Ground Neutral and Hot wires explained


Hey there guys. Paul here from TheEngineeringMindset.com. In this video, we’re going to
be looking at the difference between the hot, neutral and ground wires as well as the function of
each with some worked examples. This video is for homes in North America. If you are outside this region then you can still follow along
but your system will work and look a bit different, so
do check out our other videos. Remember, electricity is
dangerous and can be fatal. You should be qualified and competent to carry out any electrical work. Before we get into this video, there are three things
I need you to remember. Number one, electricity will only flow in a complete circuit. If you come into contact
with an electrical conductor, your body might complete the circuit. Number two is that
electricity always tries to return to its source and number three, electricity will take all available paths to complete a circuit but
it will take preference to a path with less
resistance and so more current is going to flow in that path. So we’re going to be looking at the hot, neutral and ground wires for a typical North American
residential electrical circuit. First we’ll see a really simple circuit to understand how it works, then we’re going to apply this knowledge to a complex residential installation. When we look at a simple
electrical circuit with just a battery and a lamp, we know that to turn the lamp on we need to connect both ends of the wires to the terminals of the battery. Once we connect these wires, the circuit is now complete
and electrons can flow from the negative through the lamp and then back to the positive terminal. So for the circuit to be complete, we need a wire to carry the
electrons from the power supply and over to the light. This wire is our hot wire, then we need to connect
another wire from the lamp and back to the battery for the electrons to get back to their power
supply or from their source, and this wire is our neutral wire. The hot wire carries electricity
from the power supply and then will take this over to the load. The neutral wire carries
the used electricity back to the power supply. If we look at a residential
electrical system in North America, then we
will find two hot wires a neutral wire and some ground wires. If you want to see in
detail how this all works then check out our video for that, links in the video description below. Now, imagine for a second,
the homes electrical system is connected to a battery
and we have just one hot wire and a neutral wire. And as we saw with the simple circuit, for the light to turn
on, we need a hot wire to the supply of the current to the load and we need the neutral wire to return the current to the source. Electricity therefore
flows through the hot, through the busbar and the circuit breaker
and into the light. It then travels back through the neutral and over to its electrical source. Now, of course homes are
not connected to a battery, they are connected to transformers. So we’re gonna replace the
battery with a transformer and there we go, we
have a complete circuit. The electricity in this circuit
is AC, alternating current, which is different from
the DC, direct current, which we saw with the battery. With DC, the electrons flow directly from A to B in only one direction, much like the flow of water down a river, but in our homes we have
AC, alternating current, which means the electrons
alternate their direction between forwards and backwards much like the tide of the sea. Now, in North America, we
have a split phase supply to most residential properties. So we have the two hot
wires and one neutral wire. We simply have two 120V coils
which are connected together in the transformer. The neutral is then
connected to the centre between the two coils. When we connect our multimeter between a hot and the neutral, then we’re going to get
a reading of around 120V, and we get the same
reading for the other one. That’s because we’re only
using half of the coil in the transformer. But then when we connect
between the two hots, we get 240V because we’re
using the full length of the transformer coil. Now, if you don’t have a multimeter, I highly encourage you to get one, links down below for which
one to get and from where. Now, if we have a load on
only one half of the coil and the load is, for example, 20Amps, then the hot wire will
carry 20Amps to the load and the neutral wire will carry
20Amps back to the source. You can measure the current in a cable using a current clamp meter. Again, links down below for
which one to get and from where. If you don’t know what
current or amps are, then check out our video
on electrical current, link to that in the video
description below also. Now, if we have another load
on our other half of the coil and the load is a different value, say for example just 15Amps,then
the neutral will only carry the difference between
these two values back to the transformer or back
to the electrical source. So in this case, one side we have 20Amps and the other side we have 15Amps, so the difference between
these is five amps. So the neutral will carry five amps. Where does the rest of this go? Well, it will pass
through the two hot wires. And this is what we have in most cases because there are multiple
circuits with different loads in the residential property. However, if we had a load on both coils and they’re of equal value,
say for example 15Amps each. Then there will be no current
flowing in the neutral wire. So where is it going? Well, it’s flowing back and
forth on the two hot wires between the load and the source. That’s because it’s AC,
alternating current, and the transformer is
centre tapped with a neutral. So while one half is moving forwards, the other half is moving backwards and the current will flow
into the other circuit instead of back via the neutral. Hopefully, that hasn’t
confused you too much. If it has, then don’t worry
about it too much for now, we’re gonna cover that
in a more advanced video. So the hot wires carry
the electrical current from the supply and over to the load and the neutral wires carry
the electrical current from the load and back to the supply. So what does the ground wire do? The ground wire, under
normal operating conditions, will not carry any electrical current. This wire will only
carry electrical current in the event of a ground fault. Hopefully, this wire will
otherwise never ever be used at all in its entire life. It’s just there for an emergency path for the electricity to get
back to the power source instead of it passing through you. The ground wire in most
cases is a bare copper wire, it’s uninsulated, but in
some cases it is covered with a green insulation. This wire has a very very low resistance so electricity will
prefer to travel along it because it’s easier and
can get back quicker. Now if we go back to the simple circuit with a battery and a lamp,
if we now run another wire and run this from the positive
terminal over to the lamp and we connect this to the
metal of the lamp holder, then this is effectively our ground wire. As you can see, it’s not being
used to carry electricity. If the hot wire touches the metal casing then the electricity will now flow through the ground wire instead. If the hot wire is connected
to both the neutral and the ground, then it will now flow through both wires back to the source. But as the ground wire
has less resistance, then more current will flow through it. When electricity finds a
way to leave its circuit and return to the source
through a different way than its neutral wire, this
is called a ground fault. Coming back to the house, the electricity flows through the hot wire and into the light and then
back through the neutral, but if the hot touches the metal casing, then it will instead flow
through the ground wire back to the panel, through the busbar and then back to the transformer
via the neutral wire. The ground wire has a very low resistance which causes a huge and
instantaneous increase in current which will trip the breaker. We therefore connect the
ground wires to anything that could potentially
become a potential path for electricity to leave its circuit, such as the metal pipes, the metal plates and the light switches and
the outlets of the boxes, we also need to run one to the outlets because often our
appliances are made of metal or they’re covered with a metal casing, the things like washing
machines and microwaves. When you look at a receptacle and plug, you’ll see that there is a hot terminal, a neutral terminal and a ground terminal. The casing of something
like a washing machine is connected to a ground wire in the lead which goes to the plug,
through the receptacle and back to the panel to save
you from an electric shock. Now, let’s say you’re
outside with no shoes on and the ground or the soil is moist. If you touch a hot wire, you
could complete the circuit and current may pass through
you to get back to the supply. In this case, the resistance
is going to be very high. So the current might not be high enough to automatically flip the
breaker and cut the power. This will likely lead
to the person’s death. Luckily we have the GFCI
receptacle or the GFCI breaker. GFCI stands for Ground
Fault Circuit Interrupter. We’re gonna look at a
circuit breaker version but essentially they’re
gonna work the same. This GFCI breaker is going to be connected to both the hot and the
neutral of the circuit, and so we can monitor the wires and ensure that the current running in
the hot wire of the circuit is equal to the current running in the neutral wire of the circuit. If the current is not
equal in these two wires, then it’s clearly flowing
back to the source via another route, we
then have a ground fault. The breaker will realize
this and very quickly and automatically flip to cut the power and kill the circuit. Connected to the main panel, we will find a thick copper wire which leads out to a ground rod. A ground rod is buried into the ground outside near the property. This rod is not used for ground faults. Its purpose is to dissipate
static electricity and external high voltages
like lightning strikes. There is also a ground rod
connected to the neutral at the transformer. Many people think that
during a ground fault electricity flows through the ground rod and into the earth. Now, remember electricity tries
to get back to its source. It doesn’t just go into the earth. Unless there is a ground
rod at the transformer, then there is a potential
path for the electricity to get back to the source,
but this path will have a very high resistance for impedance. And as we know, electricity
will take preference over the path with the least resistance. So as we already have a very
low resistance ground wire which provides a path
directly back to the source, the ground fault is going
to take this route instead. When it comes to lightning, the source of lightning
is essentially the earth. So lightning is always trying
to get back to its source which is the earth. If lightning strikes the utility cables, it will flow along the wires
to get to the ground rods of both the transformer
and also your main panel. It’s gonna do this to try
and get back into the earth. If it wasn’t for this,
then it’s going to blow all our circuits then it’s
gonna cause house fires. Now, if the hot wire
came into direct contact with the ground rod, then
electricity will flow through the soil, back to the transformer, but the resistance is very high
so the current will be low. This means the circuit breaker will not likely detect the fault and the circuit breaker
will not automatically flip to cut the power. Okay guys, that’s it for this video but to continue learning, then click on one of
the videos onscreen now and I’ll catch you there
for the next lesson. Don’t forget to follow us on
Facebook, Twitter, Instagram, as well as TheEngineeringMindset.com.

66 comments on “Ground Neutral and Hot wires explained”

  1. The Engineering Mindset says:

    ⚠️ Found this video super useful? Buy Paul a coffee to say thanks: ☕

    PayPal: https://www.paypal.me/TheEngineerinMindset

  2. Hector Cardenas says:

    In Mexico we also use the same North American Electric Code, and of course our own NOM code.

  3. Deplorable B.R. says:

    I watched a YT video…ready to go!! 220, 221 whatever it takes!

  4. Andrew Hardcastle says:

    As always a great video , just. A tad too fast for my aging non electrical brain , I’ll rewatch thanks

  5. Tn Floose says:

    I thought the bare wire was neutral

  6. Tony Williams says:

    Fantastic video. Only thing that would have made it more helpful would be directional arrows rather than just rectangles on the current paths. That way, when the video is paused to digest, you can still identify the current directions. Thanks for the video.

  7. DO YOU WANT SLI??? says:

    You didn't explain the difference between neutral and hot though? Why are they not the same? They are interchangable in many cases but supposedly not in some?

  8. bob V says:

    Very useful, but I did not like the mention of Impedance, (9:53) it can be correct if you did not use it with the word resistance which are two different things. As resistance is for DC power as impedance is for AC circuits only. Both have a type of resistance in essence, however a pure resistor will have no induction reaction and will work well in both types of circuits. However, a coil or transformer will not have the same affect as it's ( resistance—INDUCTION ) will change with frequency………….XL or Impedance = 6.284 X Frequency X Inductance In Henry's. OR XL = 2πFL.
    Also do not ever believe a ground fault interrupter will keep you safe. Example…. If by some chance you are completely insulated from ground and you make contact with both the hot and natural wires the GFCI will not notice a change in flow ( in VS out ) and you will be electrocuted. Since the GFCI is looking for a change in out put verse return no change will be detected. The GFCI will only detect if the output AND return are different which means that some of the missing electricity is going to ground and not returning to the GFCI circuit. Same is true for and isolation transformer.

  9. Jan Nielsen says:

    Thanks for you demonstration. However, I have 2 questions and would appreciate an explanation.

    Question 1: You said (10:37), if the hot wire is connected directly to the ground rod, it will not trip the breaker because the resistance of the path to the transformer neutral is too high. However (8:16), if a man steps on the grass and touches the hot wire, it will trip the breaker. Please explain why in the first case the breaker does not trip, but in the second it will. In the second case, the resistance should be greater compared to the hot wire connected directly to the ground wire.

    Question 2: If the wire connecting the fuse box to the ground rod fails, will all the GFCI breakers fail to trip a ground fault?

  10. Paul FUN says:

    I still don't get it.

  11. John says:

    Really liked the explanation of different Amp loads on each side of coil and that difference feeds back on the Neutral to source. If loads are equal, then nothing fed back on Neutral. I didn't know that! :thumbsup:

  12. dave miller says:

    Why does he show power coming from the – neg pole of the battery and to the + pos pole. Should be the other way around unless I am missing something. Also the +pos wire should be red and the – neg wire should be black when dealing with DC current. At least in the US.

  13. Gary D. Brewer says:

    Don't ask me how I got here or why I couldn't stop watching. I'm still trying to figure that out.

  14. Gerald Foster says:

    You are talking about “hole theory” vs “electron theory.” Electrons flow from + to -. Holes flow from -to +, it can be confusing. I adhere to the electron theory. Makes lots more sense.

  15. Jamal Baker says:

    I always thought Hot meant Sexy wire. I stand corrected.

  16. Aaron King says:

    Norf America…

  17. Jordan Rodrigues says:

    If there's a difference between the neutral and ground wires, the grounding wire will usually be smaller and less conductive than the neutral. This is allowed because the grounding wire isn't intended to carry current, so it needs less ampacity. (In many cases. Consult the code for details.)

    I believe the better way to describe the difference between them is to say that the neutral wire belongs to the energized system – everything connected to the transformer for the purpose of carrying current and doing electrical work. The ground wire does not belong to the energized system. It shouldn't carry current and should be insulated from every energized wire – including the neutral wire.

    If the neutral wire breaks, or has a bad connection, or is simply part of a long circuit, distant points of the neutral wire will have a meaningful voltage difference compared to the grounding wire. This is analogous to a drain backing up with water. The safest way to handle this situation is to insulate the neutral from anything that people could touch. A ground-neutral connection will allow current to find additional paths back to the transformer, including paths through people. These stray paths are difficult to predict.

    You could have appliance A (a space heater) generating a lot of neutral current. Appliance B on the same circuit has a neutral-ground leak, which causes a shock hazard between appliance C and appliance D. The best way to prevent this is to use GFCI breakers (which will trip the circuit that supplies A and B). Troubleshooting can be tricky, keeping records helps.

    The neutral wire is intentionally grounded at one point because this allows overcurrent and GFCI sensors to detect and de-energize damaged equipment more quickly and reliably. This won't complete a circuit unless a second ground-neutral connection is made – so don't do that. Treat the neutral wire as part of the live system and don't ground it unless the code tells you to.

  18. jsamples says:

    Why do you have the RED wire as negative when everyone else uses RED to indicate POSITIVE ? A car battery is a good example.
    Yes its DC, but so is your AA battery.

  19. mr nothing says:

    Excellent explanation and also very well read
    Just a little bit slower please
    The goal is to make people understand and process
    There is too much pausing going on here

    Keep up the good work

  20. Jovet says:

    Really helpful video. Nice visualizations! The only thing I don't like is around 1:47 when you're using terminology of "hot" and "neutral" with regards to a battery source. Since you later touch on the difference between AC and DC, and how the center-tapped neutral works, this seems particularly egregious.

  21. Giulio Costantini says:

    i am european, i don't get why americans connect the ground wire on the neutral and why 2 phase?
    it's a waste of copper, you have to bring 3 cable from the transformer to the house and the lower voltage mean you have to use bigger wires for the same power.
    also why americans use rigid wire? it's a nightmare to work with rigid wire.

  22. Mario Sanchez says:

    Just 1 question, So if electricity its trying to get back to its source, why when 2 wires hot and neutral touches together starts shorting out or cause a fire if is only trying to return to its source it should not make a short or the wires shouldn't start melting down.

    I dont know maybe im not understanding it?

  23. M says:

    Is there any difference between the construction of a hot and neutral wire? Are they the exact same wire simply with different colored sheathing?

  24. No Future Productions says:

    This was explained in the clearest manner that I've ever come across.
    I wish my college professor, back in the day, explained it this way. He was ready to retire, and we were the last class he taught.
    This was one of those concepts that had eluded me for some reason; for quite awhile. I had an easier time with understanding calculus than this one thing.

  25. mutangana emmanuel says:

    I didn’t quite understand where the current going back to the source is zero when u have two loads. If electricity is always trying to go back to the source, how come does it stay circulating between loads and hot wires. Is there mathematical or law of physics that explains that.Anyone who can help me will be much appreciated

  26. Jarrod C says:

    Ok so you never really explained how the source of the electricity is the earth. I would have liked a better explanation of that. Please and thank you

  27. rockymnt hodad says:

    respecting your 'simple circuit' example, you show – neg terminal of bat as the 'hot' … I have always been taught that – neg was ground and + red was the hot ? (in D/C type circuit). What am I misunderstanding in your example?

  28. Khalid Rao says:

    A very good video enjoyed. Thanks.

  29. Devin Doiron says:

    5:03 is that an example.of how 3 phase works ? 120 120 120 each out of phase, casuing 0 not needing a neutral ?

  30. G Dunken says:

    After high school, I resisted the thought of doing engineering. But currently, I am a graduated electrical engineer. I think these videos are very powerful for anyone having difficulty on these topics.

  31. John William Aguon Cruz says:

    Awesome!!!

  32. HENRY BARTLETT says:

    I am assuming that there are no additional connections in the pump motor junction box?

  33. Robert Beauchamp says:

    I always though that ground faults went to the grounding rod. My life is a lie.

  34. DADAROBOTO says:

    Wish there was a Part Two to this to explain why the Neutral and ground are separated in Sub Panels. And how the ground rods work on them if the are on a detached building as well.

  35. Will Pack says:

    lol. that neutral will shock the shit out of you just as bad as a hot wire. Most people don't know this. Thanks for explaining why.

  36. Eabbat A says:

    These are very good videos, I highly recommend them for simplicity in understanding electricity. Keep in mind that ground rods are used mainly east side of US and in the western states with rock they do not use ground rods but use a ufer ground in which Florida is now requiring them with the Delta ground. A ufer ground is copper wire cadweld to rebar 20' in length and is encased in concrete, i.e. footers, of course this is commercial and not residential.

  37. Northern Hills Curb Appeal says:

    Thanks for the video. I see a lot of knowledgeable people in the comments as well so I’d like to ask about a problem I’m having at the moment.

    -Water got into a non GFCI outlet; tripped a breaker.
    -Let area dry; replaced with new GFCI outlet, reset breaker. Outlets and lights still not working.
    -Tested all breakers; all output 120V.
    -Checked all GFCI outlets in home for reset.
    -Checked voltage at non functioning outlets; 120V to top outlet in two separate locations, both bottom outlets have no voltage. Third location has no power.
    -Plugged fan into top outlet, will not power on. GFCI outlet is dead.

    Please help. Thanks in advance.

  38. arctic_dan says:

    Very informative. I never knew DC current flowed from – to +. My life is a lie. Does that mean on vehicle battery's the power is actually coming from the – or did the manufacturer reverse the – and + signs…

  39. Josepher Brown says:

    💪💪💪

  40. Mathew Ostovich says:

    Pretty conventional but good explenation.

  41. FRENZYPIRHANA13 says:

    If the hot line faulted to ground before it reached the panel box, would the fault current flow to the grounding rod of the transformer.

  42. R.D Nutz says:

    Use a pigtail on the neutral so ya wont have an open neutral?!? 🤔

  43. Willy Freebody III says:

    5:03 – 5:13 if the neutral has no difference to return would that send 240 volts through you're loads

  44. groove jet says:

    this conventional current i just dont get? How can i understand it better? If current flows from negative , through circuit to positive ? Why is this protrayed to frow from positive to negative? Is this just for dc circuits?

  45. Recoo jones says:

    OSHA certified

  46. Svyatoslav Russkiy says:

    These videos are very clear to understand, thank you.

  47. Ken Haley says:

    This is great, except I have one question: At 5:45, the ground wire is connected to the load and panel exactly the same way as the neutral wire, right? So, why doesn't current flow through the ground wire as well as the neutral wire back to the panel? Both wires have approximately the same resistance; therefore, wouldn't they both carry the current?

  48. seema sharma says:

    Awesome channel

  49. longbeachboy57 says:

    You lost me…

  50. Brian Walden says:

    Useful information for sure. Only thing that I wish would be different is using a direct current (battery) as an example for a power source to simulate alternate current diagrams

  51. Tom Garbo says:

    No such thing in USA or NEC as a nuetral. Now called grounded conductor. Yep stupid to change such a much used term for last hundred years.

  52. Tom Garbo says:

    3 wires from ultility company not split phase. Called 3 wire edison system. An example of split phase is a single phase capacitor start motor. The start winding is ouf of phase with motor run winding.

  53. Surging Circuits says:

    Best explanation I've seen. TY!

  54. Hooty Poot says:

    No why applied to the knowledge ,

  55. Impractical will says:

    Why dont i get shock from a neutral wire in a ac power supply

  56. Stanley Spadowski says:

    Great video! It raised 2 questions in my feeble head: 1) Why aren't ground wires insulated? Seems like that could potentially make them useless should they be in contact with something grounded. 2) So what happens when a hot touches a ground? You mentioned it wouldn't trip the breaker, but didn't mention what would happen.

  57. Egon Samson says:

    Thank you for this…. This was better then my apprenticeship classes…. I wish they explained it like you and had animated pictures like yours

  58. Egon Samson says:

    After 2 years taking IBEW apprenticeship classes. Was still unclear about much of this…. I can't tell you how much I appreciate the way you've explained this….

  59. Colorado Cyber says:

    Now I know… it's the ground's fault.

  60. Tejas Dhamnaskar says:

    1:57 neutral wire to positive side and hot wire to negative side ??? Why and how

  61. John Jacob JinglehimerSchmidt says:

    Ok having watched this many many times some ??'s still persist.

    1. So home hook ups are NOT multiple phase? I always thought that special dryer plug meant more than one phase.
    2. So when you hook up a house, what determines the amp service to your property? Is it just the size of the main breaker in the house or meter? What's the max amperage that can be connected?

    i ask cause I'm beginning to feel the need to have my own house again. But I'm looking for property to also have a med shed/shop possibly. Just wondering would I increase the overall amperage to the house and then send xx amperage service to the shed? Yes I realize could just install new service / meter on the shed…. possibly

  62. John Gallo says:

    How do I know the difference between a hot and Neutral in my light switch box?

  63. Sawkarenpoe says:

    Can you please also explain the wiresize and its rated current?

  64. Agent Anderson says:

    the premise as i understand it is that in a quantum binary electron spin system, if anything tries to link on to a pathway or channel to tap a line? if this situation is attempted by say a spy , then do to the nature of the security there is a disruption in the electron spin causing a block in the whole transmission media? if electron fail to flow in a measured way, the flow for electrons anomaly is detected and stops like a GFIC? true or false class?

  65. Giotinez says:

    I thought the hot wire was the one mark with the + .
    Nobody can explain neat and clear like you.
    Thanks

  66. Luis Hernandez says:

    So ground is basically an emergency neutral… thanks man

  67. John Nevin says:

    Excellent video you have produced, Thank you

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