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Simple residential electrical layout (laugh all you want)

  1. Jun 13, 2012 #1
    You may notice my occupation says "Electrician." Well, you see I am a low volt electrician. My license only lets me work with anything 100VDC or AC so I am very limited. I mostly pull data comm. wire and voice. I have wired in security systems and fire panels as well so I understand parallel and series circuits. Anyways, can someone please explain and show me how a simple electrical layout is wired?

    If you were given me a project, lets take for example a project on a home. You wanted me to wire everything from the electrical panel to the light switches and electrical outlets. I know in most resi homes they have a 240 single phase or dual phase panel? Is that even right? Can you please show me where the white,black, and red wire lands on a switch or explain to me how to wire up a single pole double throw switch, etc?
     
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  3. Jun 13, 2012 #2

    Danger

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    When have you ever seen a red wire in residential housing? :confused:
    Here in Canada (and I believe also in the US), black is hot, white is system neutral, and green is ground. The black wire goes to the gold terminal, the white goes to the silver one, and the ground goes to the green one.
     
  4. Jun 13, 2012 #3

    BobG

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    That part's easy. It's the overall layout that can be hard to understand.

    You would think a single black wire/white wire would go out to each outlet. In fact, I think that's the preferred method, unless you have a switch controlled outlet, in which case each of the two outlets have to be isolated from each other. And so you break the tab between outlets, attach the two black wires (one to each outlet) and the two white wires (one to each outlet) and find out you've disabled every outlet in the room because everything is in series and breaking the tab just broke the circuit!

    And I still haven't figured out what that one mystery switch on the wall actually controls! For a few minutes, I thought I'd solved the mystery - that whoever put in the outlet I replaced failed to isolate the two, which is why the switch did absolutely nothing!
     
  5. Jun 13, 2012 #4
    My point exactly!!!!! Hahaha. See I don't even know what I am talking about!
     
  6. Jun 13, 2012 #5
    I agree. It's the overall layout. My ex gf's mom asked me to help her wire a switch/ receptacle like this one http://www.google.com/imgres?q=rece...=76&start=0&ndsp=22&ved=1t:429,r:10,s:0,i:111

    EDIT: I wasn't quite sure which wires go where...

    In this video where does the second ground attach to on the other end?
    http://www.youtube.com/watch?v=xIL7RKsXQOk&feature=fvwrel
     
  7. Jun 13, 2012 #6

    Danger

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    I've never seen anything like that switch/outlet combination. One of those terminals should be silver rather than both being gold as in the picture. I can only assume that the green one is on the side that's away from the camera.
    I should have specified in my previous post that in normal household wiring the ground conductor is usually bare copper. It's primarily in things like extension cords and appliance wiring that it has green insulation. The terminals, however, are green. In the video, both ground wires wrap around chassis screws in the box, and then go to the green terminal of the outlet. That's just to ensure that the box is grounded even if something goes wrong with the outlet.
     
  8. Jun 13, 2012 #7
    Okay I understand what you are saying. Here is another video of a guy wiring a three way switch.


    In this case there is a red wire, but it's used for "travelers?" The black wire connected to the black screw is power to the light? The light only gets power? I am assuming the light has a ground of its own.
     
    Last edited by a moderator: Sep 25, 2014
  9. Jun 13, 2012 #8
    (Note--red wires are indeed common in US line voltage wiring...)
    Where to start... Residential main breaker panels are (typically) fed by 4 wires from the utility transformer--2 'hots' with 240 VAC between them, a 'neutral' which will give 120 V when paired with either hot, and a 'bond' or ground wire, which is electrically connected to earth ground. The system is often refered to as 'split phase'. The panel system is designed with snap in or screw in breakers, in either single pole, or two pole. These breakers are rated to trip at between 15 amp on up to 200 amp. (A 100-200 amp breaker is typically connected upstream of all other breakers and acts as a main breaker or shutoff for the entire panel.) A single pole breaker ties into one of the hot feed wires through one of two 'buss bars' in the panel, and supplies one hot wire out to the house circuit. A two pole breaker connects to both hot buss bars in the panel, and supplies two hot wires out to a house circuit. There is 240 V between these two wires, or 120 V between either one and the neutral wire. Next--the wire runs to an end point--
     
  10. Jun 13, 2012 #9
  11. Jun 13, 2012 #10
    The wiring that connects the breakers to the end point of use is often called 'Romex', which is a brand name but has become synomymous with this type of wiring. Romex comes with either 3 wires or 4 in a single outer jacket. The 3 wire romex contains a black (hot), a white (neutral), and either a bare or green bond or ground. The 4 wire romex contains these plus a red, which is either used as a second hot in the case of a 240 V circuit, or is used to show a switched hot or some other specialized use in 3-way switching, etc. Romex comes in various wire gauges or thicknesses depending on its use. Thicker wire safely carries more current. Note that the breakers are there to protect the wire, not some appliance at the end of the run. So, the romex wire diameter MUST be properly matched to the size of the breaker used, and vice versa. Typically, 15 amp breakers feed 14 gauge wire, 20 amp feeds 12 gauge, 30 amp feeds 10 gauge, etc. Check with an electrician or the NEC manual... The black or black and red go under the appropriate screw(s) on the breaker. The romex white wire gets screwed into the 'neutral buss', as are all the other neutral wires coming in from various locations. The romex ground gets screwed to the 'ground buss', again as are all the other grounds in the panel. USE GREAT CARE WHEN DOING ANYTHING INSIDE A BREAKER PANEL. A wire slipping out of your hands or brushing up against a buss bar or another breaker can be fatal! I have many years experience and I still get a little knot in my stomach when my fingers are 2 inches away from 240 V/hundreds of amps. A wrong move makes for a really bad day. Next--end point wiring--
     
    Last edited: Jun 13, 2012
  12. Jun 13, 2012 #11
    (Breaker turned off!) To wire a receptacle--An outlet does have push-in or screw in connections for hot, neutral, and ground. There should be 6 inches of romex inside the wall-mounted junction box. The outer jacket is stripped back revealing the 3 inner wires, which then have their ends stripped roughly 1/2 inch to reveal the bare copper. The black goes to the gold screw on the outlet, the white to the silver screw, and the ground goes to the green ground screw on the outlet. If the junction box is metal, there should also be a ground connection made via a screw to the back of the box, which is also connected to the romex ground. Normally a 6 inch piece of ground wire is connected to the box, same with the outlet, and both of these are connected to the romex ground via a wire nut. Everything gets tucked neatly into the box, the outlet screwed in, and the coverplate attached. Note that if other wire runs are also entering the box from other locations, necessary connections, including tying all the ground wires together, must be made. There's no way to detail that here.
    (Basic light switch Rule 1--never ever switch a neutral!) For a simple light switch, I'll assume that the romex from the light is entering the box, as is the supply romex from the panel. First, all the ground wires--the switch, the box if metal, the light feed, and the supply feed--all get tied together with a wire nut and tucked in the box. Next the two white neutrals get stripped and tied together with a wire nut, then tucked in the box. Finally the black supply wire goes to one terminal on the switch, and the black from the light goes to the other terminal on the switch, then this all gets tucked/screwed in, and finally the cover plate is added. Next--a basic 3 way (SPDT) switch--
     
  13. Jun 13, 2012 #12
    There are a number of scenarios for wiring a pair of SPDT switches, depending on where the light and supply power enter the two boxes--I'll cover one. I'll assume the power feed enters one switch box, and the romex to the light exits the other. Normally, a length of romex is run between the two switch box locations, and this romex contains 3 wires plus a ground--black, red, white, and the ground. On the supply side box, the grounds are all tied together as before. The two whites are also tied together. The supply black (hot) is tied to the black colored screw (labeled 'common') on the 3-way switch, and then the black and red wires from the connecting piece of romex are tied, one each, to the two brass screws on the switch--doesn't matter what order although I usually do black above and red below. That box can be closed up.
    At the second switch location, tie all the grounds together with a wire nut and tuck in. Next tie the two white wires together and tuck in the box. Attach the black wire feeding the light to the black common screw on the switch. Finally, tie the last black and red wires from the connecting piece of romex to the two brass screws on the switch, in whatever order you choose--one under each. That box can be closed up. After turning on the power, either switch should turn the light on or off.

    There are a million other things worth knowing, but I hope this overview helps a bit. Please be careful and only do what you are comfortable doing, and NEVER do any wiring of any kind without first turning the breaker OFF. It can be lethal, and often is. I've been doing electrical work for 35 years, and I'm still alive because I respect and understand the dangers of high voltage. Read-read-read, and ask people who know what they're doing before ever attempting anything like what's summarized above.
     
  14. Jun 13, 2012 #13
    Hmmm. IMO, if I've got to ask, it's time to call a licensed electrician. I'll replace fixtures, etc., but running lines... no way. It may violate building code, and in the event of a fire, you may have issues with your insurance, if the fire is in any way tracable to your electrical work. IMO, you're close enough to the requirements, go do the extra time and get the training to round out your current :smile: knowledge.
     
  15. Jun 13, 2012 #14
    Even though I provided the info above as an overview, it was not meant as a comprehensive instruction set, and I would second the comment above 1000%. I was trained by some very knowledgable guys, and there are still things I would not do myself. Unlike wiring up a set of alarm contacts with 22 gauge 12 volt wiring, this stuff will easily kill you or burn down your house. Be smart, be careful, and take no chances with your life/property...
     
  16. Jun 13, 2012 #15

    Danger

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    Okay, yes... red wires are used in 3-way switches. I don't normally think of those as part of the household wiring, since they communicate only between the two switches and have no contact with the rest of the house.

    edit: This was originally a much longer post, in response to #7, but NeuronsAtWork made it totally obsolete. Great posts, NAW.
     
  17. Jun 13, 2012 #16

    BobG

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    They're only showing one side. The other side has the ground and the two silver terminals.

    This is so the outlet can be wired to be controlled by a switch.

    The normal connection is to wire the hot wire to one of the gold terminals and the neutral to one of the silver connections. The plate under the screws is connected to both terminals, so it doesn't matter which screw you use - you're wiring both outlets with one connection.

    Used to be when you wanted an outlet controlled by a switch, you probably had to buy a special outlet. Now it seems that every outlet you buy has the option to be wired together or each outlet wired separately.

    If you want a lamp plugged into one of the outlets to be controlled by a switch while the other outlet operates as normal (always on whenever you plug something into it), you have to break that plate behind the screws so each outlet is isolated and then wire each outlet individually (which is why when I removed the outlet in my house and saw 4 wires, I thought, "Eureka! I found the switched outlet on the first try and it was just wired wrong!" Almost every single outlet in my house has 4 wires, because the outlets are lying directly in the circuit instead of running a diverted wire from the main circuit.

    A few of the outlets have obviously been replaced with newer outlets and whoever replaced them took the time to wire them up the way most outlets are wired nowadays. It just doesn't matter how a house should be wired. Every time you open things up you seem to find something completely different (I'd say something new, but it's usually the older houses that are most confusing).
     
  18. Jun 13, 2012 #17

    Danger

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    Thanks, Bob. While we probably have those things up here, I've never seen one. Any switched outlet that I've ever encountered used a normal wall switch. It just seems really stupid to put them in the same housing. After all, if you have to go to the outlet anyhow, just unplug the damned thing.
     
  19. Jun 14, 2012 #18
    Still, you're probably the guy to ask: when disarming a bomb are you supposed to cut the red wire or the blue wire?
     
  20. Jun 14, 2012 #19
    Neither, cut the blue or red the bomb goes off... You need to cut the brown wire with two continuous white stripes that run along it.
     
  21. Jun 14, 2012 #20
    Thanks! I only had 7 seconds left.
     
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