I was one of those guys installing all those single and 3 phase 3 and 4 wire networked circuits in Chicagoland for years. The danger was understood by professionals and accepted at the time. This was before homeowners were doing their own wiring repair with little knowledge of these systems. All wiring in our area, residential and commercial, was in metal conduit per local codes, and it was all about saving wire and reducing pipe size. With the introduction of harmonic loads generated by computers, something a normal meter couldn't see, overloaded neutrals bacame prominant and enlarging the neutral became the recommendation. Shortly after, the idea of handle ties came into being to reduce the safety hazard. In the romex world there was a lot less of this issue but it could still be found. You always had to be on guard when troubleshooting these MWBC's live as you could easily fry something on either circuit by simply pulling wires or devices out from a box and inadvertently having a wire come loose. You knew you were trouble when all the lights got exremely bright or you smelled fried electronics! All electricians need to have this knowledge in their arsenal whenever doing any troubleshooting. I'm glad to see you explain this phenomenon so well.
This was super interesting. A few years ago my family's old farmhouse lost the neutral line from the street and we saw all of that wonkiness on different circuits in the house. It took far too long to figure out what had happened since we hadn't "lost" power and no breakers were tripped. While it eventually was diagnosed and repaired, I didn't understand until now why we still had some power, but obviously not as it was supposed to be.
Many commercial buildings even call for shared neutrals as a money saving measure. Then there is the whole part of derating neutrals as well. Excellent explanation!!
About 10years ago I had a bad neutral connection at the service coming into my shop .Like you say a lot of bad stuff happened the red seal electrician from the electric company came out took a look at what was happening in the shop and said its not us its a problem inside your building and left .I work on dc electrics not read seal in AC work ,in 35 min I found it at the pole ,told the electric company they said in order for them to come back out I would have to get a certified electrician to inspect my shop a make an official report to them .screw that I fixed it myself .Side note they added 190$ to my monthly bill for the service call .You either pay or they cut your power .what a world you pay for some one else's incompetence By the way that was a fantastic and informative video. Keep up the good work.
I would like to add that at 6:45, the reason the sum of the currents adds up and goes back on the neutral is that the circuit is now wired in parallel, as they are on the same leg of the panel. So basically, steven is illustrating the principles of series vs. Parallel where current adds up but voltage stays the same (when wired in parallel) but in series voltage changes while current is the same. Brilliant explanation by the way, Master electrician in Boston
Your videos are seriously fantastic for the curious mind. Every time I watch something that you create, I'm left having learned something valuable. Thank you .
There is an inspection channel (maybe Morgan something?) with several light bulbs on a board and they demonstrate the imbalance that can occur with an open neutral. It's a great demo.
Resistance in a series circuit is additive, current is the same through all resistances, and voltage drops across resistors is the sum of the voltage source.
Ok. I get it now. Thank you for the excellent explanation. I will continue to NOT use multi wire circuits and to rewire those that do find in the wild.
GREAT JOB explaining in depth HOW it actually works, Thanks Steven, just one day Im gona be a good electrician like Steven..JUST MAYBE..LOL..U THA MAN 💪
10 years ago I had to move into a double wide mobile home. I was there for about 8 months. About 7 months in, I came home one day and flipped on the light switch in the kitchen and the bulb went super bright and blew out. The fridge was out, and the microwave would not work. The other half of the mobile home and all the lights worked normal including the tv. I called out an electrician and he figured it out in about 30 seconds. The grounding electrode conductor was corroded and the panel had no ground any longer. Half the trailer was 220 and the other half was still 120 he said because of the way they wired mobile homes back then. It was built in the 1970’s. He cleaned every conductor end in the entire panel and put it all back together. I replaced a fuse on the fridge and threw out the microwave.
I used to run multi wire branch circuits about 20 Years ago we ran conduit everywhere so it was easy to do harder to Do it nowadays with all the code requirements it was called a network circuit
@@kcb5336 thanks. The vertical camera is because my primary page is tik Tok and IG 136k followers and 61k followers. Mostly on UA-cam I am just filming shorts or reposting my stuff form other pages. When I try to video horizonal my camera is now on the edge but my eye are still looking into he middle. I just need it get a better camera. But for now it just me with my phone in my shed/workshop. I really only started trying hard on UA-cam in August
MWBC are difficult in more applications with the dual functions AFCI/GFCI requirements. I’ve had issues with dual function reps tripping on dual function. There’s not a lot of dual function 220 out there for every panel manufacturer. No, handle tired gfci’s won’t work.
Good and educated video my friend, but how mathematically came up with the 180 volts and 60 volts, I know it must be ohms law, can you explain it. Thanks
3:14 so it’s a basic voltage divider? I’ve used those in analog audio circuits for guitar pedals. Hot plates are a good example to use as a demonstration because they’re a resistive load. I’d imagine with more common household appliances you’d have much more wacky behavior.
I really liked your last point: until you develop an intuitive grasp of the way 240v split-phase AC is distributed, you will never truly understand some of the electrical gremlins or dangerous situations you might encounter, whether or not your house has multiwire branch circuits. It's not just houses - I found this problem on a boat once that kept burning up shore power cords...turns out an inadvertently bonded neutral in the electrical panel was causing more than 100% of the rated current to go back over one neutral between the two cords.
so, the code is to use a wire nut because they trust a wire nut to be a more secure connection compared to the screws on the duplex recepticle? Because in either case the neutral could get broken, and I would've thought a screw would be more secure. I've found more loose wire nuts than loose screws.
@@raymenista I think is more about the receptacle might be removed intentionally during repair work vs which connection might fail first but idk for sure
You have good videos. Watching this one I think I will stay away from shared neutrals. Don’t mean to change the subject but does a metal building need to be attached to ground in subpanel?
So there is one thing that I don’t understand. So I understand that the neutral does carry the load due to the fact that it’s alternating both and forth across the coil from leg 1 (or 2) to neutral. I know that a pen tester will not sounds off on a neutral. But it will sound off if you break the neutrals up and you have the primary neutral (still hooked up to device with power on). But as soon as you reconnect the path way the pen tester goes silent on the neutral. Example incase my explanation was horrible. Non and tube style wiring. Single conductor going to light then from light to the switch. (I know this is illegal now, this is only for the explanation) with switch of what would be recognized as the neutral is sounding off. Switch on sound from pen tester goes away. It’s the same with today’s wiring. Power still on disconnect the neutral from its self and pen tester goes off, reconnect pathway and pen tester goes silent. I know pen testers work off compacitence but there is definitely something there, so why doesn’t it see it?
@@creating-infinity so voltage only exists and difference in potential between two points. So you regular meter using two leads usually one to a hot wire and one tona ground reference. The pen tester does indeed have two "leads" the tip is one the tip but it still needs a ground reference, the tip sense the potental of the conductor it's near. Now to get its reference to ground the pen tester using (dash)capacitive coupling and your body to get is ground reference for the earth the neutral is bonded to(dash) the part between the dashes seems like magic but I am quoting guys like electroboom. But when the white wire (on the other side of a load) is connected to the neutral from the feed it now has the same potential as the ground reference so pen doesn't chirp because there is not potential higher than it ground reference. This is why pen tester says to hold them in your hand. Yes they can work when not held in a bare hand but they will work better when held by a person
@@Stevenj120volts that does make sense. So the reason why it beeps on the hot is because, well to state the obvious, it’s not grounded and the voltage and flow is being held back by the resistance of the device but as soon as it passes the device to go back to the transformer it’s potential is the same as 0 meaning no voltage difference, at least not enough to make it beep. I’m hoping I’m saying that correctly.
@ Sorry I mean 14/3 wire. Obviously subpanels and other 240v loads need 3 wire, I shouldve said 3 wire should never be allowed to feed multi circuits for the reasons youve shown. (Im in Canada)
Many commercial buildings even call for shared neutrals as a money saving measure. Then there is the whole part of derating neutrals as well. Excellent explanation!!
I was one of those guys installing all those single and 3 phase 3 and 4 wire networked circuits in Chicagoland for years. The danger was understood by professionals and accepted at the time. This was before homeowners were doing their own wiring repair with little knowledge of these systems. All wiring in our area, residential and commercial, was in metal conduit per local codes, and it was all about saving wire and reducing pipe size. With the introduction of harmonic loads generated by computers, something a normal meter couldn't see, overloaded neutrals bacame prominant and enlarging the neutral became the recommendation. Shortly after, the idea of handle ties came into being to reduce the safety hazard. In the romex world there was a lot less of this issue but it could still be found. You always had to be on guard when troubleshooting these MWBC's live as you could easily fry something on either circuit by simply pulling wires or devices out from a box and inadvertently having a wire come loose. You knew you were trouble when all the lights got exremely bright or you smelled fried electronics! All electricians need to have this knowledge in their arsenal whenever doing any troubleshooting. I'm glad to see you explain this phenomenon so well.
Great comment, thanks for sharing your experience
Been doing electrical for 25 years!!!! Teach this old dog new tricks!!!!!!!
This was super interesting. A few years ago my family's old farmhouse lost the neutral line from the street and we saw all of that wonkiness on different circuits in the house. It took far too long to figure out what had happened since we hadn't "lost" power and no breakers were tripped. While it eventually was diagnosed and repaired, I didn't understand until now why we still had some power, but obviously not as it was supposed to be.
I learned the white-board method in the Navy. Thank you. A lot of ppl need the visual explanation, we keep that in our head instead of a conversation.
Excellent video!
Very well explained and demonstrated
Many commercial buildings even call for shared neutrals as a money saving measure. Then there is the whole part of derating neutrals as well. Excellent explanation!!
Phenomenal explanation! I think you may have a new member soon, keep it up brother
7:34 LOL I was about to Subscribe and realized I am already a Sub. Excellent job man!
About 10years ago I had a bad neutral connection at the service coming into my shop .Like you say a lot of bad stuff happened the red seal electrician from the electric company came out took a look at what was happening in the shop and said its not us its a problem inside your building and left .I work on dc electrics not read seal in AC work ,in 35 min I found it at the pole ,told the electric company they said in order for them to come back out I would have to get a certified electrician to inspect my shop a make an official report to them .screw that I fixed it myself .Side note they added 190$ to my monthly bill for the service call .You either pay or they cut your power .what a world you pay for some one else's incompetence By the way that was a fantastic and informative video. Keep up the good work.
Appreciate the explanation. You’re a fantastic instructor.
I would like to add that at 6:45, the reason the sum of the currents adds up and goes back on the neutral is that the circuit is now wired in parallel, as they are on the same leg of the panel. So basically, steven is illustrating the principles of series vs. Parallel where current adds up but voltage stays the same (when wired in parallel) but in series voltage changes while current is the same. Brilliant explanation by the way,
Master electrician in Boston
Great! You have a different approach in explaining wirings. 👍👍. Keep it that way. More & more will come
Your videos are seriously fantastic for the curious mind. Every time I watch something that you create, I'm left having learned something valuable. Thank you .
Nice demonstration. Thanks for sharing your knowledge.
Freaking love your videos please don’t stop.
@@CcCc-go1eh thanks... The tik Tok ban has got me worried most of my funding comes from what tik Tok pays
Great stuff here Steven! A fellow Mainer sparky here. Well done, Keep it up!
Your videos are goated mann !!
There is an inspection channel (maybe Morgan something?) with several light bulbs on a board and they demonstrate the imbalance that can occur with an open neutral. It's a great demo.
Resistance in a series circuit is additive, current is the same through all resistances, and voltage drops across resistors is the sum of the voltage source.
Ok. I get it now. Thank you for the excellent explanation. I will continue to NOT use multi wire circuits and to rewire those that do find in the wild.
Love the video. I’m learning a lot
GREAT JOB explaining in depth HOW it actually works, Thanks Steven, just one day Im gona be a good electrician like Steven..JUST MAYBE..LOL..U THA MAN 💪
@@chrispate2788 thanks
10 years ago I had to move into a double wide mobile home. I was there for about 8 months. About 7 months in, I came home one day and flipped on the light switch in the kitchen and the bulb went super bright and blew out. The fridge was out, and the microwave would not work. The other half of the mobile home and all the lights worked normal including the tv.
I called out an electrician and he figured it out in about 30 seconds.
The grounding electrode conductor was corroded and the panel had no ground any longer.
Half the trailer was 220 and the other half was still 120 he said because of the way they wired mobile homes back then. It was built in the 1970’s.
He cleaned every conductor end in the entire panel and put it all back together.
I replaced a fuse on the fridge and threw out the microwave.
Great info. Thank you.
Good vid, showing it like it is!
Good job
I used to run multi wire branch circuits about 20
Years ago we ran conduit everywhere so it was easy to do harder to
Do it nowadays with all the code requirements it was called a network circuit
This guys is great!
Why film everything narrow? Turn phone.
@@kcb5336 thanks. The vertical camera is because my primary page is tik Tok and IG 136k followers and 61k followers. Mostly on UA-cam I am just filming shorts or reposting my stuff form other pages. When I try to video horizonal my camera is now on the edge but my eye are still looking into he middle. I just need it get a better camera. But for now it just me with my phone in my shed/workshop. I really only started trying hard on UA-cam in August
MWBC are difficult in more applications with the dual functions AFCI/GFCI requirements.
I’ve had issues with dual function reps tripping on dual function.
There’s not a lot of dual function 220 out there for every panel manufacturer. No, handle tired gfci’s won’t work.
Good and educated video my friend, but how mathematically came up with the 180 volts and 60 volts, I know it must be ohms law, can you explain it. Thanks
If i make up a box that has 208 or 240v potential and its a 120v application, i will pigtail and label or 3m tape 'band' each circuit.
3:14 so it’s a basic voltage divider? I’ve used those in analog audio circuits for guitar pedals. Hot plates are a good example to use as a demonstration because they’re a resistive load. I’d imagine with more common household appliances you’d have much more wacky behavior.
Hi can you make a video on the correct way for 15 amp receptacle/ 20 amp receptacle on a 20 amp circuit ?
Hey I’m a dj and I’m trying to make a 240v extension with 120 receptacles can you please show how to wire it so I can have 120v on each receptacle.
I really liked your last point: until you develop an intuitive grasp of the way 240v split-phase AC is distributed, you will never truly understand some of the electrical gremlins or dangerous situations you might encounter, whether or not your house has multiwire branch circuits. It's not just houses - I found this problem on a boat once that kept burning up shore power cords...turns out an inadvertently bonded neutral in the electrical panel was causing more than 100% of the rated current to go back over one neutral between the two cords.
so, the code is to use a wire nut because they trust a wire nut to be a more secure connection compared to the screws on the duplex recepticle? Because in either case the neutral could get broken, and I would've thought a screw would be more secure. I've found more loose wire nuts than loose screws.
@@raymenista I think is more about the receptacle might be removed intentionally during repair work vs which connection might fail first but idk for sure
You have good videos. Watching this one I think I will stay away from shared neutrals. Don’t mean to change the subject but does a metal building need to be attached to ground in subpanel?
I guess we can call this a series/parallel circuit?
Imagine if you had to pass high school physics before you were allowed to wire anything bigger than an Arduino.
Makes my head hurt
So there is one thing that I don’t understand. So I understand that the neutral does carry the load due to the fact that it’s alternating both and forth across the coil from leg 1 (or 2) to neutral. I know that a pen tester will not sounds off on a neutral. But it will sound off if you break the neutrals up and you have the primary neutral (still hooked up to device with power on). But as soon as you reconnect the path way the pen tester goes silent on the neutral.
Example incase my explanation was horrible.
Non and tube style wiring. Single conductor going to light then from light to the switch. (I know this is illegal now, this is only for the explanation) with switch of what would be recognized as the neutral is sounding off. Switch on sound from pen tester goes away.
It’s the same with today’s wiring. Power still on disconnect the neutral from its self and pen tester goes off, reconnect pathway and pen tester goes silent. I know pen testers work off compacitence but there is definitely something there, so why doesn’t it see it?
I’m hoping Stevenj120volts sees this and responds, but definitely others welcome.
@@creating-infinity so voltage only exists and difference in potential between two points. So you regular meter using two leads usually one to a hot wire and one tona ground reference. The pen tester does indeed have two "leads" the tip is one the tip but it still needs a ground reference, the tip sense the potental of the conductor it's near. Now to get its reference to ground the pen tester using (dash)capacitive coupling and your body to get is ground reference for the earth the neutral is bonded to(dash) the part between the dashes seems like magic but I am quoting guys like electroboom. But when the white wire (on the other side of a load) is connected to the neutral from the feed it now has the same potential as the ground reference so pen doesn't chirp because there is not potential higher than it ground reference.
This is why pen tester says to hold them in your hand. Yes they can work when not held in a bare hand but they will work better when held by a person
@@creating-infinity does that help or was it off topic? And I misunderstood the question
@@creating-infinity I made this video back in February
www.tiktok.com/t/ZP8NyusXD/
@@Stevenj120volts that does make sense. So the reason why it beeps on the hot is because, well to state the obvious, it’s not grounded and the voltage and flow is being held back by the resistance of the device but as soon as it passes the device to go back to the transformer it’s potential is the same as 0 meaning no voltage difference, at least not enough to make it beep. I’m hoping I’m saying that correctly.
3 wire should only be allowed for 3 way switches and smoke alarms
@@mikeymyke how do you plant of feeding subpanels
@ Sorry I mean 14/3 wire. Obviously subpanels and other 240v loads need 3 wire, I shouldve said 3 wire should never be allowed to feed multi circuits for the reasons youve shown. (Im in Canada)
Many commercial buildings even call for shared neutrals as a money saving measure. Then there is the whole part of derating neutrals as well. Excellent explanation!!