I have a question about what to do with ground wires. I am installing a new light fixture above my dining room table.  Fixture comes with a ground wire obviously.  Main electrical wiring has the normal black and white wire AND a bare copper wire (which I’m assuming is another ground wire). In addition it appears that my octagonal electric junction box also has a green copper ground wire attached to box with a screw, so I now have three grounding wires. Light fixture mounting bracket has the normal green screw that I should be attaching a ground wire. Question: Is which wire do I attach to the mounting bracket ground screw AND what to do with the other grounding wires??
123208
I am replacing a light fixture in my bathroom and have the following setup:   The electrical box is plastic The wire coming from supply has black (hot), white (neutral) and copper (ground). The light fixture comes with a metal bracket for attaching to the electrical box that has a green screw The light fixture has black, white and copper wires.   The instructions supplied with the fixture dont give me an example of how to wire it up if there is an existing ground wire coming from supply.  It only tells me to attach the copper wire of the light fixture to the green screw.  So I'm curious what I should do with the ground from the supply.  Looking online, my options appear to be this:    So I think since the electrical box is plastic, I should just connect the ground of the supply with the ground of the light fixture with the wire nut.  Do I need to connect both of them together with the green grounding screw on the light fixture as well, or would that only be if the electrical box was metal?
86676
I am a software developer trying to understand how computers work at a lower level.  I have managed to create a few simple circuits, one which lights up an LED.  I have noticed that all the instructions advise you to connect the components in a certain way.  Please have a look at the circuit .  The LED is connected to column E and column F.  Why can't you just connect the LED to G7 and H7 and the black cable to F7? Why does the LED plug in across the gap?  I seem to remember something about this from school.  I have checked my GCSE textbook and also two textbooks which I am working through.  I have also Googled it but I cannot find an answer and hence the reason for this very basic question.
67389
So, I've put in or replaced several outlets following wiring instructions online and in the box. Nothing big. I know that if I fail to turn off the breaker then I shouldn't directly touch the black wire, but touching the white wire or the bare copper wire is fine.   From this, I know that the black wire is the supply, power is flowing from it, and will happily flow into me. Since neither the white wire nor the bare copper wire shock me, I don't know the difference between the two, other than "Power flows into these once a circuit is completed" So what is the difference, in detail, between the neutral and the ground connectors in 110V applications?
49071
So I'm trying to power 2 of these  together in series. I know that I have to add the voltage of the two lights together and get a resistor that restricts the power to that level. I have a 9V battery and the lights are 3V each. I brand new to all of this, and understand almost nothing, so any help would be appreciated. Can someone help me choose the correct resistor (And how to identify that resistor with the color branding thing) so two of those lights listed above can be wired in series? Thanks!
54888
I'm having trouble understanding why the earth is a viable fault path for electricity brought into my home. Isn't there really high resistance? I mean, it's dirt?   Also, let's say I connect the hot wire coming into my house directly to the ground wire. What is the path that the electricity takes to get back and "complete the circuit?"
46194
I'm replacing a light fixture, but upon removing the old light I discovered the wires are not in a box. Can I just anchor the mounting plate to the drywall or is a box mandatory?
34459
Can a single ground wire ground 2 outlets? I don't want to run another wire through the wall, if I can run a wire to that other ground wire (and have 2 outlets being grounded by one wire).  In other words,     I also have concerns about equipment protection.  Will adding a ground wire be worse for my electronic equipment in any way?   If I am having problems with equipment taking damage, will this help?
50505
I am looking at replacing a couple of old, porcelain style single bulb fixtures in my basement with some 4 lamp fluorescent fixtures.  I am actually running new wire to the fluorescent fixtures from a 100amp sub panel in the basement, and not reusing then existing wiring that goes to the current light.  As I was taking the porcelain fixture down I discovered that there is 14 gauge wire going to it - ok.  There are 3 such fixtures in the basement.  There are also other things on this same breaker upstairs in the main living part of the house - 3 or 4 outlets that are on 12 gauge wire.  The breaker is a 20 amp breaker for all of these.  Is this ok to mix 14 &amp; gauge wire like this?  If not, why did they do it?
29228
I'm replacing a ceiling fan and it has three wires as is common: black, white, and bare ground. I have a two-toggle wall switch. One switch makes the black wire hot (for the motor), and the other switch makes the white wire hot (for the integrated light). So it looks as if the white wire in the ceiling is used as a hot for the light rather than a neutral wire as is common.   From the main power, there are three wires:  Black wire has nut that is spliced to both the Dual Switch (that controls the ceiling fan) and the other switch which operates the upsidedown wall outlet.  White Wire is spliced to just the upsidedown wall outlet. (no connection to Ceiling Fan)  All three bare ground wires are connected together.  So the Dual switch that controls the ceiling fan has The Black Wire from the main power to the top of the switch, The other top wire at the ceiling fan Dual switch is the BLack wire that runs to the Ceiling Fan (assuming to run the fan light, and the Bottom wire is the White wire which appears to operate with the bottom switch (of the dual switch) when it is turned assumed for the fan motor.          Crazy thing is this is how the home builder (Beezer Homes) wired the home when new in 95). I remember the builder was originally suppose to install 3-toggle switches in two bedrooms.  They only installed 2-toggle switches.  They corrected the problem by install the dual switch in place of one of the single toggle switches.  The fan was wired with the House bare ground wire being utilized as the Fan's neutral White Wire (and that being connected to the mount ground wire. The houses Neutral is the hot wire for the fan motor. Black wires are connected as normal and for power to the fan's light.
12969
I'm a bit confused about the concept of ground, and perhaps voltage as well, particularly when trying to analyze a circuit. When I learned about Ohm's law in grade school, I learned how to apply the law to calculate current, voltage, and resistance of simple circuits.   For instance, if we were given the following circuit:    We would be could be asked to calculate the current passing through the circuit. At the time, I'd simply compute (based on the rules given) 1.5V/1Ohms=1.5A.  Later on, however, I learned that the reason the voltage of the resistor would be 1.5V is because voltage is really the difference in potential between two points, and that the difference of the voltage across the battery would be the same as that of the resistor (correct me if I'm mistaken), or 1.5V. I got confused, however, after the introduction of the concept of ground.   The first time I tried to do the current calculation for a circuit similar to the previous circuit on a simulator, the program complained about not having a ground and "floating voltage sources". After a bit of searching, I learned that circuits need ground as a reference point or for safety reasons. It was mentioned in one explanation that one can pick any node for ground, although it's customary to design circuits so there is a "easy place" to pick ground.   Thus for this circuit    I picked ground at the bottom, but would it be okay to pick ground between the 7 ohm and 2 ohm resistor - or any other place? And what would be the difference when analyzing the circuit?  I've read that there are 3 typical ground symbols with different meanings - chassis ground, earth ground, and signal ground. A lot of circuits I've seen used in exercises either use earth ground or signal ground. What purpose is there in using earth ground? What is the signal ground connected to?  Another question: since the ground is at unknown potential, wouldn't there be current flowing to or from ground to the circuit? From what I've read we treat the ground as 0V, but wouldn't there be some sort of effect because of a difference in potential of the circuit and ground? Would the effect be different depending on what ground was used?  Finally: In nodal analysis, one customarily picks a ground at the negative terminal of the battery. However, when there are multiple voltage sources, some of them are "floating". What meaning does the voltage of a floating voltage source have?
91944
I asked this question in a convoluted way and didn't get any answers, so I thought I'd ask again and make my question clearer with more images.  I have a 150 amp disconnect at the meter. The box only has the 150 amp disconnect with no additional room (see picture). The 150 amp sub panel inside the house is full.  I'd like to upgrade that box with 200 amp service and some room for additional breakers.  Can I install a 200 amp box like the image below, then add a 150 amp breaker (also pictured) for the 150 sub panel in the house, leaving me with additional space for more breakers?  @Tester101: to answer some of your questions and address your points: 1) The overhead conductors that run from the pole to the meter are adequately sized for 200 amp service 2) The meter and the disconnect are in the same box (as shown), so the issue of adequately sized conductors between the meter and disconnect is minor 3) The grounding/bonding conductors may have to be upgraded, but I'll consult an electrician for that (and all of the issues you've mentioned...I had not planned on proceeding without having a pro review my plans). I really just wanted to make sure I was on the right track re: replacing the meter/disconnect box with a larger disconnect (200 amps), then have a 150 amp breaker for the main subpanel already located in the house. I would then have additional room in the new meter/disconnect box to add circuits as needed
62051
I just replaced a broken light fixture in my closet. (The switch in the light fixture broke when I pulled too hard on the chain.)   When replacing the light fixture I noticed that there is only 30 V AC between the white and black wires. The ground wire is cut back and is not being used. By the way, the wiring in my house is all aluminum.   I know the new light fixture works. I checked it out with my multimeter, and I tried it in a different closet. But the light bulb won't turn on because there is only 30 V. (Even if I disconnect the light fixture completely there is still only 30 V.   It seems to me that it must be a problem with the wiring.  My attic does provide some (difficult) access to the wiring, but I am not sure where to start looking for the problem or what to look for. Can anyone offer some suggestions?
80731
I accidentally pulled 6-4 wiring to a machine that only needs 240 and no neutral. What to do with the white wire?  I read  that at the machine, I just cap the white wire.  When I go to connect the wires in the main breaker panel, do I still connect the white wire to the neutral bus, or do I cap it in the panel as well?
70538
In my kitchen, I want to replace a regular 120V receptacle with a GFCI-protected receptacle. The instructions describe what to do with a regular 2-wire + ground feed, with and without daisy chaining to other receptacles, but not how to do it with a 3-wire + ground feed. Please describe how I should connect the new receptacle.  Here's a diagram of how the non-GFCI receptacle is currently wired, in my best 6-year-old artistry:   I think it's connected this way so that each receptacle in the kitchen has their two sockets supplied by different breakers. At the service panel the circuit is controlled by a joined pair of 15A breakers. I assume the white and black are separate 15A lines and the red is a common neutral (?).  Here are the instructions for connecting in a 2-wire scenario.    How do I connect this? Or should I consult an electrician?  EDIT  From
60431
I am installing a drop ceiling with pot lights as part of remodeling a portion of my basement. Since I am refinishing the entire room (newly framed walls), it seems like I have a catch 22:   I need to get the electrical rough-in done before I put up drywall (including the wiring to the pot lighting fixtures in the drop-ceiling) However, I have always seen drop ceilings installed after the drywall is up, which means I cannot mount the pot lights in the ceiling/wire for them unless I mount the grid (or some portion of it) for the drop ceiling first.   Can I wire up a portion of the grid for the suspended ceiling before drywalling and leave gaps around the edges slightly bigger (~1/8" - e.g. 3/4" gap for 5/8" cement board) than required to insert drywall, or is this a ludicrous suggestion?  Or, is the wiring for pot lights in this situation typically addressed as part of the final inspection? I was not planning on having any additional junction boxes between the panel and the pot lights (all splices to supply multiple lights are supposed to just be inside of the boxes on the pot lights per my submitted plans). Since a portion of the wire run from the breaker panel to the pot lights will be concealed by dry wall for another room (I am finishing the other room at the same time under the same permit) which means the cable would be run from the panel and dangling near where the pot light will eventually be mounted for the rough-in inspection in this case.  I plan on calling my inspector to see what is acceptable, but what is typical practice in this situation?
96043
I probably have this diagram for my project. Or problem.  Facts:   a) only 2 wires out of wall, B &amp; W;  b) switch ON, lights ON  Ceiling electrical box:   One black and one white connects to the ceiling light fixture.     Project: I need to add a combo switch/outlet  UPDATE after suggestions  Grey= Neutral Is this right? If it is, it seems to me receptacle will be ON at all times, right?
24261
I recently purchased an older home and wanted to install GFCI outlets in the kitchen.  When I opened up the outlet, there were four wires (two black and two white) in addition to the ground.  I watched a few videos online about installing GFCI outlets, but they only gave guidance about doing it when there's one black, one white and the ground. Currently, the two-prong outlets have all four wires attached - the two black wrapped around screws on one side and the two white wrapped around screws on the other side. What do I do with these "extra" black and white wires on the GFCI outlets?  Attach them somehow or tie them off?