FAQ: Neutral and Ground Wires are not Interchangeable

wiring

#1

Continuing the discussion from Current Device Deals & Best Prices:

They are both wires, but they serve very different purposes in a residential home circuit. One is grounded and one is grounding.

If most of your experience has been with battery operated devices, or in a physics lab, you are generally working with direct-current, and,the ground and the neutral may well work in a very similar way. In these environments you do sometimes hear the statement that the ground and neutral are interchangeable.

However, in a house, the ground will often be connected to a metal appliance such as a washing machine or a toaster, and normally carries very little current. Its purpose is to be used when there is a fault in the normal live circuit so that the extra current has someplace to go.

The neutral will be the return half of the live AC circuit.

So even though they are both wires, they typically function very differently.

Rerouting the ground into the live circuit runs the risk of both removing the grounding function and possibly pumping live current to that metal appliance. All depending on the exact wiring in that specific home, of course.

See the following:

In the US, electrical code requires following manufacturer instructions. If the manufacture instructions call for four wires, then trying to get by with three is an intentional code violation. Not something to be undertaken lightly.

If the manufacturer instructions say that a neutral should be connected to a specific switch input, connecting a ground there again is an intentional code violation.

For more information on wiring network switches, see the wiring FAQ:

It can help to remember that our goal is not to power on a single individual switch, but rather to power on the switch while also maintaining the fire safety and electrical safety integrity of the whole house wiring system.

Submitted with respect.


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(Colin) #2

Are you familiar with what a home-run circuit is? If a circuit is home-run, it’s directly going back to the circuit breaker box, not tied into anything else. So in this circuit you have the potential for a hot, neutral and ground. the hot goes from the load (outlet, in this instance) to the breaker. the Neutral goes from the neutral side of the load to the neutral/ground bus bar in the circuit breaker. The ground… goes back to the neutral/ground bus bar in the circuit breaker. So there are two identical wires going from the oulet to the bus bar in the box. Any grounding happens between the bus bar and the ground wire/ground stake, not between the ground wire and the bus bar.


#3

Sure, but this whole conversation started when someone who knew very little about wiring made the blanket suggestion that anyone who didn’t have a neutral at their switchbox could just stick the ground in there instead.

I know your point is that people shouldn’t be doing wiring unless they know exactly what they’re doing, and I agree completely, but they don’t always know that they don’t know.

Especially when they think they’re just replacing one switch with another. Not realizing that the wiring for a networked switch may be quite different then the non-networked switch that they are replacing.

Many of these people have no idea where the ground runs to. Or what difference it might make. This is one reason that the NEC says follow the manufacturer’s directions. It just keeps things simple or no matter what level of knowledge or experience you have.

My uncle always used to say “the hardest thing to remember is what you didn’t used to know.” People who don’t know wiring will be better served by the rule of thumb that the ground and the neutral are not interchangeable. People who do know wiring, will know what to do to figure out what is going on on the circuits in front of them. :sunglasses:


(Colin) #4

Alas, the world is full of people that think they know what they don’t, isn’t it? I see it all day long in IT too. :fearful:


(Jason "The Enabler" as deemed so by @Smart) #5

Copy and Pasted from the other thread to keep things neat.

Maybe this will help clear some things up…
Please take note of the BOLD parts of this.
You are playing with at least 120 VAC. This electricity will take you from walkin and talkin to a lump of coal really quick. Now, if you want to play with your own life, no one can stop you. But what about when one of your kids is screwing with something. How are you going to feel when you have to live the rest of your life knowing your violation of a safety hazard ended one of their lives.

Stepping down from my Father of 8 soapbox

Hot: The black wire is the hot wire, which provides a 120 VAC current source.

Neutral: The white wire is called the neutral wire. It provides the return path for the current provided by the hot wire. The neutral wire is connected to an earth ground.

Ground: The bare wire is called the ground wire. Like the neutral wire, the ground wire is also connected to an earth ground. However, the neutral and ground wires serve two distinct purposes.

The neutral wire forms a part of the live circuit along with the hot wire. In contrast, the ground wire is connected to any metal parts in an appliance such as a microwave oven or coffee pot. This is a safety feature, in case the hot or neutral wires somehow come in contact with metal parts.

Connecting the metal parts to earth ground eliminates the shock hazard in the event of a short circuit.

Note that some circuits require a fourth conductor. When a fourth conductor is used, it’s covered with red insulation and is also a hot wire.


(Doug) #6

Just as an FYI, I installed the Dragon WS-100 today and it looks almost identical to the GE in many ways. It certainly looks like the same “base” manufacturing to my eyes. Same rear housing, same exact terminal connections, etc. It went in exactly like the GE (which I also have installed) and paired correctly on the first try. The blue light on the GE is white on the Dragon. I put in a 3-way with the dragon auxiliary. Fingers crossed. I have one more to install this week.

Also, for those without neutral connections in older construction (neutral bonded to ground back at the panel) like me, I was able to successfully get all my paddle switches to work using the ground as the neutral to feed them power.


#7

This is very dangerous. And likely not to code. And likely a violation of your insurance policy. Please have this reviewed by a licensed electrician in your jurisdiction. The ground needs to be left as the ground. Adding it into the live circuit just creates all kinds of potential problems, including fire hazards.

Remember your goal is not to get this particular switch to come on. Your goal is to get this particular switch to come on while maintaining the fire and electrical safety integrity of your whole house electrical system.

@Navat604


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(Colin) #8

An electrician is not going to be able to tell you this is OK, but they could tell you off-the record that it will work. Grounds and neutral wires all go back to a common bus bar in the breaker box. If the neutral is a ‘home run’ and not tied into any other circuits, the only difference is the color of the wire. Everybody here had better know what they’re doing when working with electrical circuits - scaring them into calling an electrician or worse is not going to change their minds.


#9

It may “work” in some cases in terms of powering that particular switch on but I stand by the statement that it is not automatically the same as far as the integrity of the whole house wiring.

Submitted with respect.


(Colin) #10

Agreed. It’s not typically the best idea, but that doesn’t necessarily mean that in some cases it can’t be used safely. The installer just needs to be aware of what they’re working with.


(Ray) #11

Don’t want to turn this thread into something else but I highly doubt it any decent electrician would say it’s ok even off the record. A ground is not a neutral period. The last thing you want is the chassis of your washer as a current carrying conductor. If your house has a bonded neutral and ground then it should be at only at one connector and that is your circuit breaker panel and nowhere else. This is actually a huge safety issue.


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(Colin) #12

a ground and a neutral are both wires. unless they’re tied together with other circuits, and not a ‘home run’ back to the panel, there is no difference between the two where they both end up on the same bus bar in the box.


(Jason "The Enabler" as deemed so by @Smart) #14

Actually, you couldn’t be more wrong.
Do some research and learn about the purpose of the ground and the neutral.
You will learn that yes, they both tie into same bus bar.
But the important thing is what you learn about the other end of that wire.

Figure out what the ground is connected to, then figure out what the neutral is connected to.

You might find it a bit shocking.


(Doug) #15

It’s good to talk, but yes, sometimes everyone is an expert. We all want the same things, safety first and foremost, and for our fun home automation projects to work (very distant second). I’m an electrical engineer, not an electrician, but I know enough to be comfortable. I wish my house had a separate neutral and ground in the light switch boxes, but the fact is, it doesn’t. Like many other homes, all my neutrals are tied together to ground in the breaker panel. I did a fair amount of research before using my ground as a neutral for the purpose of powering a zwave switch. The amount of current drawn simply to power the switch is the key to everything in my mind. It’s not like i’m wiring a plug socket with no neutral wires. In this scenario it’s more about the path of current flow. You definitely don’t want a ton of current flowing over ground.

I’m happy to hear comments about this from licensed electricians. I think we’re lacking in comments from that demographic. Otherwise, I truly appreciate all who are looking out for the DIY crowd who sometimes know just enough to be “dangerous” (one of my favorite sayings btw)


(Jason "The Enabler" as deemed so by @Smart) #16

I will gladly admit I am not an electrician. I am however a very experienced electronics tech.

I just wanted to throw in my two cents for what it’s worth. If what I say helps great, if not, ignore it.

Not a worry, just here to help and learn.


(Ray) #17

I am an electrician and like everyone else on here. We are just trying to help each other really. If you think it’s ok to do certain thing then that’s your choice. Just respect others opinion and advice. Be safe guys. Do experimental on painting. trust me it’s much safer :wink:


(Ray) #18

Just think of it this way. A ground wire is like an overflow hole in your bathtub. It’s connected to the drain but it’s not the same. Using the overflow instead of the main drain. You will surely get a flood at some point.


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(Darryl) #19

Funny thing is, I had an electrician tell me that I could do just that, use the ground to the neutral. I wanted to research it, as it bothered me from a safety point of view. Guess I need to get another electrician to validate, or tell me the ability to run that neutral if needed. Most of my house has one, this one box doesn’t. :frowning:


(Brian) #20

Maybe a better analogy is that it’s like a copilot in an airplane. Sure you don’t need two pilots most flights. But when you do need them… well… Grounds helps electricity choose to go to earth instead of through you. For that reason, I treat ground pretty special, just like I’d treat a copilot. He’s got my back.

That being said, old wiring didn’t use grounds and people survived somehow. You choose your level of safety. Best course of action is to learn learn learn. If you know what you are doing, and do it anyways, you are in ok hands (your own). Others who trust you may or may not be so lucky, choose wisely for them too.


(Matt Hartig) #21

While it’s a bit off topic, I thought it would be appropriate to share some of the effects of different magnitudes of electrical current on the human body which were conducted by Charles Dalziel (inventor of the GFCI and professor of electrical engineering at UC Berkeley).

1 mA - A person is able to detect slight tingling sensation in the hands/fingertips.
1-6 mA - generally unpleasant to sustain, but a person still has the ability to release the energized object.
9-25 mA - typically painful and muscle contractions make it difficult to release the energized objects
60-100 mA - ventricular fibrillation (ie stoppage of the heart), inability to control your respiratory system

As you can tell it doesn’t take very much current before we get in trouble, so maintaining proper grounding is crucial to having a safe home.

(In case you were wondering I pulled the above information from an IEEE guide for substation grounding which references numerous papers written by Charles Dalziel.)