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Thread: how many outlets on a breaker

  1. #1
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    Thumbs up how many outlets on a breaker

    :-? what method of electrical calculation do you use to figure out, how many outlets to put on a 15 & 20 amp circuit breaker ?

  2. #2
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    Quote Originally Posted by Beverly
    :-? what method of electrical calculation do you use to figure out, how many outlets to put on a 15 & 20 amp circuit breaker ?
    Assuming (uh-oh!) you mean receptacle outlets, I use the "what's-the-load" method. Obvious are the single-receptacle circuits, like refrigerator, microwave, sump pump, central vacuum, etc. For kitchen counter receptacles, I like two or three.

    Since I try to keep receptacle and lighting circuits separate, I can put two or three bedrooms on one 20-amp circuit. A master bedroom and a family room would probably each get its own receptacle circuit.

    Direct answer: I'm not a believer that the load calculations directly translate to a specific limit on receptacle count. What if you decrease the spacing between them? If you want receptacles four feet apart, would one room require 5 or 6 circuits?
    Last edited by LarryFine; 12-10-06 at 12:34 AM.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  3. #3
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    3 watts per sq. ft. for residential... use 180va for other than dwelling...
    Last edited by stickboy1375; 12-10-06 at 12:33 AM.
    "Electricity is actually made up of extremely tiny particles called electrons, that you cannot see with the naked eye unless you have been drinking."

  4. #4
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    Larry you really wire bedrooms with #12 wire? IMO, I don't think I could justify that...
    "Electricity is actually made up of extremely tiny particles called electrons, that you cannot see with the naked eye unless you have been drinking."

  5. #5
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    Quote Originally Posted by stickboy1375
    Larry you really wire bedrooms with #12 wire? IMO, I don't think I could justify that...
    Lighting, no; receptacles, sometimes.

    In a typical 3-b/r, 1.5- or 2-bath house, one 15-amp lighting circuit for the bedroom/bath/hallway half and one for the kitchen/dining-room/living-room half. One 20-amp receptacle circuit supplies all of the bedroom and hallway receptacles, and a 15- or 20-amp circuit for the living-room and misc. (such as exterior and attic/crawl receptacles.)

    In the big (7800 sq.ft.+) that I've posted a few pix from, (every bedroom has its own full bath), I gave each bedroom/bathroom area its own 15-amp receptacle circuit and its own 15-amp lighting circuit (fan/light, recessed lights, closet light, bath vanity and fan/light combo). The homeowner paid for materials, by the way.

    When minimal materials cost is not top priority (and even when it is, if I can), I try to keep system performance in mind. The lights don't dim when the TV is turned on, or even a vacuum. I believe in sub-panels when practical, which also helps in minimizing voltage drop due to load diversification on feeders.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  6. #6
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    Quote Originally Posted by LarryFine
    Lighting, no; receptacles, sometimes.

    In a typical 3-b/r, 1.5- or 2-bath house, one 15-amp lighting circuit for the bedroom/bath/hallway half and one for the kitchen/dining-room/living-room half. One 20-amp receptacle circuit supplies all of the bedroom and hallway receptacles, and a 15- or 20-amp circuit for the living-room and misc. (such as exterior and attic/crawl receptacles.)
    How do you route that that it makes sense to have a separate lighting circuit? I think you have the right idea for reasons unrelated to cost, but in terms of having extra wires running around, that seems wasteful.

    When I lay out a bedroom, I take the home run to the light, 12/3 from the light to the switch, then exit the switch box out the bottom to the receptacles. If it's two small bedrooms I'll put the second light on the end of the run after hitting that room's receptacles. The guys I've been working with like to feed the box for the switch, then 12/2 (or 12/3) to the light, and 12/2 out the bottom to the receptacles. I like my way better because I know which wires in the boxes go where, and I'm not scratching my head wondering which wire on top is for the home run and which is for the light. Plus their way seems more wasteful. The only time I don't go that way is if I'm wiring for a ceiling fan as well. Then a roll of 12/4 would come in handy ...
    Julie in Austin

    Born to brew, forced to work ...

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    Quote Originally Posted by tallgirl
    When I lay out a bedroom, I take the home run to the light, 12/3 from the light to the switch, then exit the switch box out the bottom to the receptacles.
    When I lay out a bedroom, the lighting is #14 jumped from the smoke detector (which is necessarily already in the bedroom and normally very near or over the light switch). The receptacles are a 12-2 home run for each bedroom. As basements and panels in basements are standard fare in my area, the bedroom lighting home run will basically run from the panel to the basement smoke detector; often only 10 or 15 feet away.
    Last edited by mdshunk; 12-11-06 at 02:27 AM.

  8. #8
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    Quote Originally Posted by mdshunk
    When I lay out a bedroom, the lighting is #14 jumped from the smoke detector (which is necessarily already in the bedroom and normally very near or over the light switch). The receptacles are a 12-2 home run for each bedroom. As basements and panels in basements are standard fare in my area, the bedroom lighting home run will basically run from the panel to the basement smoke detector; often only 10 or 15 feet away.
    D'OH! I hadn't thought of that.

    This is what I get for learning how to do this before smokies were a requirement. Somehow I thought smokies had to be on their own circuit with nothing else on them (which is how I do them -- home run to the first, then 12/3 to the rest).

    So ... what else can go on a circuit with a smokie?

    (And I assume we need a "Tips and Techniques" forum one of these days ...)
    Julie in Austin

    Born to brew, forced to work ...

  9. #9
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    Quote Originally Posted by tallgirl
    So ... what else can go on a circuit with a smokie?
    Anything you want, unless there's a jurisdictional requirement or limitation. Seems a waste of a circuit to only have a few milliamps of load with just the smokes. Might as well use that circuit for bedroom lighting, I say to myself. It's already AFCI protected.

  10. #10
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    It's actually a good idea to have the smokes on with something else, such as bedroom lights, so that if that circuit trips, the HO will notice. If it is only smokes, they probably won't notice until the dead battery chirp begins.
    John from Baltimore
    "One Day at a Time"
    Responses based on the 2008 NEC

    If you can stay calm, while all around you is chaos...then you probably haven't completely understood the seriousness of the situation

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