29 Comments

  1. Peter Clarke
    October 6, 2019 @ 1:31 am

    What would cause a 50% voltage drop on lighting circuit?

    Reply

  2. Northern Giant
    October 6, 2019 @ 1:31 am

    Great explanation. I’m still trying to wrap my head around the idea of shared neutrals with timed loads. Not even sure what to call this to learn more, but basically an appliance which turns itself on and off periodically would make the other line with the shared neutral unpredictably hot and cold.

    Someone suggested shared neutral with a furnace might cause this?

    Reply

  3. Philip Goh
    October 6, 2019 @ 1:31 am

    Thank you for the best explanation on the Neutral Wire. Still confusing….Can you explain why the neutral wire which carries the return current when circuit is "on" does not cause a shock if it is toughed. what happens to that return current?

    Reply

  4. Matthew Suffidy
    October 6, 2019 @ 1:31 am

    I have no formal electronics training, but I understood the idea is the electrical load is supposed to take most of the potential out of the return to neutral. However, in some cases this is not ideal and a non zero potential can be recycled to the power station. For this reason it was my understanding that the grounding lines terminate in an Earth rod, and do not connect to neutral. I think you have to be part of a circuit to get shocked though, even in the case of hot wires…

    Reply

  5. Michael Clark
    October 6, 2019 @ 1:31 am

    People don't understand that neutrals can be overloaded.
    If you have too much load on the neutral conductor it will overheat just like a power conductor and if connected to circuits on different supply phases and you get a loose or floating neutral it can feed 240 volts through 120 volt circuits.
    Been an electrician for over 40 years and unless I'm hooking up a circuit that requires 240 volts I always make sure circuits in a 10/3, 12/3, 14/3 w/gnd that are carrying 2 circuits with a shared neutral, are only connected to circuit breakers on the same phase.

    Reply

  6. esuohdica
    October 6, 2019 @ 1:31 am

    Hi John, at 10:20 you say you don't use this configuration for split load? What is your preferred way then? Cheers

    Reply

  7. DeaDpool
    October 6, 2019 @ 1:31 am

    How can there be voltage between neutral and ground

    Reply

  8. Rob Pettit
    October 6, 2019 @ 1:31 am

    It's a mistake to connect lighting circutzs (which are basically single phase) to a three phase MCB (which is designed for 3 phase equipment, such as a 3ph motor). Lighting can be spread across three phases in order to either balance the load or, in industrial applications, to avoid any stroboscopic effect that may make rotating machinery appear stationary. In both cases, single pole mcbs should be used with each circuit having its own neutral. The other issue with using a 3ph MCB is regarding isolation, as all lighting would need to be off when, for instance, changing a single fitting on one of the phases. Otherwise good vid 😉

    Reply

  9. zjzozn
    October 6, 2019 @ 1:31 am

    👍🇬🇧

    Reply

  10. ck LIM
    October 6, 2019 @ 1:31 am

    Very informative

    Reply

  11. Electroman Hbt
    October 6, 2019 @ 1:31 am

    I like this video

    Reply

  12. Ass ho
    October 6, 2019 @ 1:31 am

    jessus,. we need to get to the point of your title .. SHARED NEWTRALS, !!!!

    Reply

  13. Kim O'Brien
    October 6, 2019 @ 1:31 am

    Interesting but in the US most of these type of problems ended with knob and tube wiring. Also hallways and stairways by code require switches that can turn the hall or stairway light on or off at either or any entry point. We call them three and four way switches. Residential wiring requires at a minimum romex ( a cable with a plastic sheth and a minimum number of three wires black, white (Neutral) and ground (green or bare)). Commercial and industrial wiring can use single wires but the must be pulled into pipe . I've never seen anyone use separate pipes for individual conductors. I have seen a twin pipe three phase four wires each service entrance. Using a single neutral on multiple lighting circuits with a three pole breaker? Nope. To easy for the next electrician to move wire one to a different phase and then exceed the neutrals current carrying capacity. Three pole and two pole breakers are limited to equipment or panels requiring 240 volts or three phase power.

    Reply

  14. Michael Tobin
    October 6, 2019 @ 1:31 am

    In some respects you are correct but very wrong, death thru electrocution are most attributed to neutral failure- a neutral ( neutral are energized} to ground will kill you slowly because you cannot release. This is why all power tools have plastic dielectric bodies to many people were killed with this condition.

    Reply

  15. FishSauce
    October 6, 2019 @ 1:31 am

    hi, if they took a feed off from the downstairs lighting circuit assuming they used twin and earth why not just carry the neutral as well?

    Reply

  16. samdee pride
    October 6, 2019 @ 1:31 am

    I was wondering what the big difference between the neutral and the live were? Since the current is alternating , are they not the same. I realise that the live is often protected by a fuse but does the neutral not effectively become live once every 50th of a second?

    Reply

  17. ROY GOLDING
    October 6, 2019 @ 1:31 am

    What happens if the neutral breaks on the 3 phase system

    Reply

  18. apbosh1
    October 6, 2019 @ 1:31 am

    does current come back out of the ground on the reverse cycle of single phase mains power? Maybe a dumb question but with 50hz ac , surely the neutral is 'live' 50 times a second? help me out please

    Reply

  19. glenn schemitsch
    October 6, 2019 @ 1:31 am

    I have also been shocked by a shared neutral, fortunately only 110 volts across fingers of one hand. it's very common to share neutrals in America, I guess it saves on pulling extra wires. I do believe that it should NOT be called neutral, but name of ' common ' wire also does not suggest that it CAN be HOT. A new name should be used, even the' return' wire designation might be preferred in conversation. When dealing with 230 volt, I am VERY careful not to assume that there is no shared return.

    Reply

  20. phil955i
    October 6, 2019 @ 1:31 am

    Occasionally I work on equipment that has switched neutrals -that can be a bit of a pain to fault find on lol.

    Reply

  21. DON COOK
    October 6, 2019 @ 1:31 am

    Just happened by this excellent video. Very clear concise and easy to follow. Best ever and finally connected the dots for me about neutral vs ground. Thanks

    Reply

  22. John Bainbridge
    October 6, 2019 @ 1:31 am

    Great video, thanks. You say that safe installations require NOT borrowing a neutral from a different circuit. I want to install a series of 3 lights in my attic on the upstairs lighting circuit. I can identify the live upstairs lighting block in the attic junction box using the circuit breakers downstairs. But how do I identify the neutral wire I need to connect to my attic light switch?

    Reply

  23. Chong Yu
    October 6, 2019 @ 1:31 am

    up till 0:55 i thought my monitor broken…

    Reply

  24. Joe West
    October 6, 2019 @ 1:31 am

    If electricity flows fron neg to pos, then why wouldnt the potential voltage be waiting in the neg wire to flow through the resistance and return via pos making the neg side higher in potential voltage?

    Reply

  25. Mike Martinez
    October 6, 2019 @ 1:31 am

    Dude just switch and feed it .a basic 3 way system is hot on one and switch led on a over but if u s/f it u take all the guessing out of .what u are talking about how does that

    Reply

  26. Trolling 4 Dollars
    October 6, 2019 @ 1:31 am

    In the USA, all commons must be tied together in the main panel, and that buss bar has to be connected to earth/ ground. Also, a physical green wire must be run in every conduit, and every junction box must be grounded, as well as each fixture's chassis.

    Reply

  27. therealnightwriter
    October 6, 2019 @ 1:31 am

    Wow, what a crap way to do wiring, I never would have thought of that, much less done that. Glad to learn about it.

    Reply

  28. NickleJ
    October 6, 2019 @ 1:31 am

    If we didn't use earth grounds at all, would a person touching the ground still complete the circuit?

    Reply

  29. george rocks
    October 6, 2019 @ 1:31 am

    I am confused. If this is an AC circuit, in the first half of the cycle current flows from the source to the load through the "hot" or "line" wire and returns to the source through the "neutral" wire. In the second half of the cycle, the current reverses direction and flows through the "neutral" wire to the load and returns to the source through the "hot" or "line" wire. Does ground/earth now provide the return current?

    Reply

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