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DIN Rail Terminal Blocks: L/L, L/N, N/L and N/N?

  1. Feb 22, 2017 #1
    Hello,

    I've recently had a slight trajectory change in my career and I'm learning the ropes in electrical panel building.
    I have to order a load of DIN rail terminal blocks and I've come across a few variants and I don't know which one is the correct one for my application, or if it even matters.

    I understand that the L and N stand for live and neutral, I'm not a complete rookie, but in terms of double deck DIN rail terminal blocks, what's the difference between L/L, L/N, N/L and N/N?

    Any help is greatly appreciated, and sorry if a similar question has been posted before, I couldn't find any information about this anywhere!

    Thanks,
    Dan
     
  2. jcsd
  3. Feb 22, 2017 #2

    berkeman

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    Staff: Mentor

    Are you an apprentice to an electrician now? What sources of information are you using to learn this trade? Are you in the US, and if so, do you know what the NEC is?

    Also, can you provide some links to the DIN Rail modules you are asking about?
     
  4. Feb 24, 2017 #3
    Hello, I'm not an apprentice, I'm a qualified controls engineer and have been working with mainly software for 2 years now.
    I'm familiar with the principals of electricity, but not all the tools that are used in the industry.
    This is my first experience with panel building, but I've worked with electrical panels before, just checking I/O to the PLC usually though.
    I'm using a mix of Google and professional advice from colleagues. However, the other 2 electrical guys that work here are usually on site somewhere, so I have limited access to their expertise.
    I'm situated in the UK, our NEC is in Birmingham, I think Crufts is there soon. I expect that's not what you meant.

    I was looking at the following catalogue: http://www.wago.us/media/us/collection/brochures/topjobs.pdf
    If you look at any of the double/triple deck terminals (Page 37, for example), then you'll see that you can specify L/N, N/L, etc.
    Just wasn't sure what that meant exactly. I would've thought that whether it was L/L, L/N or N/L would depend entirely on what's connected to it!

    Thanks for your input!
     
  5. Feb 24, 2017 #4

    berkeman

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    Staff: Mentor

  6. Feb 24, 2017 #5

    anorlunda

    Staff: Mentor

    Sorry, not my field of expertise either.
     
    Last edited by a moderator: Feb 24, 2017
  7. Feb 25, 2017 #6
    > do you know what the NEC is?

    In this context the NEC is the US National Electrical Code:
    https://en.wikipedia.org/wiki/National_Electrical_Code

    It's the US equivalent to the UK's IET Wiring Regulations or, more formally,
    BS 7671:2008+A3:2015 (17th edition with Amendment 3:2015)
    https://en.wikipedia.org/wiki/BS_7671

    You (or at least one of your 2 electrical colleagues) should be familiar with
    the 17th ed. The IET has a list of recognised training providers at:
    http://electrical.theiet.org/training/index.cfm

    I attended a 3 day wiring regs course some time ago. It was rather a whirlwind
    tour but it did provide a useful introduction to a large and complex standard.

    > If you look at any of the double/triple deck terminals (Page 37, for example), then you'll see that you can specify L/N, N/L, etc. Just wasn't sure what that meant exactly. I would've thought that whether it was L/L, L/N or N/L would depend entirely on what's connected to it!

    L=Live, N=Neutral, PE=Protective Earth, of course.

    The terminals in the catalogue are colour-coded: L=grey, N=blue, PE=green/yellow.

    The idea is that you, as the designer, choose the colour of terminal to suit the
    use of the conductors running through the terminal. This lets installation and
    maintenance staff know what type of conductors they are dealing with and makes it
    easier to find their way round a huge number of terminals side by side.

    I expect the N/L and L/N terminals have the upper contacts in one colour and the
    lower contacts in the other colour. I can't see from the catalogue which is which
    but as a customer you could ring the helpline and ask. You ought to choose one or
    the other of N/L or L/N and use that option for all your panels to avoid confusing
    installation and maintenance staff. (If your company already has a standard choice
    obviously you should stick with it.)

    Although this again is not my field, good practice suggests that you should use the
    double terminals for the two sides of a single (1 phase) circuit, i.e. use one
    double terminal to carry the L & N for a single load circuit; don't mix and match
    random L and N wires from different circuits on the same double terminal.

    I found an introductory video at:


    (For US readers, in the UK 'NEC' refers to our National Exhibition Centre, a large
    exhibition and conference venue in Birmingham: http://www.thenec.co.uk/ )
     
  8. Feb 27, 2017 #7

    rbelli1

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    Gold Member

    Yes. I had found a picture that shows this and thought I posted it but it seems to be gone. One or more of the wire openings have a painted color around them. You can just barely see this in the catalog.

    BoB
     
  9. Mar 10, 2017 #8
    Cool, thanks guys.
    Sorry for the late reply, I've been quite busy on other projects.
    But good eye, didn't spot that!
     
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