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Can Type XHHW-2 insulated conductors be ran in conduit on the roof without being subject to the Adjustment Factors for Ambient Temperature noted in Table 310.15(B)(3)(c)? 

Question asked by andrew_rogers on Sep 15, 2016
Latest reply on Dec 10, 2016 by jhren1

Per the Exception noted at Table 310.15(B)(3)(c), XHHW-2 insulated conductors "shall not be subject to the ampacity adjustment" noted in the Table. 

 

 

Yet, in the application example provided in the 2014 National Electrical Code Handbook, XHHW-2 is used to demonstrate the impact of applying the adjustment factor noted in the Table which results in an "18% loss of usable conductor ampacity."

 

 

Is this an oversight?  Or are we misunderstanding the Exception.  Can Type XHHW-2 insulated conductors be ran in conduit on the roof without being subject to the Adjustment Factors for Ambient Temperature noted in Table 310.15(B)(3)(c)?

 

 

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