed in duct bank, requirement is for 1000amps, the lead engineer is applying the 430 amp rating of the 90C in Article 310.15 and derating for 104F temperature to meet his needs, utilizing only three parallel runs. Is this

 

[Beaches EE]

Yes, you can.
110.14(C) Temperature Limitations. The temperature rating associated with the ampacity of a conductor shall be selected and
coordinated so as not to exceed the lowest temperature rating
of any connected termination, conductor, or device. Conductors
with temperature ratings higher than specified for terminations
shall be permitted to be used for ampacity adjustment,
correction, or both.

 

[augie47]

But keep 110.14 in mind. In the end, after de-rating, your ampacity can not exceed the allowed ampacity based on the equipment at termination. If you terminate at 75° gear, you can['t exceed the 75°C ampacity.

 

[Designer371141]

Thank you for the references and the information, this has resolved more than one issue associated with our project.