120 V between Ground and Neutral?


Wires are reversed, possibly at the outlet you're measuring at. Find the circuit's breaker and pull the outlet and make sure green or bare copper goes to green, black to gold and white to silver. Make sure any pigtailing is properly done. Find all other outlets on the circuit and check them as well. Get a 3 prong outlet tester with little neon lights to test each outlet for correct polarity and grounding ($5)



If all the outlets pass but the lamp switch wiring is still screwy, then I would suspect something a little more difficult to track down. Is that switch a dimmer, timer or other powered switch? I often find people perplexed when installing these devices in a lamp fixture circuit that doesn't have a neutral wire so they pull one from somewhere else, often with very bad results.

-- Bobby G.

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Depends where in the world you are.

Most mains AC electrical supply these days is three phase to the local substation. This may be a transformer on a pole near you supplying overhead cables or a transformer in a compound, with underground cables.

Three phase means that the are effectively three elctricity supplies on three separate cables.
As you know, with AC the voltage varies periodically, rising and falling with time.
The three phases are carefully controlled so that when one is rising another is falling.

On any individual phase once the current has passed through your load it is returned by your neutral connection to the substation.

Here the magic occurs, because the rises and falls in the different phases are at different times they nearly cancel each other out, leaving only a small imbalance current.

This is fed to earth at the substation.

Your neutral should not be earthed at your local distribution board as this nullifies the...

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The hot being attached to the ground woudln't make the neutral line 120V. Also, I couldn't have had a 120V potential between the hot and the ground if this were the case.

Thanks anyways.

I am glad you solved your problem before it caused a much bigger problem.

As for my comment, I was referring to wiring of a single receptacle. If Black is wired to ground and ground to where Black should be (i.e., the connections are reversed at the receptacle), from the receptacle side, you most definitely will see 120 V between what should be hot and ground and between neutral and ground. There will be zero volts (or close to it) between hot and neutral, as hot is actually ground in that situation. That was only one possibility, but it is why I asked whether you had pulled the receptacle from the wall.

A short between white and black should blow the breaker, if it is low resistance. If it is high...

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Basically, a Neutral is a current carrying conductor at zero volts with respect to "earth", while a Ground is a non-current carrying “Safety” conductor. The Ground is there to carry a fault current back to the panel board to ensure that the circuit protection device will safely trip in the event of a fault (as opposed to an overload). An overload current generally returns via the Neutral. Additionally, the Line wire is the current carrying conductor operating at 120 Volts (USA) or 220 Volts (Europe) with respect to ground. Both the Neutral and the Ground wire are bonded at the panel board to earth (via a ground rod or equivalent) and bonded to water piping in a typical home or building (with metal piping).

By the way, any cable, TV, phone lines, etc. must also be bonded to the common earth ground. This provides a degree of protection in the event of a lightning strike as well as ensuing that signals have a common reference voltage inside the building.

More detail:

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Neutral vs Ground

If your dad has decided to go for complete renovation and repair of the old house you have been living in since your childhood, chances are that you would find just two wires in the electrical wiring. One of these wires is called live while the other one is neutral. In US, Canada and all countries where 120 volt power is carried to homes through these two wires. Live wire is also called hot wire as it is the wire carrying current while neutral wire is the wire that completes the return path without which current cannot flow. A grounding wire (also called earth in some countries) is a wire that is ready to take all the current into the ground in case of a mishap such as high current generated in an appliance. This is the wire that your dad will get installed if electric wiring is being changed altogether. Though both neutral and ground wires are for the safety of the building, wiring system, appliances and human beings, there are some differences...

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Understanding Neutral versus Ground

The grounding of electrical equipment is probably one of the least understood aspects of electricity. As the characteristics of electrical equipment changes from linear to non-linear, the nature of grounding expands from the task of insuring the safety of personnel to insuring that one type of electrical equipment does not interfere with other types of electrical equipment. One point for confusion rests with the often interchanged terms of Neutral and Ground. Many articles have been written concerning the problems with 3rd harmonics overloading the neutral conductor. Many articles have been written concerning the problem of electrical ground noise. Even with all these articles, there still exists confusion concerning whether equipment should be connected to the neutral or connected to a ground.

It may be possible that a simple rule would clarify the differences between Neutral and Ground.

It can be stated that Neutral...

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Main Difference – Neutral vs. Ground

Electrical devices are connected to a typical single-phase system via three types of terminals: neutral, ground, and live. Sometimes, the ground terminal may be absent. The live terminal is connected to the alternating power source. The main difference between neutral and ground is that neutral provides a return path for the current in order to complete the circuit, while ground connects metal parts of a device to the earth in order to provide a safe path for current to flow though, in case a wire becomes damaged and metal parts of the device starts conducting current.

What is Neutral

Every appliance connected to an electric circuit must have at least two terminals. Current should enter the device through one terminal, and leave through the other. In ordinary domestic electric circuits, every device is connected via a live and a neutral wire (in three-phase systems, a neutral wire is not necessary, but we will restrict our...

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Power quality from various backup devices

Recently I have been having discussions with some of my colleagues regarding different types of power backup devices - specifically, why some UPS units, inverters, and generators cost a lot more than others, and whether or not it was worth paying the higher price. To illustrate some of the points I was trying to make, I borrowed an oscilloscope (specifically, a Fluke 98 Series II Automotive Scopemeter) and took some measurements of the power produced by various backup devices.

Notes about reading these scope traces: The grey line on the left of the plot shows the trigger point, and the step icon shows the trigger level. The little black rectangle towards the right of the plot shows the zero voltage level. All plots were made with the scope in DC coupled mode so that DC offsets in the AC signal would be shown. As I did not have a printer or PC interface for the scope, I had to take pictures of the scope screen with a digital camera....

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Hi, I'm Mike and I'll be glad to assist you. You had a bad connection on a neutral in an


ahead of where you tested. I'll give you a procedure, that most times pin points where. Let me know how you do.

Wiggle Procedure

You have a circuit with dead outlets and maybe some dead lights on it or you’re experiencing flickering on a circuit. You will need a 2 wire voltage tester to check the outlet. A Multimeter or a Volt/Con are suggested. I prefer the Volt/Con because there are no settings to make, it does continuity and is audible. Success begins with knowing what you’re looking for.

1] No voltage reading between the hot and the neutral or ground indicates an open hot.

2] No reading between the hot and the neutral but 120V between the hot and ground and 120V between the neutral and ground indicates an open neutral.

3] No continuity between the neutral and ground – Check for tripped GFCI device first

4] If all the branch...

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Neutral vs Ground - Difference between Earthing and Neutral

The Neutral and Ground are generally connected together at your service panel, not at your devices. At the device, neutral is the path for return current. All the current that comes "from" the hot leg "returns" through the neutral wire. I'm using quote marks because current actually alternates directions in an AC system. Hence the name AC.

Anyway, the ground wire should only carry current in the case of a fault condition. In the USA, residential ground wires are often just bare, uncovered copper. When plugging in a grounded appliance or other device, the ground wire gets attached to the chassis.

In this video I will explain difference between neutral and ground.

more videos:-

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10 Common Electrical Engineering Interview Questions and Answers (Part 05)

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Answer for USA, Canada and countries running a 60 Hz supply service. The bare copper "earth wire" normally carries no current. Its purpose is to provide an emergency path for any accidental contact between a hot wire in an appliance and the metal parts of the appliance that the user may come in contact with.

In North America both the "neutral" and the "earth ground" wire are connected together at the household's circuit breaker panel and both are connected to a ground rod near the utility meter.

For 120V circuits, the "neutral" is distributed in the house wiring as the white wire of duplex wiring. The black wire is hot. The "hot" wire is protected by a circuit breaker. In most households built since the 1950s, the power is distributed with a ground wire as well. This wire is a bare copper wire in the same sheath as the white and black wires.

In a properly operating circuit, the current supplied through the black wire is returned to the circuit breaker...

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If you’ve ever had the pleasure of upgrading old electrical wiring in a residence, you know that a separate earth ground wire was generally not used in the past. In such cases, you find yourself with 2 wires: live, and neutral.

Now, you might want to install a grounded outlet without redoing a lot of wiring. A common method of getting around this little problem is to install the new 3-conductor outlet by tying live to one prong, neutral to the other prong, and then using a jumper wire to connect neutral to the ground connection inside the outlet.

“Theoretically, this should work just fine!” you reason.

It turns out that theoretically, you are in fact correct. Practically speaking, adding a “ground” in a 2-wire installation by tying neutral and ground together has several serious – and possibly dangerous – drawbacks.

Here’s the scoop.

This here post assumes that you actually have some idea of how AC power systems work. Obviously, if you know very...

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Basic Electricity

Basic electricity:

Electricity is the flow of electrons from one place to another. Electrons can flow through any material, but does so more easily in some than in others. How easily it flows is called resistance. The resistance of a material is measured in Ohms.

Matter can be broken down into: Conductors: electrons flow easily. Low resistance. Semi-conductors: electron can be made to flow under certain circumstances. Variable resistance according to formulation and circuit conditions. Insulator: electrons flow with great difficulty. High resistance.

Since electrons are very small, as a practical matter they are usually measured in very large numbers. A Coulomb is 6.24 x 1018 electrons. However, electricians are mostly interested in electrons in motion. The flow of electrons is called current, and is measured in AMPS. One amp is equal to a flow of one coulomb per second through a wire.

Making electrons flow through a resistance requires...

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As the neutral point of an electrical supply system is often connected to earth ground, ground and neutral are closely related. Under certain conditions, a conductor used to connect to a system neutral is also used for grounding (earthing) of equipment and structures. Current carried on a grounding conductor can result in objectionable or dangerous voltages appearing on equipment enclosures, so the installation of grounding conductors and neutral conductors is carefully defined in electrical regulations. Where a neutral conductor is used also to connect equipment enclosures to earth, care must be taken that the neutral conductor never rises to a high voltage with respect to local ground.


Ground or earth in a mains (AC power) electrical wiring system is a conductor that provides a low-impedance path to the earth to prevent hazardous voltages from appearing on equipment (high voltage spikes). (The terms "ground" and "earth" are used synonymously here....

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As from my own experience in wiring houses, all three wires run from the breaker box to an outlet together, in fact, they generally come in a roll encased together. The grounded wire goes to/from the breaker box along with the hot and neutral. In many cases, a single room is on a single breaker. This is done by running the three wires from one outlet / light to another, and in these cases the ground does not directly go to the box/ground outside. It goes to all the other outlets between the outlet and the breaker box in the circuit, and then to the breaker box, and then to the earth.

There is a physical pole buried in the ground in my yard which is connected to the ground in my breaker box. The neutral is intended to carry current, and the ground wire is basically an added safety. Many old homes did not have 3-prong AC outlets

Just so we're clear, I am not a pro electrician. So I might be wrong on some...

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in a typical electrical system in a home, the voltage is 220 volts, center tapped to provide 2 120 volt legs.

heavy appliances like a stove, clothes drier, or water heater, are most likely hooked across the two "hot" legs to give 220 volts, and more efficient transfer of energy.

common low power devices use only half that, one input of the device is connected to one of the two "hot" legs, and the other is connected to the center tap.

at the point where the three wires from the service transformer enter the house, the center tap is connected to an earth ground.

at THIS SINGLE PLACE ONLY, the neutral (white in the US) wire and the ground (green, conduit, or bare copper in the US) wires are all connected together. In some homes and most commercial installations the ground is conducted by a metal pipe called a conduit.

the NEUTRAL wire is the return path for appliances that use 120 volts, it is NEVER fused.

a ground wire is used to convey the ground...

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Just kill the power source at the main breaker or fuse location then grab the ohm meter and read the netural and ground you should be super low on ohm reading { less than 3 ohm is max } but before you start doing that.

Just grab the Ohmmeter leads and touch each others to see how far the needle or the digtail dispay go down to at what number and you may need to fine tune it if necessery but with the probe leads touch each other during ohmeter mode it should slam all the way down to near zero or at zero.

Once it is correct reading then do it on the circuits { please have power off on this one otherwise it will affect the reading when the power is on and it can wreck your ohmmeter as well } then find the netural and ground in your receptale or swtich box and read it from there you should have near zero reading.

That is good sign of connection but I still rather double check all the receptale and switches if you still supect pretty high reading { not at zero number }...

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Way back when, it was legal to either send neutral current back through ground, or ground major appliances to neutral. I don't remember which it was, but it was legal - and now, in many cases, it's grandfathered.

If the instructions say it can be configured for 3-wire hookup, but the third wire is called "neutral", then they are talking about grounding to the neutral - or else not grounding at all, which I highly doubt is the case.

In either case, there is no logic supporting the idea that the oven's 3-wire option is any different from the old grandfathered 3-wire configuration. The original poster quite clearly has two hots and a "ground", and I am betting it's a piece of SE - which is so incredibly COMMON around my neck of the woods that I'd have a very hard time believing it wasn't originally legal (I know it's not now).

The OP needs to configure his oven for a 3-wire installation and connect the third wire, whatever he chooses to call it, to...

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You have an open neutral wire somewhere in the branch circuit. 120 volts between ground and neutral is due to other loads on the circuit. 0 volts neutral to hot indicates open in the neutral white wire. Use of digital multimeter is fine but you must understand what the meter is telling you in house wiring situations. If you connect a analog multimeter or neon tester between hot and neutral needle will register minimal voltage and the two wire neon tester will not light up.

Turn the breaker off and find everything on the circuit that isnt working. Power off!! Look in the working outlet boxes for a poorly connected or disconnected neutral serving onward power to the non-working outlets. If nothing is found then start checking the non-working outlets. It could be in a switch box, a receptacle box or ceiling box.


Last edited by Stubbie; 08-18-2007 at 12:04...
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Power quality questions continue to revolve around one underlying issue related to electronic equipment: its ability to withstand the effects of electrical interference. If equipment sensitivity was always well known and defined, then we would have few, if any, doubts. In this perfect world, we would also know with a high degree of certainty that a voltage sag of a known amplitude and duration would have either no effect or a significant impact on equipment. Unfortunately, we seldom are privy to such information. Therefore, the possible effects of neutral-to-ground (N-G) voltage are often left up in the air.

When you measure N-G voltage, the measurement yields a simple voltage differential, which a voltage potential on either the neutral conductor or grounding conductor may create. Furthermore, this differential may be a simple by-product of neutral return current — or may even be part of a complex common-mode voltage signal. The effects of these conditions vary...

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My house was built in 2002. I just happened to notice that most of the outlets in the home measure 120v between the ground and nuetral. Is this normal ? If not what could be causing this and what should I do to fix this ?

Please advise.


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