Wire ampasities

[Cavie]

The Lead men in the company I just took over tell me that the local head electric inspector is makeing them use the 60 degree collum to size SEU cable. SEU is Xhhw so how is the inspector justifyng the use of 60 degree instead of 75?

 

[roger]

The Lead men in the company I just took over tell me that the local head electric inspector is makeing them use the 60 degree collum to size SEU cable. SEU is Xhhw so how is the inspector justifyng the use of 60 degree instead of 75?

338.10 Uses Permitted.(B) Branch Circuits or Feeders.(3) Temperature Limitations. Type SE service-entrance cable used to supply appliances shall not be subject to conductor temperatures in excess of the temperature specified for the type of insulation involved.(4) Installation Methods for Branch Circuits and Feeders. (a)Interior Installations. In addition to the provisions of this article, Type SE service-entrance cable used for interior wiring shall comply with the installation requirements of Part II of Article 334. 334.80 Ampacity.The ampacity of Types NM, NMC, and NMS cable shall be determined in accordance with 310.15. The ampacity shall be in accordance with the 60?C (140?F) conductor temperature rating. The 90?C (194?F) rating shall be permitted to be used for ampacity derating purposes, provided the final derated ampacity does not exceed that for a 60?C (140?F) rated conductor. The ampacity of Types NM, NMC, and NMS cable installed in cable tray shall be determined in accordance with 392.11.Where more than two NM cables containing two or more current-carrying conductors are installed, without maintaining spacing between the cables, through the same opening in wood framing that is to be fire- or draft-stopped using thermal insulation, caulk, or sealing foam, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a) and the provisions of 310.15(A)(2), Exception, shall not apply.Where more than two NM cables containing two or more current-carrying conductors are installed in contact with thermal insulation without maintaining spacing between cables, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a).

Roger

 

[eprice]

The Lead men in the company I just took over tell me that the local head electric inspector is makeing them use the 60 degree collum to size SEU cable. SEU is Xhhw so how is the inspector justifyng the use of 60 degree instead of 75?

In the 2008 NEC, for interior installation, Section 338.10 (B) (4) (a) requires you to follow Part II of Article 334. This would include 334.80 which requires the use of the 60 degree column. In the 2011 NEC, Section 338.10 (B) (4) (a) excludes the requirements of 334.80. The 2005 NEC also excludes the requirements of 334.80. I don't know if this was an error in the 2008. There is nothing in the margin to indicate that it was an intentional code change.

But, if your jurisdiction has adopted the 2008 NEC, this could be the justification.

 

[Cavie]

In the 2008 NEC, for interior installation, Section 338.10 (B) (4) (a) requires you to follow Part II of Article 334. This would include 334.80 which requires the use of the 60 degree column. In the 2011 NEC, Section 338.10 (B) (4) (a) excludes the requirements of 334.80. The 2005 NEC also excludes the requirements of 334.80. I don't know if this was an error in the 2008. There is nothing in the margin to indicate that it was an intentional code change.

But, if your jurisdiction has adopted the 2008 NEC, this could be the justification.

That would be it. I usd to work for the inspector so I know how he stays up at night looking for stuff like this. Thanks.