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Immerson Wiring

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    #32
    gidxl03
    Registered Users Posts: 16 ✭gidxl03


    After reading this post end-to-end and multi-meter testing of the same switch bought in Woodies, here's my understanding;

    Mains-in Neutral to bottom right Supply-N. Internally connected to N-OUT on top right (impedance 0 Ohms).
    Mains-in Live to bottom middle Supply-L. Internally connected via Single Pole(On/Off) switched to L-OUT on top right.
    L-OUT on top right has to be externally connected via your own jumper cable (2.5mm sq) to 20Amp/250V on bottom left.
    20Amp/250V L-COM on bottom left connected to either Sink-L or Bath-L via Dual Pole switch (Sink or Bath, 3Ohm-closed or 50Ohm-open)
    Sink-L on top left connects to SINK of immersion element
    Bath-L on top left connects to BATH of immersion element
    N-OUT on top right to N of immersion element

    Note:
    L-OUT to N-OUT is 23Ohm (Resistance of the cold neon light)

    Question:
    Why did the manufacturer not internally wire L-OUT to 20/250-L-COM?
    Why is impedance of open switch to sink/bath only 50 Ohm?
    Does anyone have a link to the spec?
    Have tested this wiring and although it is heating the immersion as expected, the neon light does not come on in any switch configuration.


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    #33
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,596 Mod ✭✭✭✭2011


    gidxl03 wrote: »
    After reading this post end-to-end and multi-meter testing of the same switch bought in Woodies, here's my understanding;

    In my opinion this is not a great place to purchase electrical accessories as they tend to be overpriced and often of questionable quality. Having said that I have used them when stuck and was delighted to have to option (as they are open on Sundays). You will have more choice and pay less in a proper electrical wholesaler.
    Mains-in Neutral to bottom right Supply-N. Internally connected to N-OUT on top right (impedance 0 Ohms).

    Where the terminals are placed will depend on the manufacturer.
    The multimeter will measure resistance, not impedance which is fine for a heating element.
    Remember multimeters have an internal battery as such are DC which will only “see” the resistance component of impedance.

    As you say it should be a very low resistance between neutral in and neutral out terminals as they are connected together internally.

    Mains-in Live to bottom middle Supply-L. Internally connected via Single Pole(On/Off) switched to L-OUT on top right.
    L-OUT on top right has to be externally connected via your own jumper cable (2.5mm sq) to 20Amp/250V on bottom left.

    Again the terminal positions / layout and whether there is a jumper cable or not will depend on the manufacturer.
    Note:
    L-OUT to N-OUT is 23Ohm (Resistance of the cold neon light)

    Nope.
    If the neon was 23 Ohms then at 230V according to Ohm's Law it would draw 10 amps and would consume 2.3 kW (as much as some kettles)

    Question:
    Why did the manufacturer not internally wire L-OUT to 20/250-L-COM?

    Sorry I don't really understand the question. However maybe this will answer it for you: Some manufacturer's will do the internal wiring, some won't. Obviously they can save a few bob by getting the end user to do it.

    Why is impedance of open switch to sink/bath only 50 Ohm?

    Its not. The resistance (or impedance) across a properly working switch is far higher than that.
    I assume you are measuring the resistance with the cable or immersion elements connected? To measure the resistance across a switch have everything disconnected otherwise you will be measuring the resistance of whatever is connected.
    Does anyone have a link to the spec?

    The wiring arrangement is generally marked on the back of the switch. This will vary depending on who made it.
    Have tested this wiring and although it is heating the immersion as expected, the neon light does not come on in any switch configuration.

    Either the neon is faulty or it is not connected properly.

    By the way a 3 kW element will have a resistance of around 17.6 Ohms and a 2 W element will have a resistance of around 26.5 Ohms.

    Ensure that all connections are tight!


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    #34
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    The 23 ohms read across L-N (out) is reading one of the elements, and will be approx 17 or 26 ohms for bath/sink respectively. Which one is read depends on the bath/sink switch position.

    An ohms reading sink to bath will give the bath and sink elements in series, so for the above would be 43 ohms.

    Depending on the immersion elements, and how accurate the measuring meter, that is what I would think has been measured to give the results seen.


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    #35
    kramer1
    Closed Accounts Posts: 305 ✭✭kramer1


    Qelres. wrote: »
    Immersion heaters must be the worst electrical appliance ever.

    More problems than you can shake a stick at

    I also don't get the current obsession with smart control of same

    No, they're great. Last for years, easy to change and very little problems with them if installed correctly initially.


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    #36
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,596 Mod ✭✭✭✭2011


    Qelres. wrote: »
    Immersion heaters must be the worst electrical appliance ever.

    They are expensive to use, but as a standalone back up to a boiler they are great.
    More problems than you can shake a stick at

    They are very simple and cheap to fix if there is an issue. I think a new immersion element is around €30. Personally I have found them to be very reliable.
    I also don't get the current obsession with smart control of same

    It is so cheap to install smart control and it can save so much money. A Sonoff TH16 controller is around €15 and it uses a free app. Where could you go wrong?


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    #37
    looksee
    Registered Users Posts: 28,595 ✭✭✭✭looksee


    Qelres. wrote: »
    Immersion heaters must be the worst electrical appliance ever.

    More problems than you can shake a stick at

    I also don't get the current obsession with smart control of same

    I had one fire and one narrowly-avoided fire directly related to immersion heaters, mostly because of the time clocks. I don't have a timer on my current one and only use it in case of absolute necessity.


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    #38
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,596 Mod ✭✭✭✭2011


    looksee wrote: »
    I had one fire and one narrowly-avoided fire directly related to immersion heaters, mostly because of the time clocks. I don't have a timer on my current one and only use it in case of absolute necessity.

    If installed correctly they are very safe.
    Why do you think the timer increased the risk?


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    #39
    kramer1
    Closed Accounts Posts: 305 ✭✭kramer1


    2011 wrote: »
    If installed correctly they are very safe.
    Why do you think the timer increased the risk?

    Probably people using the wrong clocks. The ones that were rated 5/6 amp looked a lot like the 16 amp version s


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    #40
    gidxl03
    Registered Users Posts: 16 ✭gidxl03


    Bruthal wrote: »
    The 23 ohms read across L-N (out) is reading one of the elements, and will be approx 17 or 26 ohms for bath/sink respectively. Which one is read depends on the bath/sink switch position.

    An ohms reading sink to bath will give the bath and sink elements in series, so for the above would be 43 ohms.

    Depending on the immersion elements, and how accurate the measuring meter, that is what I would think has been measured to give the results seen.


    @2011 + Bruthal : Many thanks for the reply.

    Re: Where the terminals are placed will depend on the manufacturer.
    Note that my post was w.r.t. the image that the OP provided (mine looks identical). Also, turns out that my wife did not get it in Woodies.

    Re: The multimeter will measure resistance, not impedance which is fine for a heating element.
    Got it !

    Re If the neon was 23 Ohms then at 230V according to Ohm's Law it would draw 10 amps and would consume 2.3 kW (as much as some kettles)
    I thought that the resistance of the cold neon would be much much less that the resistance a millisec after it has lit up. It has been a very long time since I studied electronics .. but I think it is called 'in-rush' current. Anyhow, interesting but completely academic.

    Re the expected resistance
    Many thanks for the info on resistance of sink and bath, its a good reference.

    Re the neon light not working. Confession: I should have mentioned that on my first attempt to put the switch in series with a timer, I pinched the L wire input to the timer when screwing the timer face back on. So the screw next to the trapped L may have been live - yikes! The screw is not connected to ground (multimeter test) so I don't know how the MCB tripped but thankfully it did. I replaced all the wiring, found that the old timer was broken (power light always on, even when switch was off) so I replaced it (correct rating for immersion) and now all is working except for the neon light on the switch (I've monitored it closely while immersion turns on and off so am confident that it is safe but, as advised by an earlier poster, would have got an electrician if I had to start over). I still don't know how a short in the timer could have broken the neon in the on/off switch since the large current of the short would not have gone through it.


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