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    Question about Noise and Domestic Wiring to Outlets

    Hi all,

    I have a question about home wiring.

    1) Are normal homes wired with 120(L-N), 120(L-G), 0(N-G)?
    2) In what situations are homes wired with 120(L-N), 60(L-G), 60(N-G)?
    3) Would the situation in #2 present any unique situations in regards to noise or signal quality?

    Thanks!

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    Re: Question about Noise and Domestic Wiring to Outlets

    Quote Originally Posted by elektrotechnik View Post
    Hi all,

    I have a question about home wiring.

    1) Are normal homes wired with 120(L-N), 120(L-G), 0(N-G)?
    2) In what situations are homes wired with 120(L-N), 60(L-G), 60(N-G)?
    3) Would the situation in #2 present any unique situations in regards to noise or signal quality?

    Thanks!
    No home is wired that way if the electrician/engineer/inspector are doing their jobs.



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    Re: Question about Noise and Domestic Wiring to Outlets

    Quote Originally Posted by wade_hassler View Post
    No home is wired that way if the electrician/engineer/inspector are doing their jobs.
    Wired in the way of bullet #2, or in bullet #1?

    Can you comment on whether bullet #2 wiring would present any unique signals and/or noise?



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    Re: Question about Noise and Domestic Wiring to Outlets

    #2 is sometimes seen in recording studios and such where the somewhat dubious claim is that it reduces capacitively coupled noise.

    It poses some unique circuit protection challenges (Double pole breakers and fusing for fire protection), disconnect time and loop impedance being the biggies, and must be treated as a separately derived supply (I think there is something in the NEC on the subject, but this stuff is really the proper domain of the electrical engineer rather then electrician)..

    Interestingly most US homes are fed this way anyway, it is hust that the voltage is 240 presented as 120-0-120.

    Regards, Dan.



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    Re: Question about Noise and Domestic Wiring to Outlets

    THe Distribution transformer uses one centre-tapped phase to supply 240Vac in North America called Line 1, Line 2 and tap is Neutral.

    Thus outlets are all L1+N or L2+N with safety ground.
    Thus every 2nd breaker taps L1 or L2 and goes throughout the home. Electric Stoves get L1+L2 for main oven heaters and only use L+ N for stove top to eliminate need for double pole relays, fuses etc.

    Although L1 is 180 deg out of phase with L2, they are still called Single Phase as it is derived from 1 of 3 phases with a centre tap out.
    A good design question lists your overall requirements™ The best question deserves a better answer. ™
    ... Tony Stewart EE since 1975



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