NEC User
Senior Member
- Location
- Marlboro, NJ, USA
If MC cables are being installed in an existing conduit:
Are the existing conduit considered sleeves or raceways?
In my opinion they would be considered a raceway since being in an enclosed space constitutes conditions where ambient temps and conductor fill may affect performance and thus derating tables for ambient temp and multiple conductors installed in one raceway may need to be employed. Although each cable may not contain more than "3 current-carrying conductors", installing more than one cable in the conduit constitutes more than 3 conductors in the raceway and thus table 310.15(B)(3)(a) should be employed for derating ampacity.
Your thoughts?
Are the existing conduit considered sleeves or raceways?
In my opinion they would be considered a raceway since being in an enclosed space constitutes conditions where ambient temps and conductor fill may affect performance and thus derating tables for ambient temp and multiple conductors installed in one raceway may need to be employed. Although each cable may not contain more than "3 current-carrying conductors", installing more than one cable in the conduit constitutes more than 3 conductors in the raceway and thus table 310.15(B)(3)(a) should be employed for derating ampacity.
Your thoughts?
