To understand why they are hooked in ONE place and it is safe, but not i multiple places requires at least a basic understanding of how electricity operates and moves in wires.
A good introductory physics book will explain how circuits work and how current flows in parallel legs of the same circuit.
Without at least this understanding it is very hard to understand what WILL happen if a groundED and groundING conductor are placed in parallel.

annie-lee,
you need your last post suggest that you don't understand how sub panels are wired. a 4 wire sub panel doesn't and shouldn't have the grounded and grounding wire tied together. period!!
a 3 wire sub panel must its own ground rod. hopefully both ground rods are in good condition.

ok. now you're wondering why???
ground loops...do you know what they are? no. then study basic electrical theory first.
remember this is the real world. wires, regardless of size, have resistance. V=I*R.

if current flows down a wire then voltage must exist.
voltage is required to over come skin resistance. did you know your skin has resistance? if the voltage over comes this resistance you have become part of the circuit...you're the light bulb.

if your following so far..
just imagine if that all the bare wires in your house are connected together and this one point connects to the neutral in your house. now if the connection fails and you're using this wire for current carrying. this wire is now at 120V above earth ground. touch this wire and earth ground..well you just became a light bulb...you might end up DEAD!!! or burned out.. I have heard of 2 people in NC that died because the metal box wasn't grounded. the hot conduction shorted thru the strain relief to the metal box making it hot to ground...they touched the box while standing on ground. now they're dead!!!

DON'T USE the BARE WIRE FOR CARRYING CURRENT!!!
NEVER!!!its there for your safety

You guys, just because someone asks fundamental and basic questions doesn't mean that his knowledge in the subject is so primitive.

In my last post, I was simply re-phrasing (narrowing down the scope) of OP's question: why can't we connect the neutral and ground wires on the same bus in the subpanel, when we connected them in the main panel anyway? This must have to do with the fact that the main panel is closest to the PEPCO's transformer, or not? Then why would someone make this statement below?

"The plain fact that they are connected to the same place at the BEGINNING of a system is inconsequential."

I think my question is very clear and this question may have been asked before. You may or may not have a answer or explanation, but then no one is obligated to reply in this forum unless he is please to do so.

if you connect them on the sam bus in a subpanel, then your ground from the sub to the main becomes a second neutral and is dangerous. NOTHING will be properly grounded in teh house anymore.

for example, here at work we had a problem for years with having between 48 and 90 volts from wall outlet ground to earth ground on our tower. sitting at hte bench if we hooked a radio to the tower transmission line you had to be careful or you got one heck of a shock! a couple months ago i decided that i would investigate to see what exactly was causing this. turns out that the breaker panel is a sub and is wired like a main, AND the grounds at the outlets were connected to teh neutral wire. thus when you touched the tower line which is truly grounded, you complete a second circuit for the neutral. the electricity flows on both paths, resulting in a shock.

electricity won't flow back up the ground from the main panel to an outlet, because there is nothing at that end to complete the ciruit and cause it to do so. same EXACT reason that a bird can land on a power line and be fine. as long as the circuit is not completed, current will not flow. all grounded appliances have the chassis hooked to the ground conductor, but isolated form teh hot and neutral. so even if you have a stove plugged in, the ground is still open to the electrical flow of circuit looking from the panel to the stove. but from the stov e to teh panel the ground is ready to carry any FAULT and trip the breaker.

think about this, your home plumbing supply line connects you to the water supply, be it muni or well water. the water flows ONLY towards your house. it will not flow from your house back the supply. if it did, then you would never have hot water becuase your heated water would go back out and feed the main line.

Annie, I'm not sure I can explain it any better, but I'll try.

The reason ground and neutral are separate is that they have completely different purposes.

The neutral completes the circuit for normal operation of appliances.

The ground wire is fastened to the metal parts of the electrical system, and (through the 3rd pin in the plugs) to the metal frame of large appliances. It's to keep people safe and prevent shock in case a short circuit in an appliance somehow shorts a hot wire to the appliance's metal frame, or a hot wire contacts the metal junction box containing the outlet. The ground wire then does its job, completing the circuit back to the panel, throwing the breaker or blowing the fuse.

You're right that both the neutral and ground eventually go back to the same place. So it still sounds like you could accomplish the same thing by connecting the neutral wire to the appliance frame, doesn't it? This might work for some hazards. But it would not work for others.

Let's look at a couple of examples. We'll consider your refrigerator circuit.

Normally, the electricity to operate the fridge comes out of the panel, through the hot wire, into the fridge (where it makes the fridge cold), then back out of the fridge and back to the panel on the neutral. I'll admit that's not a 100% accurate picture of how electric circuits work, but thinking of it that way makes it easier to understand, so bear with me.

Now suppose the fridge has been grounded by connecting its cabinet to the neutral, instead of to a separate ground wire.

Let's look at one scenario. Suppose a hot wire comes loose from the motor and touches the cabinet. Since the neutral is connected to the cabinet, BAM! You have a short circuit. The breaker trips. All well and good. You're safe. Using the neutral as a ground worked great - this time.

But suppose there's no such short, the fridge is just running normally. However, the neutral connection at the panel for the fridge circuit gets a little loose or corroded. (Yes, this does happen.)

A loose connection has trouble conducting electricity. Now the electricity is having a tougher time getting back to the panel to complete the circuit. Only part of it is able to get through. So, maybe the fridge is running a little slower than usual. You might notice this, or you might not.

The rest of the electricity really wants to get back to the panel, so it's going to take any path it can. As it turns out, your plumbing system is grounded to the panel. (Trust me on this. The reasons for this connection are beyond the scope of this article. ;-)

Suppose you touched the fridge with one hand, and the sink faucet with the other. Some of the electricity that should have been conducted back on the neutral now finds another path back to the panel - through the fridge's cabinet, through the faucet and plumbing, through the ground wire for the panel, the finally back to where it wants to be. Problem is, there's another conductor between the fridge's cabinet and the sink faucet - you. You may be shocked or even electrocuted.

Now, let's disconnect the neutral from the fridge's cabinet and connect a ground wire instead, the way the code requires. It goes directly from the cabinet to the ground and neutral bar in the panel.

If the wire comes loose from the motor and touches the cabinet, it will still throw the breaker just as it did when we used the neutral.

And if the neutral gets loose or corroded, the fridge still slows down. But now the neutral from the fridge is no longer connected to its cabinet. The electricity can't seek out that extra path through you and the plumbing. You're safe. You don't get shocked.

Does this explain it better?

Wow, thank you so much Davidandkasie and Davidr. It begins to make more sense for me. I was out of town yesterday. Your examples and carefully drafted scenarios really help to clarify things. I appreciate very much your time and thoughts. Here is my take on this subject and please correct me if I am in errors.

1. The connection of neutral and ground conductor at entrance is given and required by POCO, no choice there.
2. Any additional connections between the two conductors may result in ground conductor becoming a current carrying one which is not intended and may be a safety hazzard. This is demonstrated by your examples and scenarios.
3. The ground conductor will not become current carrying if the one and only (single) contact is at the entrance point. No potential difference can result on the ground conductor becuase on one side of the connection point both conductors have the same potential, and there is no circuit between the entrance point to the transformer (POCO) to possibly create any potential difference.

Again thank you all very very much!!!

"Any additional connections between the two conductors may result in ground conductor becoming a current carrying one which is not intended and may be a safety hazzard."

No, it IS a safety hazard.
The only question is if anyone will get injured, and that depends on exactly how much voltage drop is present on the groundING conductor when you touch it and another ground.

Annie, the neutral wire is a current carrying conductor therefore it must be insulated. If it is not insulated there would be a chance of the neutral load finding(touching) someone or something with less resistance to ground which would result in a dangerous situation because of the current that would be carried by this alternate path.
The ground wire is bare because in normal situations it is not current carrying. The only time the ground wire should carry any current is if there is a short to ground as in the case of a drill or frig motor going bad or any other fault conditions.

I'm in the process of designing a farming irrigation system and would like to use 8 irritrol 24v solenoid valves each activated by its own transformer. I'm not using a standard irrigation controller as I have available free an excellent swimming pool/spa control panel with 8 relays. I want to run 120v from each relay to its own transformer that I can mount inside a shed and then run 14 or 12 gauge wire to the valves. But I don't know what transformer would work and whether the cost might be prohibitive.

The irritrol ultraflow series 700 solenoid valve specs are as follows:

Solenoid: 24 VAC
Inrush volt-amp: 24 VAC-9.6 VA
Inrush current: .4 amp
Holding volt-amp: 24 VAC-4.8 VA
Holding current: .2 amp

Thanks for your help.

WHAT does this have to do with the original post or even any part of this thread?????

Are
the contributors to this discussion still available for comment? I ask, because
I had a situation where the neutral supply from the power company transformer
(about 200 feet away from my home) broke, or became open (eroded due to
insulation damage? - 3/8" insulated aluminum wire cable) between the
transformer and the secondary at the edge of my property. As a result, the
responsibility of the neutral to return current to the transformer shifted to
my earth ground and copper plumbing under my concrete slab foundation. I live
alone, so the opportunity to observe the change of operation of appliances and
lights was substantially reduced. I did not have a problem with breakers
tripping (200 Amp service panel) except when I ran an old air compressor on a
15 Amp breaker circuit. No problems on a 20 Amp breaker circuit.

I did notice lights
blinking at the same frequency as the agitation cycle on my clothes washer - my
only clue. Searching on the internet for blinking lights pointed me toward my
earth ground and improving its efficiency. Did everything I could, including
installing a second 8 foot ground rod. No change to the blinking lights.

My Open Neutral was
discovered, after developing a leak in my water pipes under the foundation.
Tunnels were dug under my home to expose the source of the plumbing leak, and
it was obvious that the 20 year old copper pipes were developing pin holes and
the metal was deteriorating. I had to have tunnels dug to follow all the copper
under the foundation and discover which pipes were affected.

One of the plumbers was
shocked while trying to replace some of that degraded copper line, shocked so
badly he could not release his grip from the copper pipe, as the floor of the
tunnel was wet. Fortunately, his assistant was with him and tore him loose.
Upon exiting the tunnel, that same plumber reached over to steady himself by
gripping the natural gas line feed (iron pipe) into my garage and was again
shocked. Emergency call to the power company. Technician discovered I had 88+
volts on my earth ground system - no idea how much current

I have two water heaters
for this house to split the load. One of the two water heaters was
electrically grounded to the service panel ground (also tied to the neutral in
the service panel). All the copper pipes connected to that water heater were
corroded and had to be replaced. The remaining 50% of the copper under the slab
was as good as new.

To the best of my
knowledge, this open neutral existed 5-7 years before discovery by a plumber
being shocked. Obviously, the power company does not inspect their neutral at
the transformer, or they would have identified the open between the transformer
and my secondary during the many years it was not operating. I'm lucky all my
gas connections are tight, but this same issue could account for some
mysterious home explosions. Also, since the plumbing leak occurred under
my slab, standard/basic home insurance does not cover the plumbing failure.
This failure by the power company to supply a safe product almost
resulted in a death.

Is there a question you meant to ask somewhere in this last post?

Yes - Thanks. I figure I need a lawyer with an electrical background to challenge the power company, since they will attempt to claim their responsibility stops at the meter, not with the copper pipes that failed after years of serving as the power company neutral. The lawyers I have talked with say I will have to have an expert witness, at substantial cost to me, to prove that copper pipes fail when continually used to make the power work in a home. This should not be the case when neutral is not even supplied to my secondary, and there is no neutral connection to the meter.. I'm unemployed and rebuilding my home, due to the flooding that ruined all my floors and baseboards, and I'm simply trying to discover how to get compensation for my losses by getting the correct advice on how to work this issue..

Mark, how's this going for you? I had a similar issue today and resolved it. My hot water heater started failed at the threaded connectors for both the cold line in and the hot line out. In the attached video, you can see what happened when I started disconnecting the hot side.

What's interesting in my case Mark is that turning off the main breaker at my house didn't stop the voltage leak. I ended up turning off the breaker at my neighbor's house and that stopped it. She had an open neutral on her feed from the pole, when the power company came and fixed it, they fixed it as well as a nearly broken neutral on my house.

My question is since this is before the breaker, isn't the power company liable for damage caused by improper wiring. In my house if the voltage takes a weird path, it trips the breaker, you know because of building code and not being stupid. But the electric company doesn't have a safety built into their system? It was running measurable AC voltage down my water line in the closet with my natural gas hot water heater! I'm amazed nothing blew up!

Kirk Meyers - Thank You for your insightful investigation and feedback. This is an ongoing pursuit, while having to personally repair my home. This degradation and breakdown of copper under the foundation resulted in denial of compensation by insurance, due to the nature of the standard H-OA (B) homeowners policy (which practically all homeowners have purchased). This means that I have to bare all repair costs. Tunneling and plumbing repair exceeded $30K, then the interior repairs of my home began.

Where are you located, and can we talk off-line or by email? You have important documentation and learning, also, and my situation resulted in a plumber being severely shocked - twice.

Mark

I modified hendricus's comment to give a full understanding of what is going on. Electricity is lazy. You have to force it to work. Any connection between L and N before say a light (a load) and the electricity will trip the breaker because this is a short circuit. After the light (load) the electricity will return to the panel and then to the transformer because that is the easiest path (path of least resistance). It will not go back down the bare wires (Ground wire) even though they are connected in the panel because it is easier to travel to the transformer than the ground. But faults are sudden surges which the transformer N point is not ready to accept within the time frame so these surges will go to the bare ground wire.

Sure Mark, email me at meyers.kirk@gmail.com I'm in central Arkansas. I've actually ordered a clamp type multimeter to test active amperage on my pipes. Sorry to hear about the insurance issues.

Prashobh_Karunakaran

Your statement is true, with the exception of a broken neutral circuit return to the transformer. (My neutral was broken in two places between the transformer and the secondary at the edge of my property.) Then, the lazy electricity has no option but to find another path to ground. In my situation, the only electrical path alternative was to follow Earth (green) through my water heater to the copper pipes under my foundation, and the inevitable stripping away of copper from the pipes until pinholes developed. The result was water damage inside my home.

Open neutrals are a serious safety hazard and more common that you might think. Even in large commercial installations. The high differential between the neutral and ground comes from the difference in the loads between the phases (120-0-120). When they are not perfectly matched, and they never are, power flows back through the neutral to the transformer. Typically the neutral is grounded at the transformer which is why the neutral moved off zero and the phases were at 120v. And this is also why sharing the neutral and the safety ground is not a good idea. Not to mention all the wiring errors that are so common that would be an instant safety hazard.

I would look at the State utility rules on where their responsibility ends. Here in California its at the meter. If something upstream fails they are on the hook. Further (this is the USA of lawyers of course) you may be able to sue the utility and it sounds like you would have a good case. A jury would relate to getting shocked as you described. Its worth talking to a lawyer when that much money is at stake.

Thank you for your advice, 1audio. The more I dig, the more I learn. I've talked with a couple of lawyers, but those with whom I've talked lacked the expertise in electrical to argue and indicated a professional witness would have to be hired to prove the evidence. Since there was not a death, their compensation would be limited. My challenge is to find an Attorney with the electrical background to resolve this dangerous situation and keep someone from being electrocuted to death before is resolved. If not concluded successfully, it will result in further "insulation" for those who should accept responsibility. In the meantime, I'm researching to develop alternative safety measures. While 120 VAC in residential is enough to easily kill, I can only imagine the impact of a similar situation in an industrial situation. Presently, National Code requires the Neutral to be bonded to the Earth Ground in the Service Panel. When the National Code was originally written, I don't imagine they imagined how nicked Neutrals rot in the ground and become open. This is why all specifications need to be reviewed and revisions made on a periodic schedule - variables can change and new variables become overlooked with an outdated series of checks. I've addressed this many times during my involvement with R&D. The goalpost of "perfect" continually moves, no? I possess the evidence.

PM me and I'll give you the contact info for a professional witness with experience in this stuff. Finding a lawyer will be harder. What you are hearing is typical of lawyers out of their depth. My guy may be able to help you since he has worked all around the US.

This is actually a good reason for overhead wires. They are much easier to maintain. But no one thinks to actually maintain this stuff. I had a problem with the drop from the street (overhead) where an aluminium clamp connector had rotted over 60 years to the point that it would arc, A bear to troubleshoot and impossible for someone without the specialized equipment I have. My utility came out and once they under stood, fixed it on the spot (9 PM on a Saturday) at no charge.

In industral applications there are usually a number of places where these issues will show up quicker. Lost phase will damage big motors and drive systems so they have protections. Lost neutral is a common problem in commercial building when the power is distributed in cubicles. A surge suppressor would have alerted you to the problem, but not in good ways. The cheaper ones will smoke and hopefully not catch on fire. The better ones will sound an alarm.

The safety ground's function is to pass enough fault current to pop the breaker. That's why it needs to be big enough to pass a lot of current even if its not normally passing any. That's also why it needs to be bonded to the neutral at the panel for a low resistance path. A cold water pipe many not be low enough resistance back to neutral. Current practice is to depend on GFCI's for that since they are far more sensitive and usually will catch problems that a ground connection could not. It would be easy to make a device that shows excess voltage between neutral and ground (there are commercial testers that do this). Seeing 3-5V difference is not uncommon and usually not enough to be a concern. 20V or 50V is. Application in a way that a homeowner would be aware is the larger issue. "Internet of things" to the rescue?

My situation persisted more than 6 years before discovery, and I prefer to be over prepared before contacting the provider. My ground was measured at 88 volts within 30 minutes of the plumber being shocked. The main breaker never tripped.

Send me an email address, if you would, to my twitter account: Mark Fant @ macfant and we can discuss offline.

Many thanks,

Mark

Oops, I don't have twitter. Send me a note at demianmDOTpdsATgmailDOTcom and we can take it from there. I did not realize they have no PM capability here.

I have an update for those interested. The following video provided understanding I lacked and presents it in an easy to understand presentation.

https://www.youtube.com/watch?v=-n8CiU_6KqE

It is not good practice because if the ground becomes disconnected at the panel (or anywhere back to the panel) it essentially becomes hot in series with the disconnected device that you cheated the neutral to ground on. So if you contact this disconnected ground(which is potentially exposed on numerous devices) and real ground you will be in series with the disconnected device and hot, not good.

REAL GROUND------------YOU----------|
--DISCONNECTED GROUND--------- ^-----------LOAD----------HOT

Lets say you cheated the neutral on your washer and tied it to the ground. Now for some reason the ground becomes disconnected on its way back to the panel. You turn on the washer and it doesn't turn on, no big deal. But now the chassis of the washer is connected to hot through the washers motor winding. You now touch the chassis of the washer and then the dryer (which has its ground still properly terminated at the panel) at the same time and you now complete the circuit, HOT--MOTOR---WASHER CHASSIS---YOU---DRYER CHASSIS, and you now get fried.

Hopefully this makes sense in a nice practical example. It is not a safe practice.

donnellyjt and annie-lee I know it was a long time ago, but I hope this helps.

Well, just had this 'experience' last weekend when a branch from a neighbor's crappy sweet gum tree fell onto the service drop as remnants of Hurricane Hermione passed by. Only the neutral wire - and the tension wire to the stand-off - actually broke.

Lights began flickering and/or dimming/getting brighter. The two 'hots' from the PoCo's pole were laying on the edge of the roof and the metal drip edge. I was concerned....

Of course, the PoCo had bigger fish to fry with thousands w/o power. Even called the fire department, but when they came by, they said that they could not do anything until the PoCo dealt with the branch and cable first. "Call back if it catches fire...." I was MORE concerned.

Nine hours later, I decided to check things out with an auto-ranging multimeter. Drove an aluminium rod into the moist earth at the corner of the house closest to the problem. 14 v potential between the downspout and the rod! 15.7 v between a nearby, unused hose bib and the rod! Even got 2 v on the downspout the farthest away. More concerned calls about an apparently 'energized' house....

Standing a fire watch on your home is unsettling. Flipped the breakers, leaving only critical circuits on, namely the 'frig, freezer and one lighting circuit so that one bulb might give a clue as to what was happening.

PoCo showed up at 3 AM. The tech said he had already been 'on' for 24 hours and wasn't expecting to see a bed for another 24.... Donned his gauntlets and pitched the offending branch back from whence it came. Neutral and full/safe service was restored in short order.

This 3 AM lesson illustrated what can happen when neutral goes away....

Cheers

apg4 - you handled the crisis well - congratulations. With the neutral line from the power company transformer open, all current being used by appliances was routed to your home Ground plane. It did what it was supposed to do and acted as a safety net. My primary beef with that process is that there is no system in place with the power company where they can easily identify the change in the current return from a user. The plumbing and electrical framework, as well as any metal natural gas lines attached to the building, are all linked together to dissipate sudden and momentary electrical spikes - according to building and NEC codes - but prolonged electrical demand on the ground system of a building causes the ground system to degrade until it also fails. That is, if a fire (or gas explosion) does not start first and destroy all evidence of an open neutral. A normal ground system should have little to no voltage - especially no voltage capable of killing someone.

If you have not already, check out the video Kirk Meyers shared. Your hot water heater would have acted the same way if you had tried to disconnect the plumbing. I had the same happen to me, but the only time I saw lights flicker was when my washing machine went into the agitation cycle or there was a high amperage tool in use. Problem for me, though, is I live alone and when there was an opportunity to see lights act different, I was seldom around lights and was working outside the house (electric saw, power washer, etc.). I'm now attempting to get an update to the National Electric Code (NEC) to include a periodic check for the health of the neutral - at least for the part connecting the meter to the transformer. The neutral and ground circuits inside the house have little chance of changing on their own when wired correctly, but by the same token, when the neutral supply to a meter is broken or open, all ground fault interruption and breakers loose their efficiency to protect lives. I had an open neutral for 8+ years and it never threw a breaker or tripped a GFI receptacle. It wasn't until a plumber was shocked with 88 volts from a copper pipe (and was not capable of releasing his grip from that shock) that my situation was identified. All internet information 5 years ago (that I could then find) referenced correcting the ground pole connection to earth to resolve blinking lights. Little did I know then that my grounding rod had almost 90 volts of electricity. It would be wise to always test the electrical potential of the ground plane in a building before repairing or disconnecting any lines. No one expects to be shocked when handling a ground circuit.

Thanks.... Once I removed all extraneous loads, the lights never blinked/got brighter again. I assume that happened whenever there was 'competition' for the available ground. I upgraded the main panel a dozen years ago, part of which was the installation of a new copper ground rod. With the neutral conductor now separated, the return current was 'finding' a path wherever it could: to the drip edge, gutter and then downspout in addition to the ground rod and/or bonded copper plumbing.

Which brings up another question. Soon after upgrading the main panel, I installed a 100 amp, sub-panel in the new greenhouse to provide 240 v to the adjacent hot tub. Another ground rod was installed adjacent to the panel. (All work was done with permits and inspections.) The brand new NEC did not require a ground connection between the two panel boxes, so only 3 conductors were pulled through the conduit. The inspector - using an older NEC - said I needed 4...until I downloaded the relevant citation in the brand new code and the inspector signed off on the work. I believe subsequent NECs may have rescinded the 3 conductor rule. Reason?

I'm not qualified to answer NEC questions, but the following is my guess. What I have read is as of the mid to late 90's, all 220 VAC required connection to ground. This corresponds with the electric dryer plug changes from 3 to 4 pole plugs (3 pole = 2 x 120 and one neutral, 4 pole is the same but adds an Earth Ground run all the way back to the Service Main panel. Since you have a sub-panel with 220 potential, it was set up just like your home with its own independent ground circuit and a supply that linked to the 3-wire input of your Service Main breaker (not being fed through breakers in your Main Panel). That way, if there were any shorting in that remote panel, it would have a shorter path to ground (less delay or error) and would not interfere with the operation of the home. Could be, also, that the potential current draw of the new 100 A sub-panel required its own ground circuit to comply with code. Perhaps there is an electrician out there who is familiar with NEC, as it is updated every 4 years.

As a side note, the electrical resistance of the neutral circuit is significantly lower than the Earth Ground circuit. The calculation for how much current to charge to a customer's meter is based on the load resistance to the meter. Could it be that one of the reasons why the power companies are so reluctant to maintain the integrity of their Neutral circuits is that they sell more current when there is a higher resistance (ground to earth instead of Neutral return of current to transformer) and to fix those "leaking pipes" would result in lower revenue? Think how much energy is wasted, especially when systems get close to capacity limits. Think about all the lives endangered because of those "leaking pipes". Just wondering . . .

Interesting...so if I super-cooled the meter, I could get free 'lectricity? ;-)

Cheers

Annie-Lee, not only for you, I think you got it but there are others that are reading this and might not understand. This is my take.. hope it helps...

Electricity requires a "circuit" to work... in and out. Okay so you bring a single wire from transformer and connect to on side of a light bulb, you get nothing (hopefully your not grounded and touch the wire).

Then you put a metal rod in the ground and connect a wire from it to the other side of the bulb that has a pull chain. Then you pull the chain and light comes on... You have now created a circuit. Like lighting touching ground and lighting up the sky.

Now if someone touch the un-shielded wire from the transformer, boom. While the light is still on, someone touched the metal rod, boom...

So then for safety purposes, they shield the wire coming in and they ground the rod by the box and we return a "shielded" (common/neutral) wire to the box to complete the circuit (Thus both ground and common connected). Now we also ground the pull chain so any unused voltage will return on that copper wire and into the earth so if someone touches the bulb or chain they don't get shocked.

That is why almost all electrical appliances have the ground (third) prong wire to avoid being shocked while opening a fridge. The ground wire should be attached to every switch and plug in your entire house so it works that way. Now if the return (common/neutral) was not shielded, then it can touch the ground wire (or other grounded source) and complete a circuit and boom.

I am not an electrician and didn't go to school to learn this like the pros here that were trying their best to answer questions but some people think that all you need is one wire and that is not how electricity works... if it did, birds would fry when they stand on wires... lol, some do when they touch two or ground themselves.

Hopefully this clears some minds that might not fully understand how an electrical circuit works.

It was really entertaining to read all the examples but I would have used the blood stream since they both connect to the heart but one is going and one is returning instead of a faucet... lol...

NO please don't get this going again. Hahahaha hopefully there are no heart specialist reading this and set me straight, lol.

Thanks to all the professionals for taking their time to help us understand electricity a little better.

It appears that this all started out in 2007 with the following.

(The ground and neutral wires are connected to the same bus in the breaker panel anyway. The only issue I could see is that the ground wires are not insulated the same as neutral. What are the other reasons?)

Electrical power will always take the least resistance and path to ground if properly grounded thru rod or rods that are 8' in length and pounded into the earth. Not only is the Main Breaker panel neutral bar grounded there is also a GREEN bonding screw on the neutral bar that bonds the metal enclosure to earth thru the grounding system. Touch any energised hot wire to the metal enclosure and bang goes the circuit breaker because of the grounding not the neutral.

2 stories from past clients issues will explain why grounding is so important.

(1) older lady who touched anything metal in her house got shocked ( metal heat vents, water faucets, ect. 6 other licensed electricians tried to figure out why and all failed. My solution was to pound a new ground rod to short out the circuit breaker that was causing the problem. In short what it was discovered that a HVAC tech had replaced a item in the furnace and pinched a wire causing this problem. By not having a true grounding correctly the circuit breakers could not trip properly.

(2) Client dropped a 120 volt ac fan into a hot tub while they were enjoying themselves and never received so much as a tickle of a shock. Why? The fan was on a GFCI outlet and the hot tub was on its own GFCI circuit breaker. When these 2 different voltages came into contact in the water they both tripped and saved the hot tubbers from electrocution .

Just because you can or might be able to use the ground as a neutral don't do it, it's not the way that things are designed and or planned for.

www.dbelectric.us

Great examples - thanks. Consider this, though. All safety devices (fuses and GFCI) require a neutral that connects back to the power company transformer. In my case, the Neutral current return cable from the transformer to the secondary (at the edge of my property) developed multiple shorts and provided no return path for purchased current. Since NEC code requires the Neutral to be bonded to the earth ground (in the service main - primary breaker box) as a safety backup, all current that flowed through my meter went back to ground using my copper plumbing system - it had less resistance than the 2 ground rods next to my service main, Never tripped a fuse or a GFCI - over a period of many years. After about 6-8 years of stressing my copper pipes with draining current to ground, 50% of my copper pipes (the same 50% directly bonded to the earth ground back in the service main) developed pin holes (that leaked under my slab) and the result was extensive damage to carpet and wood floors. To add insult to injury, plumbing leaks under the slab are seldom covered by home owner's insurance and slow leaks usually result in airborne allergens in a closed environment. That situation resulted in liver failure and almost death - over two weeks in intensive care. All because checking and ensuring the health of the neutral circuit is not part of code - not yet.

Actually, a GFCI doesn't really give a hoot about how the neutral is connected. It's merely measuring an imbalance in the current carrying conductors.

Ron N GFCI circuit breakers tie directly to the neutral bar
and the home run neutral for the GFCI circuit opening or openings ties to the
GFCI circuit breaker not the neutral bar. So I am wondering why then does the
neutral not give a hoot how’s it connected as this is the proper connection for this load control?

I'm not in the electrical trades, but it is my observation that if the neutral is not functioning, then an imbalance cannot be sensed. My neutral was broken for years before plumbing repairs brought the problem to light - with a plumber being shocked to the degree where he could not release his grip on energized copper pipes (that took current to ground, but were "floating - not grounded to earth") in open tunnels so that degraded pipe could be located and replaced. Emergency response from the power company determined that I had 88 volts on my "ground". God only knows how much current. Doesn't take much current to kill - my point.

The GFCI has a neutral pig tail because if you don't connect it, there's no current going to flow through the device, but it is not correct that the neutral to be connected back to the POCO as the original poster said.

In fact, a 240V GFCI that has no neutral load doesn't even have one of those pigtails.

The point was that it cares not about the quality of the neutral (or even that it is a neutral at all... you can connect a GFCI to an circuit isolated from earth ground entirely, and it will still work.

The problems I survived resulted from an Open Supply Neutral (burried 3/8" aluminum cable running from power company transformer to the edge of my property). There were two failed locations in that cable in less than 200 feet, an all cable problems were not even on my property and were on power company right-of-way. Had exactly the same electrical effect as if the Neutral was not connected in the Service Main. In that circuit, the ground and neutral were in parallel and the only path to ground was through my plumbing. Turned my plumbing into a sacrificial anode and I got stuck with the bills.

I have read much of this thread. One point made was that if you use the ground wire in place of the neutral wire, then you are eliminating the the ground. I am curious about this discussion because I would like to install a smart switch (and don’t have the required neutral wire). couldn‘t I use the ground as a neutral, and then use the switch box itself to ground it? In other words, I would hook up the ground wire from the switch box to the neutral wire coming out of the smart switch, and then I would use the ground wire coming out of the smart switch and connect it to a bolt in the switch box itself to ground it. is this not feasible?

No. It will "work" in that your switch will be energized, but it won't be safe .

I suggest that you read the entire thread. Note that there are several posts at the top that don't display until you click on a link. The reason what you're proposing isn't safe is explained pretty well.

Homes are built with the cheapest possible materials and least possible amount of labor, to minimize the buyer's cost and maximize the builder's profit. Today's COMEX copper price is $2.64 per pound. Adding a ground wire to 2-conductor NM cable increases its copper content by 50%. Do you think that builders would use a separate wire for the ground if it wasn't necessary for safety?

The switch box could be either plastic or not grounded.

This discussion reminds me a little of a bath light-heater-fan installation that I ran into many years ago. It had probably been installed in the early 1970s.

If you've seen one of these units, you may know that you normally need 3 hots and a neutral for power and control. (Modern ones may have found a way around that, I don't know.) But 12/4-g NM is hard to find, or at least was back then, so the usual code-compliant method was to use some kind of raceway and pull THHN.

But whoever installed this one did it with 12/3-g. And here's the weird part, he used the bare ground not for the neutral, which though not to code would have made sense, but for the hot that enabled heat! It's just sheer luck that no one ever touched the fan housing when it was operating, because it WAS live. To make things worse, he also mounted the unit within easy reach of the shower. :(

The neutral wire provides the path back to the earth while the ground wire is protecting the structure. When you use the ground wire as a neutral wire, you defeat the purpose of the ground wire, which is to protect the structure.

Since this is now a discussion of hots and shorts...an interesting thing happened just the other day, The 20-25 year old GFCI in the bathroom died. There was only one other outlet on the circuit, an outside weather-tight box. No worries, simple replacement.... While not a professional, I know my way around 'lectricity....and respect it. (Got tagged by 12,000 v DC once from a neon sign transformer. I had built a functional helium-neon laser in 1968.) When it was time to change out the main panel box and upgrade from 100 to 200 amps, I pulled the ticket and did all the work myself and got high marks from the city's inspector. Also installed a 100 amp sub-panel in the greenhouse, and recently hard wired an 8kw, tri-fuel generator into the main panel via an interlock on the main panel.

But back to the GFCI...installed the replacement, but it didn't work. At all. The reset button didn't seem to 'click' when pressed. My meter said the power feed was 118.3 v. Further investigation once removed revealed no continuity between anything. Carried it back and the hardware store gave me another. Same dam thing when installed: 118 at the feed lug, nothing anywhere. So back to the store with the second bogus unit and my meter. Demonstrated for the assembled crowd the lack of continuity and the non functional reset button. Grabbed a third off the shelf. Same story. Open circuits throughout.... *Three* bad right out of the box? One store guy opined that the reset button wouldn't 'reset' without power, but the first two had a proper input voltage present and the reset button still wouldn't engage. So I got my money back and bought a AF/GF breaker for the main panel.

Everything works now, but I still can't understand why three Leviton GFCIs could be bad right out of the box...

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Now I'm wondering if the neutrals in the house may have been tied to the ground somewhere in the house before it gets to the main panel. If that is the case, I wonder if the GFCI's can sense the imbalanced load from the other devices in the house? I would try not installing the ground at all and just the hot and neutral and see of that does the same thing. Also I'm wondering of the hot and neutrals got switched somewhere, making the terminations backwards? Interesting to say the least. To check that, I would test the hot to ground and then the neutral to ground and see what each says

The ground and neutral should NOT be connected at the same place in a panel. The neutral buss bar is isolated from the panel and the ground buss bar is in direct contact with the panel. The neutral should only be ”grounded” at the service. One is a grounding conductor (bare copper or green), used to protect people and equipment by tripping (opening) circuit breaker due to ground fault. The neutral (white or gray) is a return path for current on the circuit and can kill you. Especially if used as ground and neutral. Basically a booby trap!

Quite true...as I found out a few years ago when a limb broken by a passing (dying) hurricane broke the neutral conductor - but not the the two 'hots' - at the service drop. The lights throughout the house were flickering. The damage was obvious, but the fire department wouldn't touch 'em 'til the PoCo dealt with it. "But call us back if you see smoke...."

As it turned out, a hose bib close to the action was reading 14v, while a downspout was reading 16v to ground. The ground rod was now carrying the full load, and the copper water lines were part of the circuit too. Reduced household loads to a bare minimum and stood fire watch for about 12 hours until the local utility showed up. Branch removed and the neutral conductor was promptly fixed. But the ground circuit functioned entirely as intended - and installed - by me.

I install hundreds of GFCIs every year and have literally never had a bad one out of the box. You sure you were connecting to the line terminals? Like the guy said, if there's not voltage between the two line screws, they will never have continuity to the load screws.

I did have an issue once with a modified sine wave inverter where newer GFCIs wouldn't reset, so I found a large box of old ones on Ebay that work great for that.