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type of plastic use in UK home electrical fittings

Discussion in 'Electrical Engineering' started by mikey, Jun 9, 2009.

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  1. mikey

    mikey Guest

    What is the name of the brittle plastic used in UK electrical
    fittings for mains wall sockets and that sort of thing?

    I mean the plastic that a bit like the old bakelite.
  2. newshound

    newshound Guest

    That surprised me. My copy of Brydson's Plastic Materials (1975) says

    "when dry, casein is a good electrical insulator but is seriously affected
    by humid conditions. For this reason it can no longer compete with the many
    alternative plastics materials now available for electrical applications"


    "the once considerable application in knitting pins, pens and pencils is no
    longer of importance although a few propelling pencils were still being
    produced with casein barrels in 1964".

    That said, I don't know the answer, but I assume from the relative
    brittleness that high levels of filler are used.
  3. Ive been worrying about casein too, bit couldnt think what the plastic
    might be: melamine strikes a huge chords tho. I think that's the one.
    The cheap thermoset plastic..But I doubt bakelite is used any more at all.

    But I take your point that phenolic resin plastics are still around -
    typically for cheap PCB and the like.
  4. ABS is a thermo plastic. Not used where it gets hot.
  5. We were somewhere around Barstow, on the edge of the desert, when the
    drugs began to take hold. I remember "nightjar" <[email protected]<insert my surname
    here>> saying something like:
    Blimey, that'd be handy if you were locked in a room with no food.
  6. Steve Walker

    Steve Walker Guest

    Volex were certainly using Urea Fomaldehyde when I drew up the exploded
    diagrams and parts and materials lists for the 9000 range 20 years ago.

  7. Steve Firth

    Steve Firth Guest

    Errm, no.
  8. Steve Firth

    Steve Firth Guest


    The plastic component is usually a thermosetting resin, and as cheap as
    possible such as phenol-formaldehyde or phenol-melamine there will also
    be some sort of filler. Originally this was wood flour but modern
    plastics may use glass as either a fibre or microballoons.
  9. mikey

    mikey Guest

    It's interesting to see you mention alternative plastics.

    I asked the original question because the way the plastic broke
    when I snapped out some holes for the cable was damn crude and
    hard to control. I couldn't believe such hard to work plastic
    was ever used in a product!

    I was using some 16mm surface-mounted patresses to hold
    telephone socket faceplates in a very visible location. They had
    to look right.

    I swore next time I wouldn't use some bargain 50p patress
    because it was taking for ever and ever to get them right. Even
    them the irregular jagged holes left by the snap-outs were ugly.

    If had to pay several times the bargain price it would be good
    value for time saved! The result would be better too.
  10. mikey

    mikey Guest

    You might be thinking of the 55mm x 55mm (LJU1) or 67mm x 67mm
    (LJU2) phone socket.

    I was installing a couple of the larger 85mm x 85mm phone sockets
  11. Mains stuff really needs thermosetting plastics so it doesn't turn
    into cheese if something goes wrong and gets hot. Telecoms can use
    thermosoftening plastics, as there's not enough power there to
    overheat anything.
  12. PeterC

    PeterC Guest

    Yes, I found out the 'hard' (brittle?) way that, to some extent, the
    patress needs to be of better quality than the fitting. Even a slightly
    uneven wall can break a patress before the screws are done up.
    As for a cheap patress under a 40A pull-switch...!
  13. Newshound

    Newshound Guest

    I usually dremel the snap-lines before the final snap for just this reason
  14. Mike

    Mike Guest

    I bash it out with a screwdriver and then use a dremel abrasive band
    to clean up the edges if the break isn't clean.

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