Shower Pull Cord Burning Out

macca@90macca@90 Posts: 1,769
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Hi

We have replaced this 3 times in 9 years. Is this normal? :mad:

The casing went a bit yellow as though it has been overheating and this time some of the wires look as though they have melted a bit.

This can't be normal surely? :eek:

We do seem to have power surges sometimes as the Sky box goes funny. Is this connected do you think?

Comments

  • njpnjp Posts: 27,583
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    macca@90 wrote: »
    Hi

    We have replaced this 3 times in 9 years. Is this normal? :mad:

    The casing went a bit yellow as though it has been overheating and this time some of the wires look as though they have melted a bit.

    This can't be normal surely? :eek:

    We do seem to have power surges sometimes as the Sky box goes funny. Is this connected do you think?
    Overheating is the result of too much resistance in the circuit. Either the switch or cable are inadequately rated, or the connections to the switch weren't made properly - they need to be properly tightened.

    It won't have anything to do with your "power surges".
  • macca@90macca@90 Posts: 1,769
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    Thank you :)
  • CaxtonCaxton Posts: 28,881
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    I would suggest getting a qualified electrician to fix it asap, I second the reasons njp said above.
  • macca@90macca@90 Posts: 1,769
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    Thanks I will do :)
  • daveyfsdaveyfs Posts: 1,467
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    This is happening because the cables connecting to the switch have been annealed by the previous overheating - this causes the copper in the cable to soften, meaning that as the screw terminals on the new switch are tightened the copper 'flows' or flattens, never making a secure connection, so causing resistance and continued overheating.

    The only solution, if there's enough length in the cable, is to cut back to bright shiny (i.e. unaffected) copper and connect to a new switch. However if there's not enough length you'll have to put in a new run of cable - I'd never advise inserting joints into a high current circuit such as one serving a shower.
  • njpnjp Posts: 27,583
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    daveyfs wrote: »
    This is happening because the cables connecting to the switch have been annealed by the previous overheating - this causes the copper in the cable to soften, meaning that as the screw terminals on the new switch are tightened the copper 'flows' or flattens, never making a secure connection, so causing resistance and continued overheating.
    I'm happy to be corrected, but I'm not entirely convinced by this. Surely copper cable has already been annealed to make it more ductile, so what you describe is in fact a property of the cable prior to the first overheating event?

    Is there something special about this further annealing that makes the subsequent connections worse?
  • daveyfsdaveyfs Posts: 1,467
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    njp wrote: »
    I'm happy to be corrected, but I'm not entirely convinced by this. Surely copper cable has already been annealed to make it more ductile, so what you describe is in fact a property of the cable prior to the first overheating event?

    Is there something special about this further annealing that makes the subsequent connections worse?

    It is indeed annealed as part of the production process (i.e. soft drawn) to make it ductile, but the overheating in use anneals it further to a point where its softness is such that its not suitable for the sort of terminations its intended to be used with, which is what has happened in this case. Oxidation caused by heating also plays a part in increasing resistance.

    There's quite a good discussion about this in parts of this thread on the IET website.
  • MaxatoriaMaxatoria Posts: 17,980
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    If theres not much slack cable you could use a 60amp junction box to link a small bit of fresh cable into the pull switch but i'd get it properly checked out to make sure the cables/fuses etc are up to the job
  • Pull2OpenPull2Open Posts: 15,138
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    OP, get someone in. If its in the bathroom you may be subject to Part P of building regs!
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