Re: Why the neutral in USA wiring?

From: John Popelish (jpopelish_at_rica.net)
Date: 03/29/05

  • Next message: eeh: "Data/Address line Matching" 
    Date: Mon, 28 Mar 2005 22:24:05 -0500

    Eric R Snow wrote:
    >
    > I was showing a guy how to wire a lamp and explained how only one wire
    > was switched, and that wire was the hot. The neutral just ran straight
    > to the switch. He asked me why a neutral was used and I replied it was
    > probably something which the power company did for their own reasons.
    > Since 230 volts is used on appliances with only a ground and no
    > neutral (unless 115 volts is used in the same appliance) I'm wondering
    > if my answer was correct. If the neutral is used because of the power
    > companies what would their reasons be? I hope to find the answer soon
    > so I can tell the guy the real reasons.
    > Thanks,
    > Eric R Snow

    Power is supplied to residences in the US as 240 volts center tapped.
    If an appliance needs a high power level (range, water heater, heat
    pump) is gets the full 240 volts and both lines are switched to turn
    it off. The two lines swing in opposite directions around the center
    tap (picture an electrical see saw, with the seats being the lines and
    the center tap being the central pivot. The center tap voltage is
    grounded at the pole, and at the service entrance (fuse or breaker
    box) to minimize the peak voltage on any line with respect to ground.
    The grounded center tap is called the neutraled conductor or the
    neutral.

    Receptacles that supply lower power appliances and lighting circuits
    use only half of the supply (one line and the neutral) to feed half of
    the 240 volts or 120. Since the neutral conductor is at or near
    ground potential (except for the voltage drop along the neutral
    wiring, back to the ground point) there is little safety or functional
    reason to break it with a power switch. Breaking the single hot line
    turns the circuit off, while keeping the load near ground potential. 

    -- 
John Popelish
  • Next message: eeh: "Data/Address line Matching"

    Relevant Pages

    • Re: Really stumped: PS inoperative
      ... When the front panel switch is depressed, the voltage drops to ... The grey PWR_OK wire on the main power connector reads zero after the PS ...
      (comp.sys.ibm.pc.hardware.misc)
    • Re: What can I replace this latching relay system with?
      ... Retrofitting a modern AC switch box if necessary would be ... The power wire is daisy chained. ... remote rotary controller. ...
      (comp.home.automation)
    • Re: Should I PID my Heat Exchanger?
      ... how did you bring power into the PID (a separate line ... I stole the power off the rotary power switch which is ... 16 gauge unstranded copper wire for the power to the controller and the ...
      (alt.coffee)
    • Re: Electrical Switch Question
      ... On a "normal" Leviton 15 amp switch there are "secondary" attachments for power on the back via a "push in port". ... So the line side has both screw terminals and this additional port (I presume to do what I want to do - bring one power line feed into a box to power 3 separately switched circuits). ... The problem is that the push in port only accepts 14 gauge wire and I have 12 gauge wire as this is a 20 amp circuit. ...
      (alt.home.repair)
    • Re: Installing dimmer switch in old house
      ...  One wire connected to the top of lightwitch ... without having to make an electical connection. ... Switch off the light. ... Disconnect the power at you main breaker / or remove the main fuse ...
      (alt.home.repair)