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Thread: Seperated Lighting and Plug Circuits

  1. #1

    Default Seperated Lighting and Plug Circuits

    Hey guys,

    So I read the posts about not needing to seperate the light and plug circuits and I'm a bit confused. When I'm in someone's house and they plug in a device and the lights dim. Isn't that due to the lights and plugs being on the same circuit?

    I've always seperated my lights and plugs because of this. Is there another reason the lights are dimming?

    Tom

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    Old, undersized, or less than perfect connections, or underpowered main could do it too. At the cost of copper, I can see the reluctance of avoiding separate lines for the hard-wired lighting, but personally, I still prefer it. In a room without hard-wired lighting, it doesn't make a difference, since you'd likely be using plug-in lamps.
    Jim DeBruycker
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    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    Electrical Contractor/Instructor jwelectric's Avatar
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    To install lights and receptacles (plugs) on separate circuits is a design issue and will have little or no effect on the dimming of the lights when a large draw appliance comes on.

    It takes 6.25 times 10 carried to the 18th power of valance electrons to equal one coulomb. One coulomb for one second equals one amp.
    If I have an appliance that draws 10 amps come on then it is going to need a whole bunch of these electrons when it starts and will jerk some of them from other things that is already on.

    This draw of electrons away from a light bulb is noticeable to the eye therefore some people think that something bad has happened and get scared.

    What scares me is driving down the road in the mornings. Just this morning I was in a 45 MPH speed zone behind a school bus when here comes a pick-up with a ladder rack stacked four ladders deep on both sides and a sign on the doors that read, “We Fix Anything INC” running around 65 MPH.
    Now it wasn’t the speed that scared me so bad but the fact that the unshaven man driving the squatted in the back pick-up was holding a cup of coffee in one hand and talking on a cell phone with the other. I suppose he could fix everything except himself.

    Now I am sure that you are going to get all kinds of answers as to why the lights dim ranging from the type of wire nut used all the way to the name of you power company.
    The truth of the matter is that there is a voltage drop across the entire system any time a high draw appliance is started especially if it is a motor or inductance draw.

    There is more danger in getting into you car and driving to the store than there is in the dimming of the lights.

    Now it is your money that is being spent so I suppose it would be up to you to install the circuits the way you desire.
    The one thing I can say with 40 years of experience is all this talk about being in the dark if a breaker trips and the dimming of lights is nothing more that talk.

  4. #4

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    I've never considered it a safetly hazard. Just an annoyance. My interpertation of lights dimming is cheap and bad installation. Regardless if this is true or not that is my interpertation.

    Every house I've wired has the lights and plugs seperately. I've never had lights dimming. Not once. However my friends (2) that have houses built within the last 8 years or so that have wiring that connects lights and plugs. They have dimming issues.

    Like I said just appears to be a poor set up to me when the lights dim regardless of what causes it.

    I'm willing to admit that maybe it isn't the lights and plugs on the same circuit but I'd like to hear some other opinions.

    Tom

  5. #5
    DIY Senior Member BrianJohn's Avatar
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    Flicker is a byproduct (as stated) of loads coming on line, as little as 3 Volts drop can result in noticeable flicker, In my experience some people (MAINLY WOMEN) are more likely to notice flicker or maybe not tolerate flicker.

    3 volts drop (VD) is nothing when a compressor is starting, utilities typically use smaller conductors than contractors are required to utilize, for a variety of factors, that coupled with minimally sized transformers (transformers that are sized to carry maximum load are more efficient) and the VD can reach or exceed 3 Volts easily in the best of homes.

  6. #6
    Licensed Electrical Contractor Speedy Petey's Avatar
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    Quote Originally Posted by statjunk
    My interpertation of lights dimming is cheap and bad installation. Regardless if this is true or not that is my interpertation.
    This is absolutely NOT true!

    I have seen this in new, old, lighting and receptacles separated or not.
    It has more to do with what's outside the home than how it is wired inside.

  7. #7
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by statjunk
    Every house I've wired has the lights and plugs seperately. I've never had lights dimming. Not once. Tom
    So you have wired a total of one house and they haven't turned on the power yet.

    Yes I can see why you are thinking the way you are.

  8. #8
    DIY Senior Member BrianJohn's Avatar
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    Every house I've wired has the lights and plugs separately. I've never had lights dimming. Not once. Tom
    I do not wire houses I work as a testing and power quality/grounding expert. My rates are fairly steep, so home owners rarely hire me....BUT, I have done quite a few residential FLICKER studies (mostly large big buck homes) wire a house with number 8 AWG, separate the circuits lighting and outlets (which I did in my house) and flicker can still be an issue. There is more too it than just the branch circuit wiring.

    And that's the way it is.

  9. #9

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    Quote Originally Posted by jwelectric View Post
    So you have wired a total of one house and they haven't turned on the power yet.

    Yes I can see why you are thinking the way you are.
    Why would you say something like this?

    Grow up.

    Tom

  10. #10

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    Quote Originally Posted by BrianJohn View Post
    I do not wire houses I work as a testing and power quality/grounding expert. My rates are fairly steep, so home owners rarely hire me....BUT, I have done quite a few residential FLICKER studies (mostly large big buck homes) wire a house with number 8 AWG, separate the circuits lighting and outlets (which I did in my house) and flicker can still be an issue. There is more too it than just the branch circuit wiring.

    And that's the way it is.
    That's kind of what I was looking for. Thanks for the info.

    Since I wire my plugs in 12 and lights in 14 I'll continue to keep them seperated but it's good to know.

    Thanks

    Tom

  11. #11
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by statjunk View Post
    Quote Originally Posted by jwelectric View Post
    So you have wired a total of one house and they haven't turned on the power yet.

    Yes I can see why you are thinking the way you are.
    Why would you say something like this?

    Grow up.

    Tom
    Because you made this statement and expected the rest of us to believe that you have mastered electron flow from some kind of silly wife’s tale of keeping the receptacles and lighting circuits separate.

    Quote Originally Posted by statjunk View Post
    I've never had lights dimming. Not once. Tom
    Now if that statement was not enough to bring forth some type of remark we can add the opening question that you asked into the discussion;
    Quote Originally Posted by statjunk View Post
    Hey guys,
    I've always seperated my lights and plugs because of this. Is there another reason the lights are dimming?

    Tom
    First you ask why the lights dim and then come back and let everyone know that you have the solution to the problem.
    How can you have the solution if you don’t know the cause?

  12. #12

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    I never claimed to have a solution. Re-read my posts. Secondly, none of the houses I've wired have had lights that dim. That is a statement of fact.

    Your stating in a condesending way that I've only wired one house, is your mindless running off at the mouth.

    Your obviously very knowledgeable in electrics. I'd stick to that. In the meantime work on your communication skills.

    This thread was started as a discussion topic. I wanted to see others experience with this in testing these theories and what not. That is all. BrianJohn provided exactly what I was looking for.

    Tom

  13. #13
    Electrical Contractor/Instructor jwelectric's Avatar
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    Quote Originally Posted by statjunk View Post
    I never claimed to have a solution. Re-read my posts. Secondly, none of the houses I've wired have had lights that dim. That is a statement of fact.
    Well I must be misunderstanding you original question then. You said in the original post;
    Quote Originally Posted by statjunk View Post
    Hey guys,

    So I read the posts about not needing to seperate the light and plug circuits and I'm a bit confused. When I'm in someone's house and they plug in a device and the lights dim. Isn't that due to the lights and plugs being on the same circuit?

    I've always seperated my lights and plugs because of this.

    Is there another reason the lights are dimming?

    Tom

    Quote Originally Posted by statjunk View Post
    Your stating in a condesending way that I've only wired one house, is your mindless running off at the mouth.
    No I just put two and two together and came to a conclusion.
    Quote Originally Posted by statjunk View Post
    Every house I've wired has the lights and plugs seperately. I've never had lights dimming. Not once. Tom
    In order for this to be true it would mean that you have only wired one house and the power has not yet been turned on.

    Quote Originally Posted by statjunk View Post
    Your obviously very knowledgeable in electrics. I'd stick to that. In the meantime work on your communication skills.
    Thank you for the complement. I do need some help in communication as I have a problem speaking some of the different languages of the students in my classes.

    Quote Originally Posted by statjunk View Post
    This thread was started as a discussion topic. I wanted to see others experience with this in testing these theories and what not. That is all. BrianJohn provided exactly what I was looking for.

    Tom
    Brian didn’t say anything different than any of the other had to say. He even shot down your belief in separate circuits cures the problem.
    Quote Originally Posted by BrianJohn View Post
    I wire a house with number 8 AWG, separate the circuits lighting and outlets (which I did in my house) and flicker can still be an issue. There is more too it than just the branch circuit wiring.

    And that's the way it is.
    Unless you can control the power from the point of generation to the point of use there is no way to control the dimming of lights when a high draw appliance or even a switch from one power grid to another occurs.

    Having worked in the field for almost 40 years and standing in a classroom for the last 7 years the one thing I do know, incandescent lights will flicker when there is the slightest difference in voltage drop no matter how they are wired. They can be on separate panels and they will still flicker.

    If you want to get real technical incandescent lights turn on and off at least 60 times a second as the sine wave changes from positive to negative.

  14. #14
    Retired Defense Industry Engineer jadnashua's Avatar
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    Well, if you really want to get technical, the filaments don't stop glowing as the a/c transits zero, they take too long to cool off. They do dim, or oscillate their level. Now, a florescent does generally turn off.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  15. #15
    Electrician frenchelectrican's Avatar
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    Quote Originally Posted by jadnashua View Post
    Well, if you really want to get technical, the filaments don't stop glowing as the a/c transits zero, they take too long to cool off. They do dim, or oscillate their level. Now, a florescent does generally turn off.
    sure sure ,, if you really want a really annony flickering on indscent lamps why not run this on the 25 HZ supply then you will get the idea why

    but if you want almost complety flicker free run either in DC or go with 400 HZ or higher with good power supply unit.

    Merci, Marc

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