8.5kw shower cable

Discussion in 'Electricians' Talk' started by lvlouse, May 13, 2018.

  1. peter palmer

    peter palmer Well-Known Member

    If 6mm isn't suitable to be protected by a 40A MCB then whats the point of it? 4mm is happy sat on a 32A MCB so why use 6mm? unless someone can find an MCB in between 32A and 40A. For me I would protect a 6mm cooker or shower with a 40A breaker, especially as most mains units come with at least one one, for one thing it saves having a bucket full of unused 40A MCBs in the van.
     
  2. lvlouse

    lvlouse New Member

    Hello All,

    I feel like I have created an argument between various users which I have noticed happens time and time again in all of the posts I have read about showers. Although personally I believe 6mm would probably have been fine for the last 2m for an 8.5kw shower, I am not an electrician so i can't speak with any authority.

    Since there is no consensus that 6mm will do the job I have gone out and bought 5m of 10mm and swapped it out last night. Now I can rest easy knowing that the house wont burn down while i'm in the shower lol, bit dramatic but that sort of thing plays on my mind.

    thanks all for your input, tis very much apreciated, i can now let the fitters in to do my bathroom :)
     
    Heat likes this.
  3. seneca

    seneca Screwfix Select

    And that's probably where your real problems will start! :(
     
  4. lvlouse

    lvlouse New Member

    hehe, been there done that with the bedrooms to be honest. fortunately, the guys fitting the bathroom come highly recommended and have done very good jobs on my girlfriends parents house.
     
    seneca likes this.
  5. seneca

    seneca Screwfix Select

    Hope it all goes well for you mate.
     
  6. Heat

    Heat Active Member

    If 6mm can’t carry the power of 8.5 kw for 2 metres, then I think many houses will be wrong. :p
     
  7. Bazza-spark

    Bazza-spark Well-Known Member

    I know it is a fixed load, butI still would not have a 40A breaker on 6mm. End of.
     
  8. Risteard

    Risteard Well-Known Member

    Doesn't make you correct though.
     
  9. Bazza-spark

    Bazza-spark Well-Known Member

    Didn't say it can't carry it. I said the breaker was too big for 6mm cable rating.

    Kind regards
     
  10. Risteard

    Risteard Well-Known Member

    It's not too big if you know what you're talking about.
     
    Hollie likes this.
  11. Bazza-spark

    Bazza-spark Well-Known Member

    It doesn't make we wrong either. You want to protect 6mm with an oversized breaker that is your choice, not mine.
     
  12. Bazza-spark

    Bazza-spark Well-Known Member

    Electricity board trained, 45 years in the trade, ex MIET (Used to be MIEE but no longer exists), ex NICEIC QS, and never had to return to a job to put anything right. All still working fine, domestic (which I don't do a lot of these days), commercial and industrial (where I spend a lot of time) so I have a reasonable idea of what I am talking about.
     
    KIAB likes this.
  13. peter palmer

    peter palmer Well-Known Member

    How can anyone say 6mm cant carry 40 amps? depending on how its installed a 32A MCB might be oversized or it may be capable of carrying nearly 50 amps.
     
  14. Bazza-spark

    Bazza-spark Well-Known Member

    And it may not. The circuit was originally wired in 10mm. Why drop to 6mm because you dont want to buy a bit of 10mm. If the original design called for 10mm then stick with it or reassess the breaker size. I would not put 6mm on a 40A breaker given the info in the original post. You can please yourself, I wouldn't do it.

    Kind regards
     
  15. Hollie

    Hollie Member

    It's a fixed load so overload protection can be omitted. @Bazza-spark doesn't seem to be able to grasp the concept so I wouldn't take heed of his advice.
     
    Risteard likes this.
  16. Hollie

    Hollie Member

    why is it oversized?
     
  17. Coloumb

    Coloumb Well-Known Member

    Would you be ok to design and install such a ctt? 40a on 6mm?
     
  18. Bazza-spark

    Bazza-spark Well-Known Member

    Back again are you Lee
     
  19. Hollie

    Hollie Member

    If the cable has a sufficient CCC taking installation method etc into account. The 40A circuit breaker will be sufficient for fault protection, overload protection is not needed as its physically impossible to exceed the CCC of the cable. If I brought a fully populated CCU which had a 40A circuit breaker and the situation is as described in this post then I would have no qualms using it. This knowledge is the difference between someone who actually knows what they are doing and someone who thinks they do....@Bazza-spark, I hope you don't take offence. ;)
     
    Risteard likes this.
  20. fillyboy

    fillyboy Well-Known Member

    I know nothing about electrics, but I do love a good scrap between electricians on the old sparky forum.:)
     
    KIAB, Mike83, Heat and 1 other person like this.

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