correct wire guage

Discussion in 'Home Theater Projects' started by victor.b, Nov 16, 2005.

  1. victor.b

    victor.b Auditioning

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    Can anyone tell me how to choose the correct guage wire for different wattages. for example, for 1000 watts use 12 guage or bigger? thanks
     
  2. JeremyErwin

    JeremyErwin Producer

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  3. Allan Jayne

    Allan Jayne Cinematographer

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    The thickness (and length) of the wire determines more or less how many amperes the wire can carry. The higher the voltage, the more watts the wire can carry given the same number of amperes. Volts times amperes equals watts, but electrical codes often include a de-rating factor for example 85% which takes into account the fact a motor draws more watts when starting as opposed to normal running.

    But, for supplying power, the quality of the insulation determines how many volts can be carried. For providing the AC power to your home theater this is not a concern with just 120/240 volts. Speaker voltages are even less.

    For household wiring and the typical distances involved, the rule of thumb is, 14 gauge wire for 15 amperes, 12 gauge wire for 20 amperes, and 10 gauge wire for 30 amperes. I don't think the National Electric Code makes a distinction between a small ranch house and a 3 story apartment building with the breaker box in one corner, or whether the wires are screwed (with a better connection) onto outlets in the daisy chain or just pushed in.

    For speaker wiring, impedance translates roughly into a volts/amperes relationship where higher impedance means more volts and fewer amperes.

    Rather than do calculations, electricians and electrical engineers often rely on tables such as the one linked to above.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  4. Brian Osborne

    Brian Osborne Stunt Coordinator

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    Just read through the acticle Jeremy posted.
    Interesting. Looks like the experts say that you could use regular 12/2 romax for my in wall speaker wires and be just as well off as using 12 Gauge strainded monster cable.
    I plan on keeping all my speaker wiring a fair distance from any 120V wiring in the walls.
    My longest run will be about 40 foot and my speakers are 6 ohm.
    I do see a problem with connections though. In my experience, the more times you connect, the more you loose in signal. With that in mind, wouldn't you want to connect direct from amp - romax - speaker. Any reason why you couldn't solder banana plugs on the end of your romax and be golden with that?
     
  5. Chu Gai

    Chu Gai Lead Actor

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    Well there are all sorts of ways to terminate your wires. Bananas is one way. There are types that allow for soldering, others that use screws to secure the wires, and then you've got locking banana connectors. There are also spade connectors. You might find that bananas on the receiver and spades on the speakers gives you more flexibility.
     

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