Page 2 of 2 FirstFirst 12
Results 11 to 18 of 18

Thread: Feeder Sizing

  1. #11
    Join Date
    Sep 2012
    Location
    NJ
    Posts
    2,098
    Quote Originally Posted by infinity View Post
    Then use the "weakest link" for the feeder, if the switch is 200 amps but the panel or fuse size is 125 amps then the feeder needs to only be 125 amps.
    Thank. I thought there would be hard and fast rules(NEC) for sizing the conductors. Calculated load, fuse, breaker etc. Seem like you are assuming( although I know probably right...)

  2. #12
    Join Date
    Sep 2012
    Location
    NJ
    Posts
    2,098
    Quote Originally Posted by petersonra View Post
    I agree. Use whatever the OCPD rating is.
    I understand but technically is you have a switch at a certain amperage and a fuse in the switch which OCPD are you referring to the switch size or fuse. I understand others have said fuse size...trying to be clear on what your saying. Thanks.

  3. #13
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    25,584
    Quote Originally Posted by mstrlucky74 View Post
    Thank. I thought there would be hard and fast rules(NEC) for sizing the conductors. Calculated load, fuse, breaker etc. Seem like you are assuming( although I know probably right...)
    If you're given the switch size, the fuse size and the panel size there is no assuming. Size the conductors to fuse size.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  4. #14
    Join Date
    Sep 2012
    Location
    NJ
    Posts
    2,098
    Quote Originally Posted by infinity View Post
    If you're given the switch size, the fuse size and the panel size there is no assuming. Size the conductors to fuse size.
    Thanks! Which code section is this in?

    Sent from my SM-G955U using Tapatalk

  5. #15
    Join Date
    Aug 2004
    Location
    Northern illinois
    Posts
    16,843
    Quote Originally Posted by mstrlucky74 View Post
    Thanks! Which code section is this in?

    Sent from my SM-G955U using Tapatalk
    240 part I
    Bob

  6. #16
    Join Date
    Jul 2006
    Location
    San Francisco Bay Area, CA, USA
    Posts
    7,886
    The feeder conductors are sized based on the load. The fuses (OCPD) are sized to protect the conductors. The switch just holds the fuses, i.e. you can't physically put 450A fuses in a 400A switch, so you go to the next size up, a 600A switch.
    __________________________________________________ ____________________________
    Many people are shocked when they discover I am not a good electrician...

  7. #17
    Join Date
    Sep 2012
    Location
    NJ
    Posts
    2,098
    Quote Originally Posted by Jraef View Post
    The feeder conductors are sized based on the load. The fuses (OCPD) are sized to protect the conductors. The switch just holds the fuses, i.e. you can't physically put 450A fuses in a 400A switch, so you go to the next size up, a 600A switch.
    Got it and know those fuses won't fit. I'm following all the feedback but now you contradict what other have said by saying to size the conductors based on the load and not the fuses.

    Sent from my SM-G955U using Tapatalk

  8. #18
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
    Posts
    19,343
    Quote Originally Posted by mstrlucky74 View Post
    Got it and know those fuses won't fit. I'm following all the feedback but now you contradict what other have said by saying to size the conductors based on the load and not the fuses.

    Sent from my SM-G955U using Tapatalk
    Same difference? You size the conductors to carry the load (or more), then you size the fuse to protect the conductors (or smaller).
    You have the option to make both conductors and fuses larger, provided there is no code requirement to protect the load too (as with motor(s)).

    Sent from my XT1585 using Tapatalk

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •