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Power Question

Discussion in 'Lighting and Electrics' started by Tyler, Dec 16, 2008.

  1. Tyler

    Tyler Member

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    Last edited: Nov 9, 2009
  2. ship

    ship Senior Team Emeritus Premium Member

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    a bit of a hack way of doing the distro & civilian as it were way of defining it, but a maximum of 30A per leg of power. Three sets of outlets per leg at 30A. 60A total if both legs added together.


    Realistically I would keep to 80% of that maximum loading and attempt to balance my load between the two phases as best possible.

    Use all three receptacles @80% of 10A per receptacle per leg for a total of 6 receptacles at 8A each, or use two receptacles per leg @12A each for a total of four receptacles on both legs of power and don't use the extra receptacles...
     
  3. Malabaristo

    Malabaristo Active Member

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    To me it sounds like they did it wrong:
    I would interpret what they said as two 30 amp circuit breakers (or fuses) with three edison duplex outlets connected to each circuit. Edison outlets are only rated at either 15 or 20 amps depending on whether the blades are parallel, or if one of them is turned sideways. Having 15A or 20A outlets fed by a 30A breaker is not particularly safe or legal. It would be a good idea to have a qualified electrician take a look at this "distro" to make sure it meets code.
     
  4. ship

    ship Senior Team Emeritus Premium Member

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    Agreed sounds sketchy and the details could be for something proper or wrong, but if I remember the NEC correctly you can have a 30A breaker/fuse circuit if a few 20A receptacles fed by it in a way similar to having a 20A breaker feeding a few 15A outlets. I'm sure someone will verify that's the case yes if say wired by 10ga wire or other means ... but not really the proper way to do it as intended either. Thinking more likely some form of company switch that someone tapped for adding a few outlets to. If that's the case I'm unsure on it's code compliance in a general concept of the box should have been replaced and a sub panel with individual breakered outlets should have been installed.

    Details of the power distro I'm on the fence about in being something sketchy to be concerned about or possibly ok but probably not due to sufficient circuit protection etc. short of specific details or seeing it. Wasn't going there in general, just stating the distribution concept in general but good point taken up on concern for safety.
     
    Last edited: Dec 16, 2008
  5. FMEng

    FMEng Well-Known Member Fight Leukemia

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    I believe that Ship is correct. The fuse size is to protect the wire feeding the receptacles, not the receptacles themselves (within reason). You can load any duplex plug up to 15 amps, for a total 24 amps (80% of 30 A) per leg.
     
  6. TimmyP1955

    TimmyP1955 Active Member

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    I believe that the breaker or fuse must be no larger than the capacity of the lowest rated device on the line. So if 10 gauge wire (which is rated for 30A) feeds 15A duplexes, the circuit would have to be fused at 15 Amps, no matter the number of 15A duplexes.
     
  7. mrb

    mrb Active Member

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    having anything smaller than a 30a receptacle on a 30 amp circuit is not to code, nor is it safe. Here is an outline of what is allowed:

    15a breaker - one or more 15a receptacles
    20a breaker - single 20a receptacle
    20a breaker - multiple 20a receptacles
    20a breaker - multiple 15a receptacles

    The circuit breaker is not just there to protect the wiring supplying the receptacle, is is also there to protect the device as well as what is plugged into it to some degree. You cannot supply a duplex 15a receptacle with a 30a breaker.

    This is for reference only, consult applicable codes and hire a licensed professional or other qualified individual for all electrical work.
     
  8. SteveB

    SteveB Well-Known Member

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    Duplex receptacles are rated for either 15 amps or 20 amps, and the description you've been provided indicates a code violation.

    The overcurrent protection must be of the same rating, or smaller, then any permanent device connected.

    Doesn't matter how many devices - which in a residential application can be as many as 7 devices downstream (example I read was 7 receptacles in a living room on a 15 amp breaker). The breaker can not be of a higher rating then either the wire or the device.

    SB
     
  9. mrb

    mrb Active Member

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    the exception to this is you can put multiple 15a receptacles on a 20a breaker, but not a single 15 on a 20a breaker. I dont remember if that applies to one duplex, or a single receptacle, i think its just a single receptacle.
     
  10. FMEng

    FMEng Well-Known Member Fight Leukemia

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    I stand corrected. MRB is quite correct.
     
  11. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Noting all numbers presented are out the window in Aus or other non US places...
    I can't remember where in AS3000 the numbers are off the top of my head, but I'm sure they'd turn a few heads...
     
  12. CavezziMagnum

    CavezziMagnum Member

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    60Amps over 220? Sounds like a dryer plug to me. How do you wash the costumes?
     
  13. ship

    ship Senior Team Emeritus Premium Member

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    You are correct (thanks for the correction.) - Article 210. My mistake or perhaps a really old code book on this detail I had remembered before a later change. 20A is permissible for 20A or a few 15A under specific conditions, but 30A overcurrent protection is single 30A device only and no multitudes of 20A I thought I remembered. Yep, against code to do that.
     
  14. SteveB

    SteveB Well-Known Member

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    Thanks for the follow up, I got busy with Nutcracker and never had time to look up what I was referring to.

    SB
     
  15. jmac

    jmac Active Member

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    Above per MRB is all correct, by NEC. The duplex recepts. need 20 amp protection in lieu of 30 amp.
     
  16. ship

    ship Senior Team Emeritus Premium Member

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    thought of mine was origionally that you could supply a series of 20A not 15A receptacles by 30A breaker under certain conditions. Remember the origional post said Edison not what amperage of it.

    Anyway, 30A to supply other than single device 30A receptacle is not proper.
     

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