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Cable diameter for long distance run

Discussion in 'Electrics UK' started by RGi, 11 Oct 2018.

  1. RGi

    RGi

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    I'm looking to make an extension lead of over 60m to run a well pump of of the generator after storms or other power cuts. It needs to run the pump which is rated at 2400 Watts. What diameter cable is needed for this to allow for power loss over distance.
     
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  3. flameport

    flameport

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    2.5mm² 3 core flex. 3183TRS or similar.
     
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  4. RGi

    RGi

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    Thanx! It would be great to know how to work it out so I don't have to ask again?
     
  5. oldbutnotdead

    oldbutnotdead

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    Does the pump not need to run in normal (ie not power cut) circumstances? 2.5mm TRS or SWA would do the job (but SWA isn't exactly an extension cable)- might be better getting one of those cheap site gennies from ebay and not having a 60m cable run
     
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  6. RGi

    RGi

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    Thanx Oldbutnotdead. The pump runs of a buried sheilded mains, but in outages it runs of a genie and 60 m is the closest it can get.
     
  7. oldbutnotdead

    oldbutnotdead

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    Fair does. For future, you're looking at current carrying capacity of the cable and critically volt drop. This here calculator https://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html will do the basics
     
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  8. EFLImpudence

    EFLImpudence

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    I can't get TLC's calculator to give a result

    although I can do it manually with a satisfactory resut of 2.5mm² as flameport said.
     
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  9. ban-all-sheds

    ban-all-sheds

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    Shouldn't the starting current of the pump be considered?
     
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  11. SimonH2

    SimonH2

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    Do you have access to the supply end of the normal power cable for the pump ?
    If so, then you could fit a change over switch there and (say) a BS4343 (aka Commando) power inlet. That would avoid the need to run out a long extension lead every time you need it.
     
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  12. RGi

    RGi

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    I had a bit of difficulty with it myself. Any chance of the formula or a link to it?
     
  13. RGi

    RGi

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    I don't know, should it?
     
  14. RGi

    RGi

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    Good idea but the generator is in a different location unfortunately.
     
  15. ban-all-sheds

    ban-all-sheds

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    What problem(s) were you having?
     
  16. ban-all-sheds

    ban-all-sheds

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    Yes, because if it is high in comparison to the steady-state load you use to size the cable the voltage drop when it tries to start my be too high, and it might not start properly.
     
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  17. RGi

    RGi

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    Last edited: 17 Oct 2018
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