Your video presentations are simply the BEST I have ever watched. So we'll explained and presented. As an industrial/commercial electrician for over 40 years, I really enjoy watching your stuff! It's always a great refresher for me. Thank you, Dave, for sharing your knowledge and insight!
Thank you Dave. I notice your little paper in the corner. I’m currently working on starting a business called SDG Electric ;). Appreciate everything you do sir!
THANK YOU! I was looking for an explanation of exactly HOW current can possibly flow back to the source through the second hot leg on a multi wire circuit, from an electrical theory point of view. You explained it very simply and eloquently with your “trading post“ analogy. Thank you, sir! This was very, very helpful!
16:35 Thank you. Now i understand why, sometimes, the engineers asked for a double wired neutral in transformers. I learned more in 2h watching your explainations, than i did in 20 years . I suggest you do some videos about motors.
Thanks for your vote of confidence, and thanks for engaging with the other viewer. I put a link to my new "open neutral" video in the responses below if you're interested.
Great videos, Dave. A suggestion... a set of videos on Grounding and Bonding would be super helpful. I understand the concepts, but I don't understand how the grounding and bonding topics are organized in the NEC and I spend a lot of time flipping pages to be sure.
@davegordon6819 You were an instructor of mine at the JATC in 46. If I'm pulling 3 hots, neutral and a ground to a 100 amp MLO subpanel that serves a majority of linear loads that would be considered 3 CCC correct? #1 XHHW Aluminum.
I have a 3 phase solar inverter combiner panel the load is balanced on all 3 phases. I don’t even think the neutral Carry’s current would I have to count it ?
Great video! I don’t get to work with a lot of wye systems. I have seen a 10 awg neutral on a shared system with non linear loads. Is this a code article requirement or just a good work practice?
Hey Dave! I want to solve my problem: This is my step up transformer which is used as an inverter from DC to AC, when this transformer outputs voltage my both wires are phases and no neutral, so how to get a neutral wire from them as most sine wave inverters create a neutral phase.
Great video! So am I correct in saying in most commercial applications i.e. office buildings, schools, medical offices, etc. we should be counting the neutral due to 310.15(E)(3)?
Is it not the case that basically all home setups are unbalanced? I mean, no one is going through their homes and adding the amps up on each circuit to ensure they're balanced. So in the neutral is probably always carrying current, right?
In individual circuits (1 hot paired with 1 neutral) the neutral carries the same amperage as the hot and is always counted as a current carrying conductor.
Is there a situation where the neutral wire needs to be larger gauge than the "hot" wires because it has the potential of carrying more amps than the "hot" wires?
when using a grounded centre tap voltage divider you get two phases 180 degrees out of phase, this is WHY it is called the Neutral, it is at the neutral point, 0V. so when current is being drawn on both hots, one is in the positive cycle and the other is in the negative cycle. being 180 degrees apart, where these waves meet on the neutral they cancel each other out proportionally. it is the ground on the neutral that is important, that is what keeps it at half voltage 120v on a 240v supply, if you lose the neutral point you just get 240V as at that point there is no voltage divider, if yo lose the ground / earth at the voltage divider you get a floating Neutral, which will move up and down the wave giving varying voltage depending on the loads on each side of the voltage divider. a higher current draw (higher resistance) will push the neutral up the wave giving a lower voltage to that side and a higher voltage to the other side up to the full wave and full voltage.
If the neutral is still connected but loose, it could create a high-resistance point in the circuit that would not only get hotter than it should, but could create voltage drop due to the high-resistance point being in series with rest of the circuit. However, if you are asking what happens if it gets disconnected, then I'll refer you to a video I just made that addresses that exact issue of an "open neutral": ruclips.net/video/LJvyb_WujZg/видео.html
For the single phase drawing at the top, where you had two separate multi-wire circuits, would it introduce the potential for any weirdness if the two non-shared neutrals were accidentally swapped?
Good question. If the two neutrals were swapped on the right side of the top diagram it could create a big problem. You would then have the lower black wire sharing a neutral with the upper black wire. The result would be that that neutral would carry the addition of the two black wires - meaning that if each was carrying 20 amps, the neutral would be carrying 40 amps. They would not cancel each other out. It would be like sharing a neutral between two wires from the same leg (bus) in a residential panel. This is why when we are working with 120/240 V single-phase panels we need to make sure that if we share neutrals, we share them between one wire from one bus and one wire from the other bus. Likewise, in other facilities where we run more than one multiwire branch circuit within the same conduit, we must identify which neutrals go with which phase conductors [see NEC 200.4(B)]. Alternately, if you tied the two neutrals together, you could entertain similar issues depending on how much current is flowing on each hot conductor... I plan, at some point, to make videos that focus on current flow with the various systems and point out these sorts of problems.
*raises hand* If you take 2 of the hots in a 3 phase service to power a 1 phase device, wouldn't the voltage be irregular since the waves and troughs of the AC current aren't oppsite and balanced? Apprentice here.
Assuming a wye configuration - peak to peak Voltage across 2 phases is 2(cos(30)) of p2p-V on and single phase. So 208 on a 120 Wye. But it's still a regular sine wine. (Any addition of sine waves at the same frequency is another sine wave on that frequency.
The first system is slightly wrong i thought because the coils are wound in opposite direction, so line to line is 180 out of phase. Hence the 'split'. Also tell them it's a voltage source not current source if any load asks...
“Counting the individual neutral, with one hot.” I get the electrical theory, but it’s not in writing in the code book. How come ? They should add a #4 to clarify that even though is common sense, it’s not mandated in code in specific writing
I have a tricky multiple choice question, hopefully someone with more knowledge can help me out A White/grey wire in a feeder circuit ________: A)Be bonded or have a circuit breaker B)Is the largest wire in that circuit C)Should not have a voltage to ground My notes: On the main panel, neutral is connected to the bar that is bonded with the panel, the green grounding wire is also connected to the same bar. (so does that mean the answer is A?) In the sub panel, the neutral wire is connected to the neutral bar which is isolated from the metal box with plastic between them, the Green grounding wire is separated and is connected to its own bar that is bonded to the sub panel box. In the circuit that this question applies to, --------- “The neutral wire is going to be sized larger than the Green grounding wire” (But that doesn’t mean it’s the LARGEST in the circuit right? Because the two hot wire could be the same size) --------"The neutral should have no potential difference(voltage) to the ground" (does that mean the answer is C?) (But that doesn’t mean it’s the LARGEST in the circuit right? Because the two hot wire could be the same size)
Quite interesting, as european i wasnt sure how US 120/240V thing works but logical ofc. Fault with open neutral would cause all kinds of shenanigans in the the system then whereas in EU system it would fully turn off the circuit. I wonder if it is a problem with devices getting destroyed etc with that kind of fault.
Three phase is common in Europe and in it the results are similar to what in the US split phase. On the other hand in the UK style single phase broken neutral puts full 240 V to equipment cases. In split phase and three phase it can be smaller than the full mains.
Dave... Why do you call power carried by a conductor "heat". I 'think' I know why. But can you explain your use of that word in the context of this lecture, please? (Notice, fellow viewers, that I ask DAVE... and not YOU... for Dave's explanation.)
hello, Dave i have a question and if you have a time answer me please , first of all thanks for every efforts that you give us so , In a single-phase transformer input, one wire getting entry as live, another as neutral. But what would be in case of its output? In output, which-wire would be phase, and which-one would be neutral? pasteboard.co/dlGFszYF6Iai.png
The system is AC, any one can be hot or neutral. but usually ground/bond is connected to one of the wire which is than identified as neutral. Let’s wait for Dave to comment further
Dave, you are an exceptional teacher. I appreciate, so much, your organized and sequential manner in which you teach. You rock!
This is probably the most thorough explanation of shared neutrals I've seen - well done.
Your video presentations are simply the BEST I have ever watched. So we'll explained and presented.
As an industrial/commercial electrician for over 40 years, I really enjoy watching your stuff! It's always a great refresher for me.
Thank you, Dave, for sharing your knowledge and insight!
This guy actually makes learning this complex stuff enjoyable.🤔⚡
Thank you Dave. I notice your little paper in the corner. I’m currently working on starting a business called SDG Electric ;). Appreciate everything you do sir!
Best teacher ever, and above all correct!
Dave i really injoy the way you break it down, it really makes sense, thanks bro!
THANK YOU! I was looking for an explanation of exactly HOW current can possibly flow back to the source through the second hot leg on a multi wire circuit, from an electrical theory point of view. You explained it very simply and eloquently with your “trading post“ analogy. Thank you, sir! This was very, very helpful!
Clear and concise explainations of both the theory and the NEC. Thank you.
16:35
Thank you. Now i understand why, sometimes, the engineers asked for a double wired neutral in transformers.
I learned more in 2h watching your explainations, than i did in 20 years .
I suggest you do some videos about motors.
Soli Deo Gloria for this man’s videos.
DAVE your a BEAST! Thanks for these videos!🙏
“Oop, keep my thumb down.” A great educator & can bring a smile to my face👍
Im so glad i subscribed to your channel. Your videos have helped me understand a bit more. Thank you!
That was great! Wish you had been my code teacher when I was an apprentice!
Great info, Dave. Thank you.
Thanks for continuing to post, Dave. Your explanations are remarkable.
Thanks for your vote of confidence, and thanks for engaging with the other viewer. I put a link to my new "open neutral" video in the responses below if you're interested.
Fantastic video. It makes total sense now. Plus a bonus for having the Soli Deo Gloria posted.
Thanks brother. I am thankful for God's mercy to me and may He help us both to use what He has given us for His glory.
Thank you very much.
One of the best electrical videos I've seen (hoping info is correct) but thanks
Thank you Dave.
You make it very easy to understand.
again....just a great Teacher. Thanks!
Clearly and easy understand. 👍
excellent job sir ! well explained and much appreciated !
Very well explained!!
Great explanation! Thank you
Excellent lecture. So well explained. Cannot think of any questions after this
Dave is the best! 🧑🏻🏫
Great videos, Dave. A suggestion... a set of videos on Grounding and Bonding would be super helpful. I understand the concepts, but I don't understand how the grounding and bonding topics are organized in the NEC and I spend a lot of time flipping pages to be sure.
Great explanation
Thanks for the awesome and useful class!
Excellent explanation!
I like how Dave puts the code section next to his pictures
Excellent video thank you so much
the best explanation!
Thanks...I really enjoying
@davegordon6819
You were an instructor of mine at the JATC in 46. If I'm pulling 3 hots, neutral and a ground to a 100 amp MLO subpanel that serves a majority of linear loads that would be considered 3 CCC correct? #1 XHHW Aluminum.
What is the wire that runs to neutral and back to the electric company? And would that effect a transformer if it was faulty?
You are the best.
I have a 3 phase solar inverter combiner panel the load is balanced on all 3 phases. I don’t even think the neutral Carry’s current would I have to count it ?
At 6:40 I was like….”ohhhhh duh” and it all finally made sense. 🙃
Nicely done
Where have you been all my life!
Fascinating
Great video! I don’t get to work with a lot of wye systems. I have seen a 10 awg neutral on a shared system with non linear loads. Is this a code article requirement or just a good work practice?
Hey Dave! I want to solve my problem:
This is my step up transformer which is used as an inverter from DC to AC, when this transformer outputs voltage my both wires are phases and no neutral, so how to get a neutral wire from them as most sine wave inverters create a neutral phase.
Very informative video.
Great video! So am I correct in saying in most commercial applications i.e. office buildings, schools, medical offices, etc. we should be counting the neutral due to 310.15(E)(3)?
Is it not the case that basically all home setups are unbalanced? I mean, no one is going through their homes and adding the amps up on each circuit to ensure they're balanced. So in the neutral is probably always carrying current, right?
In individual circuits (1 hot paired with 1 neutral) the neutral carries the same amperage as the hot and is always counted as a current carrying conductor.
Very good. Does anyone know if Dave is a professor at a nationally recognized University?
Thank you prof.
Dudes a correction factor ninja….😎
Is there a situation where the neutral wire needs to be larger gauge than the "hot" wires because it has the potential of carrying more amps than the "hot" wires?
No
when using a grounded centre tap voltage divider you get two phases 180 degrees out of phase, this is WHY it is called the Neutral, it is at the neutral point, 0V. so when current is being drawn on both hots, one is in the positive cycle and the other is in the negative cycle. being 180 degrees apart, where these waves meet on the neutral they cancel each other out proportionally.
it is the ground on the neutral that is important, that is what keeps it at half voltage 120v on a 240v supply, if you lose the neutral point you just get 240V as at that point there is no voltage divider, if yo lose the ground / earth at the voltage divider you get a floating Neutral, which will move up and down the wave giving varying voltage depending on the loads on each side of the voltage divider. a higher current draw (higher resistance) will push the neutral up the wave giving a lower voltage to that side and a higher voltage to the other side up to the full wave and full voltage.
Would the neutral count if it were a 4-wire, 3 phase wye connected system with only 1 phase conductor and the neutral?
Every time you have a single phase a neutral Carry the current back so that group is counted as 2 wires
whta does it mean when you say "add heat" ?
Why doesn't the voltage increase if the waves are out of phase?
Hello mrs Dav.. so if the main neutral wire loose what is going to happen to the system?
If the neutral is still connected but loose, it could create a high-resistance point in the circuit that would not only get hotter than it should, but could create voltage drop due to the high-resistance point being in series with rest of the circuit.
However, if you are asking what happens if it gets disconnected, then I'll refer you to a video I just made that addresses that exact issue of an "open neutral": ruclips.net/video/LJvyb_WujZg/видео.html
Thk you very much mrs Dave
For the single phase drawing at the top, where you had two separate multi-wire circuits, would it introduce the potential for any weirdness if the two non-shared neutrals were accidentally swapped?
Good question. If the two neutrals were swapped on the right side of the top diagram it could create a big problem. You would then have the lower black wire sharing a neutral with the upper black wire. The result would be that that neutral would carry the addition of the two black wires - meaning that if each was carrying 20 amps, the neutral would be carrying 40 amps. They would not cancel each other out. It would be like sharing a neutral between two wires from the same leg (bus) in a residential panel.
This is why when we are working with 120/240 V single-phase panels we need to make sure that if we share neutrals, we share them between one wire from one bus and one wire from the other bus. Likewise, in other facilities where we run more than one multiwire branch circuit within the same conduit, we must identify which neutrals go with which phase conductors [see NEC 200.4(B)].
Alternately, if you tied the two neutrals together, you could entertain similar issues depending on how much current is flowing on each hot conductor...
I plan, at some point, to make videos that focus on current flow with the various systems and point out these sorts of problems.
I remember something about neutral ampacity rating at 70% of phase voltage
*raises hand* If you take 2 of the hots in a 3 phase service to power a 1 phase device, wouldn't the voltage be irregular since the waves and troughs of the AC current aren't oppsite and balanced? Apprentice here.
Assuming a wye configuration - peak to peak Voltage across 2 phases is 2(cos(30)) of p2p-V on and single phase. So 208 on a 120 Wye. But it's still a regular sine wine. (Any addition of sine waves at the same frequency is another sine wave on that frequency.
Power goes in and out both conductors. It's a perfect sine wave at whatever voltage the two are at line to line.
Where does the neutral originate
The first system is slightly wrong i thought because the coils are wound in opposite direction, so line to line is 180 out of phase. Hence the 'split'. Also tell them it's a voltage source not current source if any load asks...
What song is this?
so clear, tnx
🎯
I like Dave!
“Counting the individual neutral, with one hot.” I get the electrical theory, but it’s not in writing in the code book. How come ? They should add a #4 to clarify that even though is common sense, it’s not mandated in code in specific writing
Excellent video.
JW - LU #613
Yessss
Thank you sir
I have a tricky multiple choice question, hopefully someone with more knowledge can help me out
A White/grey wire in a feeder circuit ________:
A)Be bonded or have a circuit breaker
B)Is the largest wire in that circuit
C)Should not have a voltage to ground
My notes:
On the main panel, neutral is connected to the bar that is bonded with the panel, the green grounding wire is also connected to the same bar. (so does that mean the answer is A?)
In the sub panel, the neutral wire is connected to the neutral bar which is isolated from the metal box with plastic between them, the Green grounding wire is separated and is connected to its own bar that is bonded to the sub panel box.
In the circuit that this question applies to,
--------- “The neutral wire is going to be sized larger than the Green grounding wire”
(But that doesn’t mean it’s the LARGEST in the circuit right? Because the two hot wire could be the same size)
--------"The neutral should have no potential difference(voltage) to the ground" (does that mean the answer is C?)
(But that doesn’t mean it’s the LARGEST in the circuit right? Because the two hot wire could be the same size)
hey brother, did you find the answer? I want to know as well
May Allah bless u.❤
Hi Dave, my husband has some questions and wanted to know if you do one on one video calls plz let me know! Thank you!!
Quite interesting, as european i wasnt sure how US 120/240V thing works but logical ofc. Fault with open neutral would cause all kinds of shenanigans in the the system then whereas in EU system it would fully turn off the circuit. I wonder if it is a problem with devices getting destroyed etc with that kind of fault.
Three phase is common in Europe and in it the results are similar to what in the US split phase. On the other hand in the UK style single phase broken neutral puts full 240 V to equipment cases. In split phase and three phase it can be smaller than the full mains.
I dont see a 310.15(e)
Balanced load, don't use a neutral. Unbalanced load, use a neutral.
Dave... Why do you call power carried by a conductor "heat". I 'think' I know why. But can you explain your use of that word in the context of this lecture, please?
(Notice, fellow viewers, that I ask DAVE... and not YOU... for Dave's explanation.)
What country is this?
Remove the earth ground. Then what you say is true.
There are no harmonic you need flux
hello, Dave i have a question and if you have a time answer me please , first of all thanks for every efforts that you give us
so , In a single-phase transformer input, one wire getting entry as live, another as neutral. But what would be in case of its output? In output, which-wire would be phase, and which-one would be neutral?
pasteboard.co/dlGFszYF6Iai.png
The system is AC, any one can be hot or neutral. but usually ground/bond is connected to one of the wire which is than identified as neutral. Let’s wait for Dave to comment further