Dedicated Electrical Outlets?

Discussion in 'Home Theater Projects' started by Bobby C, Aug 29, 2004.

  1. Bobby C

    Bobby C Stunt Coordinator

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    After much delay, I'm starting back into my HT project, so far I've studded out my basement walls and done the low voltage wiring. I now need to do the electric wiring, both for the HT setup and the entire room.

    I'll be running an HT receiver (looks like a Sherwood Newcastle), along with a satelite receiver, & other stuff. My viewing will be provided by a ceiling mounted projector.

    So I was planning on running a dedicated 20 Amp line to the receiver and then distributing the rest of the electronics on another. Does this make sense or should I run a dedicated line to the projector?

    Thanks!
    Bob
     
  2. Leo Kerr

    Leo Kerr Screenwriter

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    In my opinion...

    Put in one 20a circuit wired for the amplifier / signal stack. Put in one 20a circuit for the projector. Maybe run the house-lights on the projector circuit.

    Your amp is the biggest single draw, especially at power-on. In reality, a wild ballpark estimate (based on my own signal-stack) is...

    Amplifier:
     
  3. Wayne A. Pflughaupt

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    There’s really not much chance a receiver will pull 15 amps even at maximum output.

    Technically a single circuit will work fine for such a small installation, but there’s no harm in having a second one if you feel some of the equipment is sensitive voltage fluctuations. If you do use more than one circuit for the electronics, just make sure they’re both on the same phase.

    If any of the lighting is going to be on dimmers, I would not share that circuit with any of the electronics. In fact, I would put in a separate lighting circuit on the opposite phase. Also make sure you use two separate feeds for the opposite-phase circuits and not 12/3 Romex.

    Regards,
    Wayne A. Pflughaupt
     
  4. Bobby C

    Bobby C Stunt Coordinator

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    Guys - thanks for the feedback, sounds good.

    I assume different phase means different sides of the main box, right? I'm not sure what you mean by two separate feeds, Wayne - if I use dimmers (not yet sure what I'll do yet)- but why would I need two feeds? I'll do some studying, I've never dealt with dimmers before.

    Thanks again,
    Bob
     
  5. Wayne A. Pflughaupt

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    Yes, different sides in the main panel.

    Regarding separate feeds, Code allows for 12-3 to be run for two circuits on opposite legs. Since the circuits are out of phase they can share a single common, since with each circuit it would be “vacant” for half a cycle (and then available for the other circuit).

    The problem with dimmers is that many of them generate a lot of hash and noise into the line. If that circuit is sharing the same cable as the dedicated one for your equipment, it will bleed that noise right into the other circuit. A couple of years ago I saw a fellow Forum member trace his system noise problems to this very situation. Suffice it to say, he was hosed – flat out of luck.

    So – don’t use a combined 12-3 cable to feed the lights and equipment circuits. Use a separate 12-2 for each. Even then, it wouldn’t hurt to keep some physical space between them.

    Regards,
    Wayne A. Pflughaupt
     
  6. Leo Kerr

    Leo Kerr Screenwriter

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    Um,

    pardon my ignorance here, but if you really want the electric to be on 'the same phase,' don't you really want to go down the same side of the box, skipping every other one?

    After all, a 120v breaker sits on one leg.

    A 240v breaker sits on two 120s.

    Thus, one could also go down, taking 1 & 5, rather than taking 1 & 3.

    Granted, I do not know the relationship across the bus-bars in the middle... on a single-phase panel, are they on the same leg?

    Leo Kerr
     
  7. Leo Kerr

    Leo Kerr Screenwriter

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    Oh, and Wayne,

    I put in the receiver as less than 15amps. The inrush can be pretty spectacular - my Yamaha makes the UPSs squeak most power-ons...

    ...but again, it's just for that first 1/10th of a second.

    Leo Kerr
     
  8. Wayne A. Pflughaupt

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    Leo,
    Yup, it’s just an instantaneous surge, over and done with before a breaker has time to react – the main breaker at the panel, that is. That’s why I don’t see it as a reason to go overboard in spec’ing power requirements. For that, continual duty, or at least average, is what matters.

    Keep in mind that I’m only coming at this from a code/safety standpoint. Whatever the receiver does with/to a UPS and similar devices, that’s a side issue.

    Regards,
    Wayne A. Pflughaupt
     
  9. Leo Kerr

    Leo Kerr Screenwriter

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    Well, I'll also admit that I frequently turn into someone sufficiently distracted by the trees to notice the forest.

    But I have also been in situations where there is easily the sufficient overhead for routine operation that had a good chance (1 in 3) of breaking when it was powered.

    In my modus operandi, I light up the receiver and then everything else afterword. The projector is on a different circuit. Neither circuit is dedicated for anything... I just don't know if I'd want to have the projector see the amp in-rush voltage sag after it had struck its arc...

    Now, I'll also grant, in our neighborhood, if a neighbor's heat-pump/ac kicks on, all of our lights will flicker (slightly.) Likewise, the close street-lights will also show the momentary sag. If you're really paying attention for it, you can sometimes see a reaction when you turn on a 100w lamp! (But that, fortunately, is relatively rare....)

    It may be that some of my somewhat paranoid recommendations are based on never really having had 'clean' electric.

    Leo Kerr
     
  10. SteveFred

    SteveFred Stunt Coordinator

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    You cant go wrong to have move curciuts if you have the room.

    I put a 60amp subpanel www.stevesreefroom.com/DSCN4167.JPG out of sight near my HT. I really dont think 20a lines are necessary for home theaters(unless codes in your area demands it). I am using a seperate 15a lines to(receiver, projector, lights, sub and one line to the rest of the electronic).

    Now I also know that a dedicated sub panel is not necessary either, but in my case, my 200amp main panel is 45ft away [​IMG]

    Steve
     
  11. Wayne A. Pflughaupt

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    That sounds like some scary power in your neighborhood, Leo. Yikes! [​IMG]

    Certainly that would be a good reason to spec a dedicated circuit for a projector. As much as those things cost I think I’d prefer to error on the side of caution!

    Regards,
    Wayne A. Pflughaupt
     
  12. Leo Kerr

    Leo Kerr Screenwriter

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    well... the neighborhood was really built in the early 1960s... the average house had 50amp service. (I'm not kidding.)

    Since then, we've gone from about twenty five houses on the same feeder to more like a hundred... and many of the houses have added air conditioning and more... a lot of heat-pumps, too.

    And what has the power company done?

    Absolutely nothing. Still the original 1960s service. Oh, the transformers get replaced often enough - one summer one pole-transformer popped off five or six times!

    Yes, it is sort of scary...

    Leo Kerr
     
  13. Bobby C

    Bobby C Stunt Coordinator

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    Thanks for all the replies, guys. A couple of questions:

    1. Is there a way to determine how to determine how a box handles different phases (side by side or same side, skipping)? As it turns out (by coincidence), almost all of my electric devices that have motors are on one side of the panel (refigerator, A/C, fans, etc.). I'd like to keep those on a different phase than my HT equipment.

    2. Wayne mentions that dimmers can cause havoc with electronic equipment, I'll try to get that circuit on a different phase. Even so, are there dimmers that are of a higher quality that create less interference than others? If I go to dimmers, I don't mind spending money on better quality ones - might that make a difference?

    Thanks again!
    Bob
     
  14. SteveFred

    SteveFred Stunt Coordinator

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    Hi bob,

    99% of the time the phases are every other breaker on either side.

    Your best bet if you want to use different phases, is use the 2 breaker spots next to each other, then you are almost for sure will have seperate phases.

    Steve
     
  15. Wayne A. Pflughaupt

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    What Steve said. The confirmation would be taking a voltage measurement across the two hot (black) leads. If you get 220, you did it right.

    Regards,
    Wayne A. Pflughaupt
     
  16. Scott A. Pope

    Scott A. Pope Stunt Coordinator

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    The only thing I read above that I would not do is put room lights on the same circuit as the projector. If you use a dimmer now (or in the future) you are likely to experience som noise in your picture through the projector.

    All of my electronics are on a pure circuit, as well as my computer. I did not place the projector on it's own circuit... this was a mistake.

    Live and learn I suppose.
     
  17. Bobby C

    Bobby C Stunt Coordinator

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    Great info guys, however I want to make sure - I'm a bit dense sometimes[​IMG].

    Let's say I have 8 breakers:
    1
    3
    5
    7
    on the left and
    2
    4
    6
    8
    on the right.

    Same phase would be:
    1 & 5, as well as 4 & 8, right?
    The other phase would be:
    3 & 7, as well as 2 & 6.

    Do I have it right? I'd like to move my breakers to have the heavy motors (A/C, furnace, refirg. etc.) & dimmers on opposite phase as my electronics. It may mean moving some breakers but it sounds like its worth it.

    Thanks,
    Bob
     
  18. Leo Kerr

    Leo Kerr Screenwriter

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    There are a couple of things about this.

    But first, yes, in most panels, your description is generally correct.

    In many cases, it is difficult, if not impossible, to isolate heavy motors that really matter from stuff that you want to have clean power. Many of the 'things that matter' are 240volt machines, and will pollute each pole equally.

    Also, for reasons I don't understand, apart from not wanting to pull one leg down too far, it's generally 'a good thing' to keep the different poles relatively balanced in loads.

    I'm not really quite sure how much isolation really makes sense. From my own (limited) experience, I'd dare speculate that in most situations, the isolation of having the machine in question on a different circuit is sufficient. In cases where that is not sufficient, then the solutions are... extreme. Balanced power, anyone? Power reformers?

    Leo Kerr
     
  19. Bobby C

    Bobby C Stunt Coordinator

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    Of course (smacks head) - 240 would affect both poles/phases. I'll have to re-think my strategy - thanks.
     
  20. Wayne A. Pflughaupt

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    No need to beat your head against a rock over this, Bobby. As Leo correctly noted, mere isolation (dedicated circuits) is usually sufficient. In fact, I’d say almost always. The reason is that any “hash” you get from the motors and stuff will “see” ground before it “sees” your circuits.

    Regards,
    Wayne A. Pflughaupt
     

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