How do I handle the grounded neutral for a simple switch?


I trying to move a switch, which is currently in a 2-gang box. The 2-gang box will need to stay in place (and covered with a plate) as it is also the junction of some other stuff (currently power comes into the box, and feeds the switched light, and 2 branches of outlets). With new codes, I need to have a grounded neutral in the relocated switch. My plan is to do the following:

Note, I have excluded all the other stuff that is in the existing 2-gang box. My question is- what do I do with the neutral in the 1-gang switch box? My existing toggle switches do not have a connection for a neutral (they are not "smart" switches). Do I just cap the neutral line in the single-gang box? Are there new toggle switches that accept a...

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What you will want to do in your case, instead of nutting all the neutrals together (which is technically a 310.10(H) violation!), is keep the neutral from the breaker at B1 and going to B2 and the existing light fixture separate from the neutrals coming in from B4 and going out to the two recessed-light circuits -- in other words, B1 and B5's neutrals are separate. Also, in boxes B4 and B5, keep the neutrals separated from each other as per Tester101's revised illustration -- again, NEC 310.10(H) applies.

One other tip -- the power feed to all the lights should come from the unswitched hot in B3. Otherwise, you wind up having to return the switched hots for the two four-way loops back through B4 and B5 from B3, leaving you without a neutral wire in those cables unless you switched the 14/3 for those runs out for 14/4. Using the netural from the three-way loop isn't an option because it'd create a large, annoying current loop that could interfere with the operation of timer...

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Yes, and yes.

If properly wired (and this is always a potential issue), neutral wires are white. Hot wires are black, red, sometimes blue or other colors except white and green (which is reserved for ground).

Basic switches that have no electronic components simply make or break the hot wire. One side is hot and the other side is switched hot. Modern switches also have a ground, which is green or bare.

More complex switches, such as electronic dimmers, some lighted switches, wifi switches and others also need a neutral.

In the switch you have shown, the two hot contacts are attached to the black wires shown. If your switch has its own wires, the white wire is attached to the existing pair of white wires, and the proper sized wire nut then put back on. A white pigtail (a short length of the same gauge wire) should be connected to the neutral terminal of the switch if it doesn't have its own wire.

The two existing black wires should be attached to...

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TLDR: Seek out 14/4 cable, or run conduit and individual wires. The neutral must be in the same cable or conduit with its partner hots. Neutrals and grounds cannot be borrowed (for your application). Ground cannot be used as a conductor. Or, use a smart remote.

If you're an electronics guy, Code is full of weird idioms that don't make sense until you get deeper into the craft of it.

Neutral is not Ground

It's common in DC electronics to use "ground" as both RF shield and current return.

Code electrical is wired the same as if it were a fully isolated system with equipment ground/shield only as a safety device. To keep voltages from floating/rattling, it is bonded to earth in one location. Only hots or neutral may return current, never ground unless you want a GFCI trip.

Because many people must service a circuit, colors are standardized: Neutrals are always white or gray; grounds are always green, green/yellow or bare. Any loose ground wire (not...

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It sounds like you're trying to replace a 3-way switch with a 2-way switch. If the light has 2 or more switches controlling it, such as one on each end of a hallway or stairway, you'll have to get a 3-way (or possibly a 4-way) switch to replace it. If the switch you're replacing is old, it probably doesn't have a ground. All the new switches have grounds per regulation. If it's not a 3-way switch, you'll have to find out which wire(s) is(are) the ground, which is(are) the neutral or common, which is the hot, and which is the load for the light itself. Sometimes there are more hot wires leading away from the box to supply other lights and such. The wire color doesn't necessarily assure you of a hot wire or a ground wire or whatever. It should, but that's not always the case. If you don't know how to identify each of these, then you really shouldn't be messing with your electrical wiring. I don't want to sound mean...

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Most INSTEON-compatible wall switches and dimmers require a neutral wire connection to operate. While all houses have a neutral wire, the real question is "Do I have neutrals in my switch boxes?"

To answer this question, here are some guidelines:

If your house was built in the mid-1980s or later, there is an excellent chance that you have neutrals everywhere in your home If there is an outlet (wall receptacle) near the switch, most likely that switch box has a neutral Switches that are ganged together have a much higher likelihood of having neutrals, no matter what year

Checking The Switch Box

If you are unsure whether or not you have neutrals, look in your switch box. Please observe all safety precautions before handling the electrical wiring in your switch boxes.

Turn off your breaker box Take off the trim plate over the switch Remove the screws from your switch and pull out the existing switch to look at the wires If you see a white wire (or group of them), it...
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Well I tried searching for a good messagboard on electrical help/handyman and came up with not much. Nothing that could help me here anyway, so I decided to post this here. I know very little about this stuff, but I think I can handle this.

Easy question:

I am trying to replace a regular up/down light switch in my bathroom(house built '66) with a light dimmer switch. I saw a tv show that showed how to do it and it looked soooooo easy, of course they were replacing a brand new switch with a brand new switch.

Problem: the old light switch, when pulled out, has a black wire coming from the back/top and a red wire coming from the back/bottom. That's it-2 wires.

The new one I want to replace it with has a black wire from the back/right side and a black wire from the back/left along with a green wire coming out to, the ground, this much I know.

There is also a double outlet right next to the switch. It has a red and white coming out of it, the red...

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stappy, thanks for the bad news .

Unfortunately ripping drywall isn't an option as my house is completely concrete. Later this afternoon I am going to verify the light fixture and check if the other cables are there as you mentioned. If this correct, theoretically, can I connect a new white(neutral) cable to the existing one on the light fixture and try to get it to the switch box?

I can't use a dimmer because the I am using undimmable CFL's and I can't find a zwave dimmer switch that can support dimmable CFL's. I really don't want to go back to using incandescent light bulbs.
Thanks for your reply

Glad to hear you got it working but I wanted to address your comment above re z-wave dimmer switches that support dimmable CFL's, I have done some testing with Evolve/Linear 3-wire and Leviton and GE 2-wire dimmers and two common brands of dimmable CFL's. I ran the same tests for dimmable LED's with quite different results but have not posted the CFL results. I...

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Thanks for the help guys.

How I found this:
I was attempting to replace a simple 2 position light switch with a motion activated switch. The motion activated switch has to be grounded. It had 4 wires - 2 wires replacing the ones off the existing switch (hot and the line to the light I guess) and 2 wires that had to be connected to ground. There was a bare copper wire in the box, connected to the frame itself, which I'm assuming is ground and what I connected it to.

But the motion switch won't work. Won't work as a simple switch, and no indicator lights on indicating it's even getting power. Its manual seems to indicate that it's not working because it's not connected to ground.

Which is how I found myself plugging multimeter leads into my walls seeing what was grounded or not. (I really should get a 3 prong tester, I know).

On this circuit, I've observed the same 120V/78V/42V issue on three outlets in the hall and neighbouring bedrooms, as...

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once you've identified the hot/neutral wires, wiring the touch switch is a pretty straight forward task. just follow the diagram THAT COMES WITH YOUR SWITCH!. I learned the hard way that not every switch is wired the same. What holds true for one does not hold true for another. I've included wiring diagrams for 3 different switch and the wiring is different for each.

there are 4 wires on the switch. One wire connects to the lamp body (threaded rod). One wire connects to the incoming hot. One goes to the hot from the socket and the other wire connects to the neutral coming in and the socket neutral.

The switch I have, has a maximum rating of 200 watts. This lamp has a single socket rated at 100 watts so this isn't a fine. I don't use anything bigger than 60 watts but you always want to size to cover the maximum amount. Some lamps may use a high wattage halogen or it may have multiple sockets, then you want to...

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Turn off the power feeding the panel you are going to be working in.

It may help to take a few minutes to familiarize yourself with all of the tips in the related wikiHow article on "How to

Master Do It Yourself Electrical Safety

". Shut off all the individual circuit breakers in the panel and then shut off the main switch that supplies power to the panel. This is preferable as it is much safer to operate many smaller current devices, one at a time; than to operate a single, large current device just once. When all the smaller circuit breakers are off, the amount of current flowing through the larger 50, 100 (or more) amp circuit breaker should be zero.


This wikiHow is about wiring a simple electrical circuit.

It doesn't cover the following information, which may vary depending on the type of installation you are doing, and the type of existing wiring you may be connecting to.

Choosing and installing electrical boxes. Selecting and installing...
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Grounding for safety (vs grounding for signal integrity, which is a whole different issue, see below) is primarily a concern for equipment in a metal enclosure. If there is a wiring fault inside the device (frayed wire shorting against the metal inside), then the outer shell of the unit may be electrified. Guess what happens when you touch it? Ouch! By having a ground path, you give the electrical current somewhere else to go (instead of through your body when you touch the device).

You will notice that most devices in a metal enclosure will have a 3-prong input power (if the power plugs in directly without an AC/DC power brick), and also a chassis ground screw.

If you are grounded through the power cord, the middle prong should be connected to the building's wiring and then to an earth grounding rod, assuming your building was properly wired using modern building codes. There are inexpensive testers that can check to make sure your outlet is wired...

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Let's start by looking at how a normal light is wired so that you can understand basic residential wiring for a light switch. The figure below shows the simplest possible configuration:

In this diagram, the black wire is "hot." That is, it carries the 120-volt AC current. The white wire is neutral. (For more information on household AC current and grounding, see How Power Distribution Grids Work.) You can see in the figure that the current runs through the switch. The switch simply opens (off) or closes (on) the connection between the two terminals on the switch. When the switch is on, current flows along the black wire through the switch to the light, and then returns to ground through the white wire to complete the circuit.

The electrician who wires the house normally uses non-metallic sheathed cable, which most people know by the brand name Romex, to run power from the fuse box to the switches and outlets in the house. A piece of this cable is shown here:


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A switch makes or breaks the hot wire, it does not bother the neutral or ground. To wire in a switch just put in between the line and load wires. There are two terminal points on the switch; put the line wire under one and the load wire under the other. For a low-voltage circuit without an obvious hot and neutral, just cut one of the two wires and splice the switch in there. Low voltage stuff should be double-insulated so it really doesn't matter which wire you choose. But be sure to use the right type of switch! If you are using this for low-voltage DC be sure to check the ratings of the switch. Regular switches for household use are for AC only. They can handle 15A, but cannot break an arc that forms breaking a DC load as they are designed to have the voltage across them go to 0V 120 times a second. Most switches will be rated to 600 or so VAC, but only 30-50VDC. Make sure you take this into consideration, or else you will burn your switch's contacts. If you are on...

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Well, yes and no. From what I can tell you NEED a neutral for even the simple on off switch, so YES it will be a problem for people if you don't have a neutral available in your switch box.

For me specifically, at location A I have a simple on/off for the kitchen, and a 3-way dimmer for the dinning room (All in one box). At location B I have a 3-way for the dinning room. Location A has neutral that I think I can tap into, so the simple on/off and the main 3-way are not a problem for me (I think). But at location B I don't have a neutral so I don't think I can put in the aux.

Putting in a completely stand alone z-wave switch/button is a possibility, but there are two potential problems with that for me.

First, this is a dimmer 3-way, so it whatever standalone switch button is there needs to be able to work with the dimmer.

Second, because the wiring is limited here, I suspect that whatever stand alone button/switch I look at getting will have to be...

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Circuit breaker questions

Does a circuit breaker go bad or get weak?
It doesn't start tripping at a lower level than it should, unless a loose connection/contact in/under/at it is making heat that throws it off. There are cases where the handle of the breaker mechanically will not reset, but it is more common that failure to reset is from a short...

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I watched an excellent presentation on the GIL, and how when running in the interpreter only 1 single thread can run at a time. It also seemed that python is not very intelligent about switching between threads.

If i am threading some operation that only runs in the interpreter, and it is not particularly CPU heavy, and I use a thread lock where only 1 thread can run at a time for this relatively short interpreter-bound operation, will that lock actually make anything run slower? as opposed to if the lock were not necessary and all threads could run concurrently.

If all but 1 threads are locked, will the python interpreter know not to context switch?

Edit: by 'making things run slower' I mean if python is context switching to a bunch of locked threads, that will (maybe) be a performance decrease even if the threads don't actually...

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Transfer switches are basically used for switching power from a primary power source to a secondary power source. They are useful in case of sudden power outage, where there is a need to switch to other source. They may be a manual switch, automatic switch, or a combination of both. It becomes necessary to transfer power from a primary source to secondary source in case the incoming power quality deviates from the set limits. A transfer switch is made up of an actuator and a toggle mechanism. An actuator can be activated either manually or automatically, in order to supply energy to the movable contacts on the toggle mechanism. These switches prevent the damage of utility equipment by allowing for operation of the generator without back-feeding to the utility.

The automatic switches are controlled with the help of a programmable logic controller (PLC), a relay logic, or an embedded controller. These circuits monitor the public utility power source constantly for any kind of...

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Please be careful, you need a neutral bond for the GFI outlets to work when you are using the generator as a mobile unit and grounding the generator with a ground rod or building. When you are merging with a building with a grounded system, simply remove the two neutral wires (White) at the generators internal terminals from the generator frame but keep them connected together and terminate connection.

Bonding on a generator questions

Q. If I was to keep the tie between ground and neutral in the generator during standby use, would I have to break the neutral tie coming into home from grid?

A. Never disconnect the neutral line as it enters your house. It is held very well at ground potential. Each transformer is grounded, and every home supplies ground as well. The neutral coming in is the reference to both live lines, and without it, anything connected to either live line could see up to 240VAC depending on what is across the other side. Install a proper...

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By Mike Holt, for EC&M Magazine

Don't let your familiarity with switches interfere with NEC compliance.

We've been around switches all of our lives. We even have them throughout our homes. They are so familiar to us, we can easily think we know all about installing them.

But, the NEC devotes an entire article (404) to switches. Article 100 provides six separate definitions for "switch," covering bypass isolation, general-use, general-use snap, isolating, motor-circuit, and transfer. Article 404 requirements apply to all switches, switching devices, and circuit breakers used as switches.

Some like it hot

You wire a switch to make or break the supply conductor-also called the hot lead. The NEC specifically bars switching the grounded (neutral) conductor or the grounding conductor [404.2(B)] (Figure 404-2).

Note: Graphics are not included in this...

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This neat little device solves three problems that I usually come across when experimenting or doing work around the house or out in the yard:

1) No matter how long your extension cord is, it's always three feet too short. My project adds six feet to any extension cord. If you build one you can make the cord as long as you want. Just remember to derate the power of the appliance accordingly.

2) No matter where your extension cord is, you can never find it. Now I have an extra one in case I can't find my other one or if the other one is in use.

3)Some appliances do not have an on/off switch. I am doing some experimenting with hydronic solar thermal collectors and the pump I'm using does not have an on/off switch. To control the pump I have to plug or unplug it, which is annoying. Other things that usually don't come with switches are soldering irons and hot glue guns.

This project is safe because all materials used are CSA approved, the device is properly...

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Careless troubleshooting of a microwave oven can result in death or worse. Experienced technicians have met their maker as a result of a momentary lapse of judgement while testing an oven with the cover removed. Microwave ovens are without a doubt, the most deadly type of consumer electronic equipment in wide spread use.

The power supplies for even the smallest microwave ovens operate at extremely lethal voltage and current levels. Do not attempt to troubleshoot, repair, or modify such equipment without understanding and following ALL of the relevant safety guidelines for high voltage and/or line connected electrical and electronic systems.

We will not be...

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The first thing you need to do is find out how long of an extension cord you are going to need. Keep in mind that the cord needs to be long enough to reach from whatever outlet you are using, down to the floor beneath your feet, and over to a place that the tool you are plugging into it can reach the outlet. Wiring the box itself should use about 8" of the total length of the extension cord. You'll also want to have some extra length from the plug to the switchbox, so you can reposition the switchbox to be near your foot as you work. I ended up making the first 5ft or so of the extension cord the "plug" side, and only about 1.5ft the "outlet" side.

Once you have found where on the cord you want to put the switch box, mark it with a piece of tape.

The next thing you need to do is determine which of the two wires in the extension cord you need to cut. Most extension cords are "zip cord", they look somewhat like speaker line and have 2 individually insulated wires...

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The mains varying field is minimized by use of a toroidal mains transformer, but the more recent mains powered speakers seem to be coming with *plug top* PSUs, which take the problem further away.

Why Magnetic Fields May Cause the Picture to Rotate

One might think that the result of the Earth's or stray magnetic fields would only be for the picture to shift position slightly. Why isn't this the case?

Magnetic fields don't really 'pull' on charged particles, they result in a force at right angles to the field lines with a direction dependent on the charge (negative for electrons, positive for protons) and field (North or South). The magnitude of the effect also depends on the energy/speed of the particles and their mass. For the case of a CRT:

If the field is horizontal with respect to the screen, the picture will mostly shift up or down. If the field is vertical with respect to the screen, the picture will mostly shift left or right. If the field is in the...
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Warning!!! This project deals with AC electricity which is dangerous if you don’t know how to treat it safely. You must treat electricity with caution. There are many books and websites about electrical safety procedures and if you’re not sure how to be safe you should read that information. The most basic advice I can give is always assume any exposed wires are live and touching them will hurt a lot at best and kill at worst.

Microcontrollers are good at controlling small devices, but frequently we DIY-ers want to use them to control things that aren’t so micro. In this post I’ll talk about how to turn on household lights with the Arduino microcontroller. Actually this technique isn’t limited to lights, it works for anything that gets plugged into the wall like a table saw or a small rail gun.

The first thing you need is a cheap extension core that you are willing to cut in half. After cutting and stripping the wires you need to solder in a relay. A relay is...

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