I worked for electric utility company 36 years and learned all about bad neutrals and repaired many neutrals. When I retired they brought me back a trainer and one of the things I taught was open and bad neutrals. What they caused we called a power surge due to the imbalance of in coming service voltage. This is not to be confused with a power surge that occurs during lightening storms in the south. The purpose of the neutral in a 3wire or 4 wire service is to balance the hot legs. That was the only answer accepted on the final exam. Also many believe it is ok to touch a neural with bare hands. As long as everything is connected properly you shouldn't receive a shock. How ever if there is a neutral problem somewhere you will receive a shock just as if you touched the hot wire. It's all fun stuff but always be careful and ware your PPE. Better to be safe than dead.
This happened last night during a wind storm, I was confused as hell, since half the light worked, and the other half were bright as hell. Can't believe we didn't blow any bulbs or anything after 12 hours. Thanks for the explanation!
@@morganinspectionservices3840 Cell phone and laptop chargers connected would like not only survive, but work normally during the overvoltage if they were (as they usually are - but not all are) rated for 100-240V for world use. So they'd run happily on 120, 170, 212 or even 240V or down to 100V. So something surviving and even working doesn't necessarily mean it is getting 120V. So you could plug a laptop charger in and have it work, then plug in a hair dryer and have it explode, and mistakenly not blame the power because ("the computer still worked").
Now can I ask an electrical engineer a question. It has always seemed to me that AC voltages of 120 or even substantially lower are very easy to get shocked from, but DC current don't seem to be this way at these voltages. What I am asking is this, is messing around with batteries that are 90 volts or 130 volts a dangerous shock hazard? Landline telephones operate at 60 volts DC power. Antique 20's era radios had battery banks that operated up to 135 volts. I have been powering old radios like this by putting together 9v batteries in series to about 90 volts but have always been a little leery about the safety of handling such things. I have carefully tested lower DC voltages on the back of one hand and couldn't seemingly feel any current. I have somewhat assumed that 60volt DC may not be quite as dangerous for the simple fact that phone wiring is pretty wide open in the public sphere. Could someone clarify this. I have looked quite a bit online a few times to try and find some discussion of this.
I will start off by saying that both AC and DC voltage can be dangerous and fatal, however, the human body seems to tolerate DC voltage better. One study I read says that the human body can withstand approximately five times the DC voltage than it can AC voltage. If this is correct, then it would take approximately 600 V DC to give the equivalent shock that 120 V AC gives. AC voltage, which is alternating current, seems to affect the body more than direct current does. Alternating current has a greater tendency to cause atrial fibrillation than DC voltage does. The human body seems to have a higher impedance (resistance) to direct current than it does to alternating current. Having said this, every body is different, and low DC voltages can sometimes be fatal to some people.
Not only that. As the neutral is bonded to the ground wire the voltage on the neutral gets to any grounded equipment case. This could in worst case kill. Here the instruction is to get out and call the power company and not to return until it is fixed but we have higher voltage.
I’ve had that happen at my house during a hurricane. A tree fell on the drop to the house separating the neutral. As soon as the lights went bright I knew what happened and ran to secure the breaker. It took out the refrigerator, microwave, oven, dishwasher and clothes dryer. Completely fried three surge protecting power strips and burned out a bunch of light bulbs.
Yes, it can be very destructive to electronic equipment. Good thing you knew enough to recognize what was happening and shut off the power as quickly as possible.
Damaged the dryer? Wow. They use 240V usually, but some use 120 also to run some circuits, if that side goes high it could do damage. If it goes low, not so likely.
@@franklofarojr.2969 It fried the circuit board. I replaced it with an old 1980s dryer that has been refurbished. No electronics works better than any new dryer I have had.
Call the power company as the problem is their neutral. If you call a electrician you will be stuck for service call $ , and they don't work on power company lines.. This could be over $100 for a minimum call The power company will service and fix the neutral connection.no charge. These electrical neutral problem s are dangerous and eerie. Our aluminum framed screen porch was measuring 40 to 70 volts. My dog yipped as she went outside because the aluminum frame and door was electrified. I put my fluke black lead into the nearby ground (soil) and the red lead on some aluminum - ac voltages were all over the place. I think the electricity found a ground but also found a ground that energized the aluminum frame which was also grounded. 😮😮
I think that problem only happens in countries using 120 volts because they have three cables going to their house from the transformer (+120v, 0v, -120v). In countries using 240 volts that's not a problem because they only have two cables going to their house from the transformer. If they lose one of the cables the light won't turn on.
Yes, you are correct. It only happens in countries where the voltage is split at the transformer, so countries that only use 220 or 240 V do not encounter this same problem.
A few years back went on a service call where the homeowner had smoked up a flat-screen, DVR, and stereo system after a 1500 watt electric fireplace had been running for about an hour. It was a lost neutral on a MWBC feeding the master bed & living room with backstab connected receptacles. A backstab connection upstream burned out on the neutral. Home was built sometime in the 1970s if memory serves me right. This expensive ordeal would have been avoided had the receptacles been installed in accordance with 300.13 (B) which states the neutral of a MWBC cannot be interrupted by removing a wiring device.
I had a shared neutral on 6 plugs in my garage. A wire nut failed and I had a lost neutral in my house but just on 4 plugs. It destroyed a charger before I noticed the problem.
If a neutral becomes disconnected inside the home, then that’s actually a different situation than what this “lost neutral“ video discusses. We typically call your situation an open or disconnected neutral. I have a separate video on that. Sounds like you were already able to solve the problem. However, if you need it, here is a link. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-BVcNnBKfC8Q.htmlsi=7Gb7tGew_n87GCKy Temperature
@morganinspectionservices3840 That video did a good job describing a lost neural on a 120v circuit. I’m referring to a shared neural. Which acts more like this video. So imagine this. You install a 240v circuit breaker. Then you take a 14-3 from the circuit breaker box to an electrical box with 2 receptacles in it. So going into that box you have red, leg1; black, leg2; white, which is a neutral shared between the black and red; then green, your ground. Red goes to a 120v plug on the right. Black goes to 120v plug on the left. Both plugs have a pigtail going to the single shared white wire. Now disconnect that white wire inside the electrical panel. Plug a lightbulb into both 120v sockets. The energy follows this path. Black wire Light bulb White pig tail Second white pigtail going to the other plug Second lightbulb Red wire So you have 240v going through 2 120v lightbulbs. Being protected by a single 240v breaker. Now you have your demonstration but inside a house. Fun fun watching things smoke. 😁
Just had another issue with the neutral line going to the transformer on the pole. I had some strange power fluctuations again but not as drastic. So I put my clamp meter on one leg going into my panel. Then I turned every other breaker off putting a larger load on one leg. It showed a voltage delta of about 15 volts. I called FPL and they sent a service truck out. He pulled the meter and put a device on it to check and it showed it was just over the allowed difference. After inspecting the ground cable he saw where my neighbors tree was chafing the wire. It was warn down to a single strand. They replaced the neutral drop and it is now fixed.
Thank you so much for posting this video! We had a big wind storm roll through yesterday and knocked out the neutral wire to our home. I wasn't sure why our lights were acting strange; but now I know. Thank you!
Worst case scenario from a floating neutral at the service drop could be electrocution from energized water pipes and metal case appliances with 3 prong plugs, because until I believe the 1978 NEC, a cold water pipe could serve as the sole grounding electrode if at least 10 feet was in contact with the earth, and the connection to the grounding electrode conductor is made within 5 feet where it enters the building, and plastic pipe could have been used to replace a section of corroded metal pipe. Because the neutral and ground are bonded at the main service panel, a double loss of ground and neutral could have lethal consequences. To combat this, a water pipe used as a grounding electrode must be supplemented by grounding electrodes in contact with 8 feet of earth with a resistance not to exceed 25 ohms.
I keep losing neutral on power company side but the lineman wont come out until ive paid an electrician to check its not on my side!! Its always on the utility pole and its costing me a fortune!
That is crazy that you’re having to pay a service call each time. It’s also crazy that it “keeps” happening. It does not make sense that it would happen multiple times.
@@morganinspectionservices3840 They came out to me last week because their equipment made my earth rod live and everything in my house including water pipes! The box on the pole was replaced and the cable down the pole to my boundary. The supervisors came next day only to tell me the lineman had left me with a live neutral! I am quite literally waiting to be electrocuted! They said the neutral is also reading too high.
This happened years ago at my brother in laws house. I was open at the lift pole before the service drop ever reached his house. It smoked his television but the utility company never claimed the fault even after they corrected it. The story is longer but I'll leave it at that.
Even worse in my opinion is when this fault occurs and the return current finds its way back through the equipment bonding conductor tied to utilities, e.g. catv. Imagine the grounded shield on catv carrying back dozens or more amps. Whole home bonding junctions are a good thing but this is what can happen more easily now.
The current flow at 3:45 is backward for a balanced load with no neutral current. The diagram shows the neutral current as additive when it should be subtractive.
I had to go back and watch the video. I’m not following you because I am showing balanced loads on the two legs and then no current flowing on the neutral so I am showing it as subtractive. Please explain a little more and we can discuss this.
I don’t think the two are actually related unless I’m not understanding you. Since lost neutrals typically occur at the transformer or weatherhead or somewhere before the panel, and shared neutrals are part of the branch circuit wiring, they don’t seem related. I do agree that when you share neutrals and one of those neutrals becomes disconnected that you do have a similar situation with the loads and voltages.
When devices do get overvoltaged, what have people seem happen? I have heard of everything from explode, to still work fine (global/universal devices rated 100-240 for example). I had a friend who had some lights go real bright and a frig smoke with a terrible smell as parts burned (not a full fire thankfully)
I just helped a friend diagnose that he had a lost neutral at his home. He was measuring voltages upwards of 200 V. He that somethings stopped working completely while his home had the lost neutral, but once the lost neutral was corrected, everything worked perfectly. I cannot say that that will be the case every time, but at least in his situation it was.
Are there any simple uncomplicated tests that I can do in my house to determine whether I have a lost neutral or not? How do I determine if it's on my end or the power companies end? All the receptacles I've tested so far are reading around 120 (120 in and out) but my refrigerator won't run. I've plugged the refrigerator into different outlets and it's the same. Tried plugging my Skillet into different outlets around the house and it won't work. Thank you!
This is a test that I would do in my house, but I will caution you that you must be very careful. I don’t want anyone getting electrocuted. If it were my house, I would remove the cover from the electric panel and measure the voltages at each main lug. Test between one lug and the neutral, and between the other lug and the neutral. See if you have 120 V on both legs of your electrical system. And make sure you have 240 V between the two lugs. If those tests are good, but you do not have 120 V at the outlets in your house, then I would say the problem is inside your house. If you do not have 120 V when measured as described above, then the problem is likely with the power company.
It is a SureTest circuit analyzer. It’s made to plug into a receptacle and measure voltage, voltage drop, and to tell if the circuit is wired properly.
The three (3) bulbs on either leg are wired in parallel. (Although the two (2) legs are now in series to each other with the lost neutral.) When one bulb is turned off, the Resistance goes up and the Current goes down (in that leg) because they are in parallel. Naturally the leg with the highest resistance (series circuit) has the highest voltage drop.
"When one bulb is turned off, the Resistance goes up and the Current goes down (in that leg) " - i understand that resistance goes up if we swich off 1 light in the circuit because its parallel so it is as if we closed 1 of the 3 roads for the current - so more resistance. More resistance means less current in that leg but both legs are in series so the current is the same. So if the same current is flowing while the voltage is much higher means that a lot more energy is on the side when 1 light is off. Does it make sense the way i rephrased it?
No. When your service loses a neutral, nothing done at the panel that I can think of will change the fact that you will have the two legs in series on a 240-volt service.
@@morganinspectionservices3840 Having a true single-phase system significantly simplifies electrical installations, reduces the amount of copper needed and therefore overall costs because for a given energy consumption in Watts is only half the amperage at 220/240V and therefore half the amount of copper is needed to meet the requirements. Split-phase is a needless complication that offers no real advantages. Here in Europe, for example, I have no split-phase to consider. Everything is 230VAC and uses the same plug and receptacle whether it's a small table lamp or a dryer. No special outlets are used or required so anything can be plugged into any outlet and can draw up to 3KW. In my country the power plugs and receptacles are designed for safety with the plugs have replaceable fuses built-in to protect the wiring and appliance so it's an incredibly safe and flexible system. If the US went 240V then it would also gain the commercial advantage of being able to export electrical to 220/240V countries. The difference of AC frequency is becoming less of an issue, particularly with modern switching power supplies. PC Gamers in the US would also gain the advantage of using more efficient 240V power supplies, and also more powerful ones if needed, which would save energy and reduce running costs.
Thank you for this great tutorial bc I used experienced what turned out to be an broken Neutral wire from the Power pole it wasn't discover completely till my cable guy came & got lit up off the cables ground & came in & cked power outlets & smelt smoke but the outlets all had 199 volts so i quickly killed my main breaker & called the power co & did loose an brand new Window unit but hopefully thaT WAS all Lost
@@morganinspectionservices3840 yes Thanks absolutely but sine I wrote this i discovered the window unit still works but the smell I experienced came from The ac circuit breaker so that wire was replaced & now all seems to be OK ..I hope
I have a pole behind my house with a breaker box and a meter box above it. Two wires run from the pole behind my house out to the main pole on road with the transformer. Am I responsible for everything on the pole behind my house? Thank you!
Typically, the homeowner is responsible for everything after where the wires connect to the weather head just before the electric meter. The electric company is responsible for everything just before the connection at or near your electric meter.
Great video, I have been having problems, I had the electric company come out they said on their side it good, so I bought a multimeter and sure everything is good until I turn on the microwave on certain days some days the microwave doesn't change anything and other days it makes the fan speed up so I go to the meter pole and leg L-1 is 132 and L-2 is 117 so is the problem on me or electric company and could the bad neutral come from half a mile away i don't share a transformer i live way out in the mountains.
You definitely have a lost neutral. However, the symptoms are the same whether it’s on your side or the power company side, so it is impossible to say where the problem is originating. It’s just going to take some investigation. I will tell you this that you would not be the first person I have heard of the power company saying that it’s not their problem and then later discovers that it is. And the reason that you have the problem on some days and not on other days, depends on the load distribution of what is currently running in your home. If you have a heavy load running such as air conditioning,clothes dryer, or things like that, then turning on the microwave will have a much smaller effect on the voltage than it will when very few things are running. I wish I could help you more, but long distance troubleshooting is very difficult. If you can give me any more information, I will help you as much as possible. I would definitely be interested in hearing what you find.
@@morganinspectionservices3840 Thank You so much, and I will give the update of the cure if I ever find it, today I turned everything I could find to bring one leg down, but it would only drop 2 points, the kitchen is on leg 2 so I had hot plates refrigerated, space heater , L 1 at the meter pole showed 120 L-2 showed 124 nothing was running on L-1 but in a few days seems it is usually a hot day it will actually up again. I can measure the house or at the meter pole it's always the same, I was told if the legs are unbalanced at the pole it would be the electric company problem.
I kept having a imbalance on the two legs about once a week so I disconnected L 1 and that seems to fix it but now one side of my house has no lights or outlets, and L 2 pulls down to about 115 volts when using the microwave. So will that hurt anything?
Did you ever think that using green on your schematic to represent the neutral line wasn't a good idea? Green is standard wiring code for non-current-carrying ground, not neutral!
And white is normally the neutral, but white would not have shown up, so I chose green. Yes, I understand that green wire is the non-current carrying ground. How often have you seen blue current flowing through a wire? It’s just an animation, and I hope it serves its purpose.
tho it's still the same concept, the direction of the current is inaccurate before the loss of neutral. However, after the loss of neutral, the animation is accurate. But here is where you're wrong. Current don't reverse direction because of the loss of neutral. so it's more like this (--> -->, ,
I totally agree with you. I was not necessarily trying to show the actual direction of current flow with these animations. I was more trying to show that current flows from the transformer, through the loads, and back to the transformer via the neutral. You are 100% correct that the direction of the electricity does not change when the neutral is lost, but for illustration/animation/explanation purposes, that was the easiest way to animate and explain it. I certainly appreciate you watching and appreciate the feedback.
interesting video! does it mean that UK system is intrinsically safer than US? loosing neutral does not cause this sort of issues - please help me to understand
In the UK, they use 230 volt, single-phase electricity in residential wiring. In this case a lost neutral results in an open circuit where no electricity can flow, so in that sense, you could say that UK wiring is safer than US wiring. However, in another sense US wiring is safer because in the US most circuits are only 120-volt circuits, while all circuits in a home in the UK are 230 volts. 120 volts (which can certainly electrocute someone) should be only about half as likely as 230 volts is to cause an electrocution. This is because current (amps) is what causes the electrocution, and current flow is proportional to the voltage. Current = Voltage/Resistance. This equation shows that for a given resistance of a human body, you will have about twice the current flow with 230 volts as you will with 120 volts.
@@morganinspectionservices3840 can i say that uk system if it fails it fails safely why us lost of neutral does not fail safely because instead of 120 v suddently 240 appears which could burn or damage something?
I can inform you that a loss of the neutral conductor on the 3 phase distribution system in the uk or anywhere else will result in overvoltage on any single phase distribution circuits . It is more common in the US with overhead lines and corroded aluminium conductors.
@@morganinspectionservices3840 I have a main panel, and then a double pole breaker as the "main" for a subpanel, and a duplicate subpanel is in another location (in the barn/shop) and I have a 20 amp 120v single pole breaker outlet there and have backfed power from generator from that outlet after disconnecting the true MAIN breaker and on outlets and lights on one side of the main panel in the home I only get ~90 volt, while the other side is a full 120 volt. It is odd to me, the more I think about it I don't think it is from a lost neutral now as it should change/have same affect on both sides of panel. You got any ideas on it? I know its despised and most of the time illegal, but it just makes me wonder the cause. I no longer use it that way anyhow as I am in process of making a legit transfer circuit.
This demonstration shows exactly how it works on a 120 V residential. Essentially all residentials have two phases of 120V, so what you see in the video is how it works on a typical residential electrical system.
??? What is a lost neutral??? If a person has to ask, call an electrician. The person is definitely not qualified to do wiring. Lights flicker? Lost neutral! Or someone with an arc welder in the neighborhood.
Agreed. Repairing a lost neutral is a job for a professional. It is not a DIY project. However, hopefully this video will help a homeowner to recognize when they may have a lost neutral.
An open or high resistance neutral conn in the panel or meter can will also cause this. Not always upstream. I've been on many trouble calls where the nipple between the two was glowing because of a loose neutral in the panel. Some were never actually tightened by the original installing electrician.
Great info. I guess when I said upstream of the panel, I actually intended prior to any of the branch circuits, so yes the neutral lug on the panel would certainly qualify. Thanks for the clarification.
@@morganinspectionservices3840 You are correct though. Probably 90 percent of my trouble calls were due to homeowners allowing trees to grow up into the service wire and either breaking the neutral, or rubbing it in two midspan on the drop. People don't understand that the power company isn't responsible for their negligence.
