Results 1 to 10 of 10

Thread: Individual Branch Ciruit

  1. #1
    Join Date
    Feb 2013
    Location
    Aspen, Colo
    Posts
    2,010

    Individual Branch Ciruit

    2 -50 amp appliances. 1 - range & 1- steam unit. Contractors has only one 50 amp circuit and wants to use a manual transfer type switching that would allow only one of the appliances to be energized at a time. Both appliance require an individual branch circuit.

    Does the contractors proposal comply with the NEC?

    If so please be specific
    CircuitRyder --- Unfortunately not all good ideas are code enforceable.

  2. #2
    Join Date
    Jan 2007
    Posts
    3,773
    I personally have never seen anything wrong with selective load shedding myself.

    JAP>

  3. #3
    Join Date
    Jun 2016
    Location
    Tampa, FL, USA
    Posts
    1,767
    Nothing wrong with doing that, but a manual transfer switch may be overdoing it. A subpanel with two 50 amp breakers (one for each device) is probably sufficient. If the feeder to the subpanel can only handle 50 amps, the breaker for the subpanel will trip if both devices are used simultaneously.

  4. #4
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    26,031
    Quote Originally Posted by Coppersmith View Post
    Nothing wrong with doing that, but a manual transfer switch may be overdoing it. A subpanel with two 50 amp breakers (one for each device) is probably sufficient. If the feeder to the subpanel can only handle 50 amps, the breaker for the subpanel will trip if both devices are used simultaneously.
    Does the feeder to the sub-panel need to be sized according to the calculated load?
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  5. #5
    Join Date
    Feb 2003
    Location
    Seattle, WA
    Posts
    19,149
    It's not selective load shedding, it's selecting a load.

    Unless it's Friday and I am getting too ready to head home and am thereby forgetting something, I will say that the NEC never requires an individual branch circuit. It allows them, and allows you to bypass other rules if you use them, but I can't think of a circumstance in which it is required. Example: kitchen outlets must be on 20 amp circuits, except that you can power the fridge with an individual 15 amp branch circuit.

    Now a separate issue is whether you would be violating the manufacturer's requirement for an individual branch circuit. I say no, because with the manual switch in either position, the load that is thereby selected is not sharing the circuit with any other load.
    Charles E. Beck, P.E., Seattle
    Comments based on 2017 NEC unless otherwise noted.

  6. #6
    Join Date
    May 2018
    Location
    Jamaica and london
    Posts
    775
    Rob, isnt that like when we size based upon heating and cooling? We take the largest of the two...so in this case the two are identical...
    a Sub Panel sized at 50 amps with only two breakers, both of them being 50 amps... may seem to be overloaded but it definitely should trip if both are used at same time.
    However, if one can run the cable for it, would prefer to run 100 amps to the sub panel and then allow the two 50 amps from there... is it a case of the panel being full? Or the service itself being full?
    Student of electrical codes. Please Take others advice first.

  7. #7
    Join Date
    Jun 2016
    Location
    Tampa, FL, USA
    Posts
    1,767
    Quote Originally Posted by infinity View Post
    Does the feeder to the sub-panel need to be sized according to the calculated load?
    I think it is if the intention is to only have one 50 amp load energized (by selecting the correct breaker) at a time.

  8. #8
    Join Date
    Apr 2003
    Location
    Fort Collins, Colorado
    Posts
    1,693
    Quote Originally Posted by mwm1752 View Post
    2 -50 amp appliances. 1 - range & 1- steam unit. Contractors has only one 50 amp circuit and wants to use a manual transfer type switching that would allow only one of the appliances to be energized at a time. Both appliance require an individual branch circuit.

    Does the contractors proposal comply with the NEC?

    If so please be specific
    I say it complies with the NEC as there is nothing to prohibit the install.
    I hope you are well, mwm!
    Ron

  9. #9
    Join Date
    Jan 2007
    Posts
    3,773
    Quote Originally Posted by charlie b View Post
    [SIZE=4][FONT=times new roman]It's not selective load shedding, it's selecting a load.
    That all depends on what side of the transfer switch your looking at Charlie......


    JAP>

  10. #10
    Join Date
    Jul 2003
    Location
    New Jersey
    Posts
    26,031
    I like the sub-panel idea but I don't see how you get around this section when the two loads are connected to the sub-panel.

    215.2 Minimum Rating and Size.
    (A) Feeders Not More Than 600 Volts.
    (1) General. Feeder conductors shall have an ampacity not
    less than required to supply the load as calculated in Parts
    III, IV, and V of Article 220. Conductors shall be sized to
    carry not less than the larger of 215.2(A)(1)(a) or (b).
    (a) Where a feeder supplies continuous loads or any
    combination of continuous and noncontinuous loads, the
    minimum feeder conductor size shall have an allowable
    ampacity not less than the noncontinuous load plus
    125 percent of the continuous load.

    (b) The minimum feeder conductor size shall have an
    allowable ampacity not less than the maximum load to be
    served after the application of any adjustment or correction
    factors.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

Posting Permissions

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