BROKEN NEUTRAL - HOW TO FIND IT - HOW TO TEST THE CIRCUIT AND THE VOLTAGE READINGS TO BE EXPECTED

Рет қаралды 50,984

11 ай бұрын

What happens when we have a break in the neutral conductor?
This LearnElectrics video came about because of several posts on social media about testing electrical circuits that have a fault. In this video we will look at a situation that I had, a while back, in a domestic property with a radial socket circuit and how a broken neutral affected the test meter readings.
There are always many questions on broken neutrals, what effect will they have on the circuit, for instance or how can we spot a broken neutral and why are there different voltages around the circuit.
Moving on to a lighting circuit, I once had a message that when the lights are turned on, they don’t come on, but when the customer tried to fix it himself, he got a shock off the neutral - why?
And many more.
We will start off with a standard radial socket circuit with 5 outlets, and we will keep the explanations and reasons very simple, so that everybody understands.
In this video we will show you how the voltage readings can be affected, what makes the voltages change, and what these test voltages are telling us; the clues they are leaving us so that we can find the fault more easily.
And always remember to work safely, especially if carrying out live testing.
This is video number 205 and to view all our videos type in LearnElectrics all one word into the KZfaq search bar.
Visit our KZfaq channel where we have many more videos on a wide range of electrical topics.

Пікірлер: 70

@whitefields5595 5 ай бұрын

This is what KZfaq is for. Short concise explanations with excellent graphics, free at point of use. Thanks for making the effort to publish.

@learnelectrics4402 5 ай бұрын

Glad to help, it makes it all worthwhile. Thank you.

@richardlewis5254 11 ай бұрын

I have tried explaining this to our apprentices and get a confused look back. I will be showing them this from now on, thank you

@learnelectrics4402 11 ай бұрын

Glad it was helpful and please do, you are very welcome. Spread the word, if it helps then that is great. Dave.

@no_short_circuit 11 ай бұрын

Thanks again for taking the time to explain things in ways that I can understand.

@learnelectrics4402 11 ай бұрын

Glad to help and thanks for supporting the channel. Dave.

@brianhewitt8618 11 ай бұрын

Fault finding is always interesting, thanks dave

@learnelectrics4402 11 ай бұрын

Totally agree Brian. It's the chase to find the fault and then when you find it - was that it? thanks for watching, Dave.

@freezefoot 11 ай бұрын

Thank you for this. Much appreciated as always.

@learnelectrics4402 11 ай бұрын

My pleasure, glad it was useful. Dave.

@abdirizakhassan1073 11 ай бұрын

Thanks Dave You are great teacher

@learnelectrics4402 11 ай бұрын

Thank you so much, I appreciate your comments. Dave.

@davidpatterson1574 11 ай бұрын

Thanks Dave-very informative video

@learnelectrics4402 11 ай бұрын

Glad it was helpful David and thanks for watching, appreciated.

@bashiruosman473 10 ай бұрын

Great explanation. Well done ❤.

@learnelectrics4402 10 ай бұрын

Glad it was helpful and thanks for watching.

@Paulrogbucksbeach 11 ай бұрын

Yes it’s an interesting one. I’ve had a poor mains neutral and the lights were still working as the earth ground was the return. Pretty dangerous situation. Sometimes can be hard to spot. Great video very informative

@learnelectrics4402 11 ай бұрын

Thanks for the interesting feedback, appreciated, and thanks for watching. Dave.

@paulellam6926 Ай бұрын

Good stuff as always, helps to understand behavior of the circuits in fault conditions. many thanks!

@learnelectrics4402 Ай бұрын

Happy to help and thanks for watching.

@pauldendleguitar 8 ай бұрын

Another excellent tutorial.

@learnelectrics4402 8 ай бұрын

Thanks again, much appreciated.

@user-qi8tv2sj4m 4 ай бұрын

Very useful. Thanks mate.

@learnelectrics4402 4 ай бұрын

Very welcome, thank you for watching.

@TitchgamerRG 11 ай бұрын

Great video as always Dave. Come across this a few times myself! The last time was on a electric Hob though!

@learnelectrics4402 11 ай бұрын

Thanks Andy. Yep, this can make an appearance anytime, anywhere. Hope you're keeping well. I must get up to the Midlands some time. We used to have some crackin' Christmas parties.

@TitchgamerRG 11 ай бұрын

@@learnelectrics4402 yup I have just finished organising a charity event my next task is to get the gang together for a few bevvies!

@curentarul 11 ай бұрын

Great video! Maybe in the future, you will make a video about the broken neutral in three-phase circuits, where the effects are more serious. Thanks!

@learnelectrics4402 11 ай бұрын

I think I should, someone else also commented about 3 phase problems. It's on the list to be done. Thanks. Dave.

@TheYohtube 11 ай бұрын

And also the use of 3 pole and 4 pole main switches in 3 phase distribution boards.

@nunyabiznes80085 6 ай бұрын

I'm keen on this too. I have a job coming up where i have to find an answer to an issue on some lab equipment, which is a 208v 3 phase circuit. L1: 96V - E L2: 132V - E L3: 115V - E N - E: 20V 208v between phases.

@nuwansampath7348 9 ай бұрын

Thank you.

@learnelectrics4402 9 ай бұрын

You're welcome and thank you for watching.

@30mAkills 11 ай бұрын

Here in 3 phase 4 wire supply (India) this fault is known as floating neutral. In domestic service this is disastrous as the voltage will float anywhere from 0 to 415 between phase and neutral point due to imbalance and spoil the connected appliances.

@learnelectrics4402 11 ай бұрын

Exactly right, with 415 volts on the end of a wire, it can do a lot of damage. I used to work in India so I've seen similar first hand. Take care, thanks for watching, lots more to come. Dave.

@vincenthigginbotham8729 Ай бұрын

Thanks

@learnelectrics4402 Ай бұрын

Very welcome, thanks.

@johnedwards1746 4 ай бұрын

Help question. I plugged a transformer 110v in my plug socket up stairs landing which was attached to a 110v circular saw.. I was just testing the saw and transformer to see if they work properly as I’d lent it to a friend .. the transformer worked and saw started ok. I un plugged them both and packed them away…. Then I plugged the hoover in the same socket it didn’t work?? I tested the socket outlet no 240v. Odd so I unscrewed the front and put one of those 🖊️ pen testers on the live 240v ok. Then the neutral gave me a reading but as I put the tester on the green earth it’s live ?? I no nothing but bits about electrical wiring… so what I did was knocked up a build with two wires on it. I attached one to the live ( rear of socket) and the blue to the neutral bulb 💡 didn’t work?? But shows 240v at the live. Then I put the blue wire onto the green terminal and the bulb lit up ??? Confused 🫤 I tested several other sockets only 1 other doses this which is off set below the upstairs one. Same situation on doing the same tests. Then I did the same test on a good plug socket. Red blue through the front three pin on two pins bulb works. Removed the front did the same on the rear of the socket red and blue ! Bulb doesn’t work????? Tried it red to red and blue to green earth bulb 💡 works. ??? I’m puzzled how it works from the front and not from the back. An why the other two sockets don’t work? I’m thinking perhaps it’s either the socket front/s have blown on both or a wire but how do I know which it is or which wire ?? Any expert advice would help

@learnelectrics4402 4 ай бұрын

Without being on site its difficult to say. Isolate your circuit and carry out the continuity and polarity checks as per Part 6 of the Wiring Regs book. That will hopefully show where the problem is.

@funnyshortsdaily515 23 күн бұрын

I have a hot to ground that has 120v and 17v to neutral. Similar receptacle has the opposite.. is this a neutral open?

@learnelectrics4402 21 күн бұрын

Have a look at this video on neutrals. Dave. kzfaq.info/get/bejne/ndhmjcKTp8_dZZs.html

@ja_adam_ 11 ай бұрын

Basic question for you but I was wondering, am I right in saying that current returns down the neutral not volts. I thought voltage was needed to push current round a circuit so how does it return without this ? Also how can there be current returning if it is been used in the appliance? Also where does this current go? Does it disappear at the transformer, can it not be reused? Please answer thanks for your videos

@learnelectrics4402 11 ай бұрын

Think of a hot water central heating system. The hot water goes to the radiator and gives out its energy as heat into the radiator, the appliance, It then returns as cooler water to the boiler to be reheated and start all the journey again. The electrical flow is just like this. Keep learning, keep watching the videos, it all makes sense eventually, trust me.

@deang5622 11 ай бұрын

Current flows, voltage does not. Voltage is always across two points. It's a potential difference. Which is why when you see people saying they have 240 volts, the question is what two points are you measuring it between?

@deang5622 11 ай бұрын

Sadly the diagram shown at time index 0:48 of the radial circuit showing the voltages is not complete. It's not accurate. It depicts 240 V and 0 volts and it gives the impression there is no voltage on the neutral line, and that is not correct. The voltage is a potential difference between two points. And if you use a multimeter (on an AC voltage range) and measure voltage, putting one probe on to the neutral line, and placing the second probe also on to the neutral then you will get 0V. But if you also placed both probes on to the live line you would also get 0V ! And trust me, you don't want to touch the live line! Now if you place one probe on the live line and the other on the neutral line, the multimeter would show 240V. So the live line is at 240 volts, right? Yes. Ok, now swap the multimeter probes around and you still get 240 volts, showing that there is 240 volts present on the neutral. But the diagram incorrectly shows 0 Volts. The reality is that it is AC and the voltage is swinging up and down on both lines. It is not fixed at 0V. Each is going up to +339 V and down to -339 V. So the diagram shows 0 volts on the neutral line, but that is not the case. There are two things missing from this diagram. Firstly that voltages are typically represented as an arrow between two points on the diagram with the voltage written adjacent to the arrow. This then shows you the potential difference between the two points, which is the correct way to depict voltages. But sadly most electricians do not do this because of the poor quality of their training. The second thing that is missing is the connection from earth to neutral. And this is critical to understanding why if you touch the neutral which has 240 volts on it, as to why you are not electrocuted.

@callen2858 9 ай бұрын

@@deang5622 In a single phase system, the AC voltage is swinging up and down, but ONLY on the live line. If you place one probe on the live line and the other on the earth line, the meter would show 240V, correct? If you swap the probes around you still have 240V, correct? So does that mean you also have 240V on the earth line? This is the same logic you used with the neutral line. And if you connect the earth to neutral it is now safe to touch? You have a misunderstanding of how a multi-meter works. The 'COM' wire does not mean '0 volts'. It is a reference to which the other wire, (V), is compared. You can use an AC voltage as a reference, which is what you are doing when swap the probes. It gives the appearance of a voltage being on the neutral line when in reality it is your reference that is moving positive and negative. You said each line is going up to +339 V and down to -339 V (the peak voltages), but in reference to what point? If you have +339 V on the live line, what is the voltage on the neutral line at that same moment? If it is +339 V, then you have one phase with no potential difference between them. If it is -339 V, then you would have two phases 180 degrees apart with a 678 V potential difference between them. The only way to fit your description is with two phases, 90 degrees apart. All these options will also show as 240 Vrms between neutral and earth lines.

@mundent 3 күн бұрын

Looking at the tables, at no point is there 240 between L&N whether the lamp is in or not. I have a fault on the kitchen sockets where there’s no power to the appliances but there is 240 between L&N. I was getting 240 between N&E then I disconnected the dishwasher and the fault cleared, so I thought. It showed 0v between N&E, 240v between L&N so I plugged in the kettle and nothing. Tester shows L/N reverse but even so, I should still get power but nothing

@abcddef2112 8 ай бұрын

Im confused in my situation, all lights and sockets work. However one of the light (led) flickers when turned off. Checking the switch both neutral and life wire are hot.

@learnelectrics4402 8 ай бұрын

Take a look at this video on lighting circuit faults. Good luck. kzfaq.info/get/bejne/iZeErdVmu76cXYU.html

@synthwave7 11 ай бұрын

I have a similar problem and the electrician could not find the fault. When my light in the lounge is off, the bulb still glows. Measuring the 2 pins in the light socket shows 36 Volts A.C. while the switch is off. Surely this cannot be induced voltage ? So where does 36 V AC come from in a 240 V circuit then ?

@learnelectrics4402 11 ай бұрын

That sounds like another circuit sharing some of your lighting circuits conductors. Take a look at this video on shared neutrals. kzfaq.info/get/bejne/ndhmjcKTp8_dZZs.html

@ja_adam_ 11 ай бұрын

Also in this case of the lamp plugged in to the faulty socket making neutral 230v .. why does this not short circuit?

@learnelectrics4402 11 ай бұрын

Have a look at the video again and look for the part where it shows that the broken neutral conductor is not connected to the rest of the neutral. Thanks for watching. Dave.

@deang5622 11 ай бұрын

Best advice I can give, *always* draw out a circuit diagram. This is the best way of analysing what is going on. If you can't draw out a circuit diagram then, seriously, put as much effort as you possibly can into learning enough about electricity and electrical circuit theory until you can do it. It's a fundamental skill that you need in this business. Get your head around what makes an electrical circuit, Kirchoff's two laws covering voltages and currents.

@ammarbasrah1362 9 ай бұрын

Professor, in short, when examining the buffer, we separate the pregnancy and the swivels off When examining continuity, we also separate the load

@learnelectrics4402 9 ай бұрын

Thank you for watching.

@tissa1979 11 ай бұрын

Dear sir How book 18 edition wiring regulation exam

@learnelectrics4402 11 ай бұрын

You will need to contact a training centre or college near you that does the exam. Use our videos to back up the classroom training that they will give you. Thanks for watching.

@deang5622 11 ай бұрын

Read the entire book and memorise it 😅😂

@matt4436 11 ай бұрын

Usually fault like this you will assume is reversed polarity or dead short. You made this crystal clear in a few minutes video... Best teacher ever!

@learnelectrics4402 11 ай бұрын

Thanks Matt. If it helps, the video has done it's job. Dave.

@OnTheGoKRO 6 ай бұрын

I have a issue… lol. Help YO SUBSCRIBER! Haha. but fr any tips would Be appreciated One day My light randomly stops working… (2 light fixtures to one switch! And other one works fine) …. So I disassemble the bulb fixture that isn’t working and test the wires….WIRES are getting power… but bulb isn’t working…SO…I go ahead and buy a new connection where the bulb screws in…. I Install new bulb connection and install new bulb … STILL NO light on…. So I check the power and IT has power and correct volt…. But the bulb still isn’t coming on?! Lol. ------------- -So the electric to the fixture is good -The bulb connection is hot and good - Electricity in the wires are good - connections are tight…. Idk what to do …. Could it be the switch?! Since two fixtures are tied to 1 switch…. Maybe one of the wires to 1 of the fixtures came lose over time?……. Any help would be appreciated. Trying to help my dad here and I’m stuck haha

@learnelectrics4402 6 ай бұрын

You will need to start your testing with low ohms tests, prove the continuity of all the cables. Take a look at these videos 3 plate kzfaq.info/get/bejne/psWhfdtl0cnUYYk.html 2 plate kzfaq.info/get/bejne/gpeTrNKip7LPlX0.html common lighting problems kzfaq.info/get/bejne/iZeErdVmu76cXYU.html

@markyd2633 11 ай бұрын

Had this fault on a lighting circuit last week..........240v at the neutral in a jb . ......never take for granted that a neutral will be safe to touch.......It hurts

@Poorlybobsdad 11 ай бұрын

That’s because it’s not a neutral in that state, its a blue or black coloured live conductor 😁

@learnelectrics4402 11 ай бұрын

Absolutely Mark. Thanks for the feedback. Dave.

@learnelectrics4402 11 ай бұрын

Exactly right, and as Mark says, it hurts. Thanks for the comment, appreciated. Dave.

@deang5622 11 ай бұрын

This is why I don't approve of the diagram at 0:48 as it gives the impression the neutral is at 0 volts and it is not. It is only at zero volts *with respect to earth* and so long as there is no fault in the circuit. The neutral line is at 240 volts with respect to the live line.