Mike Dolt Enterprises
Mike Dolt Enterprises
User: mayjong, Location: Ohio
Asked on: Friday, March 18, 2011 at 12:47 pm EDT
Answered on: Tuesday, May 14, 2024 at 2:59 am EDT
Question: hey all- been a long whilei thought i had the answer to this one, (but i made the mistake of opening the book to check my answer!) 2008 NEC-200A panel. contractor wants to use a 20A breaker (with 8 gauge wire)to power a 40A subpanel (for lights and plugs in a workshop)my question is about the 20A, "feeding" a 40A panel.is this a code compliant install? section?thanks!
Code Compliant
No
Section
NEC 240.15(B)
Explanation:
The overcurrent protection (OCP) for a branch circuit must not exceed the ampacity of the conductors supplying the circuit. In this case, the 20A breaker has an ampacity of 20A, while the subpanel is rated for 40A. This means that the breaker would not provide adequate protection for the subpanel and the conductors feeding it.According to NEC 240.15(B), the OCP for a branch circuit supplying a subpanel must be rated not greater than the rating of the subpanel or overcurrent device(s) protecting the subpanel. In this case, the 20A breaker exceeds the rating of the 40A subpanel and is therefore not compliant with the NEC.To make the installation code compliant, a 40A breaker must be used with 8 AWG wire. Flag for review