Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Power/Electrical Plug

  1. Dec 6, 2014 #1
    I'm a student from Newcastle University from Singapore Institute of Technology (A new launched University in Singapore) and am majoring in Electrical Power Engineering. My current final year project requires me to research on BS1363 and try to reduce the amount of copper usage as we know that the copper consumption in the world is getting larger and that copper is a natural resource hence it could be said that it has a finite quantity.

    I am trying to find out the contact resistance = Constriction Resistanc + Filmic Resistance. I do have the formulae available but I do not know what is the radius of the metal to metal contact part.

    I do not quite know where can I head to towards designing of a new plug to alleviate the copper usage.

    Many would say that it's redundant to work on this project but it seems that I do not have a choice but to only work on it. I'm not trying to do something illegally if that's what you're thinking.

    If anyone could help, please. I've been working on this for the past 8 weeks with no results.

    Any papers/forums/journals/articles/teaching are deeply appreciated.

    Thanks in advance!
  2. jcsd
  3. Dec 6, 2014 #2


    User Avatar

    Staff: Mentor

    Welcome to the PF.

    Can you tell us a bit about what BS1363 is? I'm not familiar with it. And to be more clear, you are wanting to look at designing a better wall plug for use with AC Mains power in homes and industry?
  4. Dec 6, 2014 #3
    OK - I used my good friend Google and the BS1363 is a wall plug. This question therefore does seem off base because there are many factors that go into a plug design - but reducing the use of copper because it is a finite resource is not one of them. My point being that the amount of copper used in the plugs is minuscule (tiny) compared to many other uses ( like wire strung for thousands of miles / KM everyday).
    Is your project to make a better plug - one that uses less copper? ( because copper is expensive?) The resistance issue causes heat but this is not really a copper issue - it is for a given contact area (plug to receptacle) how much heat is generated - this plug looks pretty stout for only a 13A rating. So - the question does not add up - and then the whole "I'm not trying to do something illegally if that's what you're thinking" - perhaps try to describe your project a different way?
  5. Dec 6, 2014 #4


    User Avatar
    Science Advisor

    I'd assume the cost of copper in a plug represents one of, if not the largest material cost in the plug so it definitely should be a consideration during plug design. An expensive plug design pushes up the cost of every single portable appliance that uses it.
    The plugs in my own country (NZ) have probably half the prong material that the BS1363 has and is also easier to make, apparently a driving factor in their selection:


    Some BS1363 prongs only have conductive material on half the prong, presumably to save material costs:

    http://mrmobileuk.com/images/product//igo-usb-wall-charger-miniusb-micro-usb-1.jpg [Broken]
    (Phone chargers are also a good example of an appliance where the prong material represents a significant cost to the overall unit)

    I would start by looking at the various plugs in use :
    Then look at how prong material can be reduced while still meeting required standards.
    If you are only interested in reducing Cu use then looking at alternative alloys may yield results - That wouldn't require a plug redesign.
    Maybe a new plug design for lower powered appliances - Where i live a 10A plug can fit in a 15A socket - A new 5A plug that can fit in a 10A socket may save copper for the myriad of many lower powered appliances like phone chargers.
    Last edited by a moderator: May 7, 2017
  6. Dec 6, 2014 #5
    Dear all,

    Thanks for your replies!

    I am required to follow the Singapore's standards which I believe it's almost a duplicate of BS1363.

    My project was recommended by my professor was because he's comparing an UK plug with an Australian plug which both actually works on a 13A rating. So he was saying that why not do a plug that significantly reduces the copper usage yet able to work on a 13A rating like how Australian plugs are as of now.

    Similarly, I understand that the copper usage is definitely much lesser than those which uses huge amount of copper like example the transmission line cable. However, my prof. was telling me that maybe I could start from small as he really find it ridiculous to have such amount of copper where it can be greatly reduced.

    Anyway, I could say that this is an innovative project. He wants us to come out with different designs and do a comparison - in especially with the contact surface area. I'm still researching on this and I did managed to find an article regarding the design on power plugs.

    Attached Files:

  7. Dec 6, 2014 #6
    Yes. It is to design a better wall plug for use with AC Mains Power in homes. I'm supposed to target at both areas - homes and industries. However, it seems that I could start from a normal wall plug before proceeding for usage in the industries.
  8. Dec 6, 2014 #7
    Hi Billy.

    I have tried asking my prof. about changing the type of materials since copper demand gets higher and could be more expensive. However, I was advised that to only reduce the copper usage as I only have 7 months to work on this.

    Each design that I am coming up will definitely cost higher than the current UK plug since it's only a one solid piece of copper instead of reducing the copper in that area - which I intended to do so.
    Last edited by a moderator: May 7, 2017
  9. Dec 6, 2014 #8

    Yes, my project is to make a better plug which uses less copper. I understand that the amount of heat generated in a BS1363 plug will be alright due to the stoutness of the plug. What I was thinking where can I have a headstart to work on having a reduction of copper yet the heat (in case of high surge of current) will not result in a poor contact surface area?
  10. Dec 7, 2014 #9


    User Avatar

    Staff: Mentor

    That non-conductive coating on the inner 50% of two of the three pins is a safety feature. Little fingers (and other items) can slip into the gap between the plug housing and the wall socket while the pins are still in contact with the socket's connectors, risking electric shock. By insulating the pins near to the plug body, fingers are going to touch that coating should they slip while withdrawing a live plug.

    I understand that in some European countries the household wall outlets do not have an associated ON/OFF switch, meaning it is the practice there to plug and unplug appliances while the socket is always going to be live.
  11. Dec 7, 2014 #10
    Yup, I understand the above mentioned. However, the technical specifications aren't giving me any information how thick the insulation material is and what's the insulation material?

    Does anyone happens to know what's the insulating material? I tried googling but there are several types of plastics being used which are

    - urea formaldehyde
    - phenol-formaldehyde
    - Melamine formaldehyde?

    If this is the case, can I use any of the above but provided that they do the samee thing?
  12. Dec 7, 2014 #11
    Another curious thing is about the current carrying capacity!

    What I've found out about the current carrying capacity is about cables (conductors') sizes. Is there such thing about finding it current carrying capacity on a solid copper conductor?
  13. Dec 7, 2014 #12


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    The reason is, I think that without the insulating section, when you try to pull the plug out of the socket, it is possible to wrap your fingers round underneath (Particularly children) and touch the live pins before they disconnect from the socket. For decades, the plugs had pins which were brass over the whole length. (All UK wiring is 240V, remember)

    The British square pin plug and socket arrangement is pretty good, mechanically - especially those from reputable manufacturers and will supply 13A continuously without getting more than 'just warm'. They all have an internal fuse and were designed to fit in with the 'Ring Main' system. (See this wiki link). We have ad a few 'discussions' on PF about the UK Ring Main system and some of our US contributors seem to take against it. There are a few disadvantages (as that wiki link says) but the overall domestic supply situation is actually pretty good and the standard of wiring and pluggery compares well with most of the rest of the World. It certainly saves on copper cable if you want a flexible arrangement with a good selection of sockets around the house.
    Nowadays, all (?) appliances come with moulded plugs so there is little risk that the plug can be badly assembled by 'amateurs' and they mostly survive to the end of life of the device.
    For some reason, non-UK engineers and mere mortals seem to struggle with the concept of the Ring Main. ('nuff said)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook