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Discuss can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW shower in the Electrical Forum area at ElectrciansForums.co.uk.

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  1. mikejd
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    mikejd Guest

    Hi I have two 6mm csa cables in the loft each going back to a separate 30A mcb in the CU. One is redundant, the other goes to a broken 8.5kW shower. I want to fit a new 9.5kW shower and would like to join both 6mm cables together at a 50A dpst shower switch, then run a short length of 10mm csa cable from the switch to the shower. Can anyone see a problem with doing this. Both 6mm cables are approx same length (12m), there is a RCD in the CU.
    Thanks
     
  2. SPARTYKUS
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    SPARTYKUS Trusted Advisor

    Location:
    Shropshire
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    what do you think mikejd?

    what can you see as the down sides to doing it this way....if any?
     
  3. mechelec
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    mechelec Electrician's Arms

    Location:
    Here
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Sounds great. You could always connect a fan to the circuit as well ; )
     
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  4. Murdoch
    Online

    Murdoch Electrician's Arms

    Location:
    Woking
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Good luck connecting 2 x 6mm cables in the isolator
     
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  5. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    get a 8.5kWatt shower instead. use 1 6mm and keep insulation out of the way. sorted.
     
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  6. Plonker 3
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    Plonker 3 Guest

    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    What he said

    And what he said.
     
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  7. Pete999
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    Pete999 Trusted Advisor

    Top Poster Of Month

    Location:
    Northampton
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    The mind boggles
     
  8. sparks1234
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    sparks1234 Electrician's Arms

    Location:
    Hertford
    Business Name:
    A2electrical.co.uk
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    What ya gonna put on your test sheets?
     
  9. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    and after further consideration, boggles again.
     
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  10. Specialist
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    Specialist Electrician's Arms

    Location:
    South Wales
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Doubt he'd be doing test sheets mate, he's a teacher not a sparky.
     
  11. sparks1234
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    sparks1234 Electrician's Arms

    Location:
    Hertford
    Business Name:
    A2electrical.co.uk
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Thinking about that, could always put it down as a ring
     
  12. amlu
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    amlu Trusted Advisor

    Location:
    wild east london
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    2x 6mm cables wont fit into 50a switch terminals. better get a small din rail equipped enclosure and join them on a 100a isolator.
     
  13. Geoffsd
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    Geoffsd Guest

    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Just a thought -

    9500 / 240 = 39.6A
     
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  14. sparks1234
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    sparks1234 Electrician's Arms

    Location:
    Hertford
    Business Name:
    A2electrical.co.uk
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    bet a 5WW could get em in, cut some of them pesky cores out
     
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  15. markc123
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    markc123 Trusted Advisor

    Location:
    Yorkshire.
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    This is no word of a lie .... I was once presented by a receptionist of a log-cabin park a piece of A4 lined paper that said ....

    Circuits :
    Sockets - Passed
    Lights - Passed
    Cooker - Passed

    Appliances :
    Fridge - Passed
    TV - Passed
    Kettle - Passed
    Microwave - Passed
    Toaster - Passed

    That was when i was working for my dad before he retired, towards the end of my apprentership - The receptionist had apparantly told him if he wants to rent his log cabin out during the summer he's going to have to get an electrical test done on it - and he presented her with that lol. That's when we were called on his behalf.

    Maybe the OP has something similar in mind, lol.
     
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  16. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    perfectly OK till the insulation monkeys smother the cable.
     
  17. mikejd
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    mikejd Guest

    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Thanks for the reply. Please help, I cant see the down side. Each of the two 6mm cables have individual 30A mcb's in the CU. The two 6mm cables fit easily into the 50A isolator switch. If somehow one cable became damaged in the future, then the current draw down the other cable would trip the other 30mcb.
    What have I missed?
     
  18. sparks1234
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    sparks1234 Electrician's Arms

    Location:
    Hertford
    Business Name:
    A2electrical.co.uk
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    As Tele said, if it was a short run, no insulation you might get away with one cable on the limit but chuck some fluffy stuff on it and start the derating
     
  19. Alex Ramage
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    Alex Ramage EF Member

    Location:
    Edinburgh
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    :rolleyes4::rolleyes4:
    Missed? Poor practice, non standard circuit/cable size, how to test it correctly not to mention the embarrassment of allowing any other electrical professional or inspection authority the satisfaction of outing your handy work. No argument you offer can excuse this as an electrical installation. Installation certificate would be interesting. Would you be so good as to forward us a copy?
     
  20. Archy Styrigg
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    Archy Styrigg Electrician's Arms

    Location:
    Manchester
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Numerous regulations which you need to comply with.
    They can easily be found in the latest edition of BS7671.
     
  21. Sintra
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    Sintra The Innkeeper Staff Member

    Location:
    Belfast/London
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Mate you can't put the cables on separate MCB's end off. You need to read the part in bs7671 regarding conductors in parallel.
     
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  22. mikejd
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    mikejd Guest

    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    But the (40A) current is shared down two 6mm cables (approx 20A down each). And each 6mm cable has its own 30A mcb back in the CU. From the 50A isolator pull switch near shower, where they join, the single cable to the shower is then 10mm. I cant see any over loading / overheating at all. Am I still missing something here.

    Except for failure to comply with regulations why would this not be safe?
    Any advice really appreciated
    Thanks
     
  23. gazj82
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    gazj82 Regular EF Member

    Location:
    Cambs
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    I agree, but should we have to comply with every idiot that might come along and do something like this. The insulation monkeys should be educated, before stuffing the loft full of the stuff!

    EDIT: Just read this again, I don't think you was implying we should :oops:
     
  24. jackhammerJIM
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    jackhammerJIM Regular EF Member

    Location:
    north yorks
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    2 separate supplies joined together .

    your having a laugh mate .

    DIY FORUM
     
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  25. Sintra
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    Sintra The Innkeeper Staff Member

    Location:
    Belfast/London
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    If you think a 30A mcb will trip out at 30A you are mistaken.
     
  26. Murdoch
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    Murdoch Electrician's Arms

    Location:
    Woking
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    What training/competence/test kit do you have?
     
  27. Sintra
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    Sintra The Innkeeper Staff Member

    Location:
    Belfast/London
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Op can I ask your qualifications please as this is basic stuff.
     
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  28. Plonker 3
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    Plonker 3 Guest

    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    I just think we need to leave this thread alone, no matter what we tell the OP it just seems to fall on deaf ears.

    I want to know who is going to get here first Glenn or Biff.
     
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  29. Murdoch
    Online

    Murdoch Electrician's Arms

    Location:
    Woking
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    This thread is the classic example of how Dan needs to change the forum. If the OP is unwilling to attempt to answer some of the questions he should be put on a ban until he does.
     
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  30. Specialist
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    Specialist Electrician's Arms

    Location:
    South Wales
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    According to his profile he's a teacher, hope he knows a bloody sight more about that than he does about electrics .
     
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  31. hasel5
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    hasel5 Electrician's Arms

    Location:
    Southampton
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Oh dear oh dear what a mess
     
  32. Wiresandthings
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    Wiresandthings DIY

    Location:
    MELKSHAM
    Just do yourself a favour mate and call and electrician! What your planning on embarking on is just plain stupid! Plenty of safe solutions to this problem!
     
  33. Alex Ramage
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    Alex Ramage EF Member

    Location:
    Edinburgh
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    OK buddy. Jokes over. You've had your fun now toddle off to some other trades website and wind them up
     
  34. jimjimjim
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    jimjimjim Regular EF Member

    Location:
    Yorkshire
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    My god, i didn't realise until half way through he was talking about two seperate breakers bahahahahah. This has to be a wind up.

    Jim
     
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  35. Guest55
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    Guest55 Guest

    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    theres only 1 poster i can think of that covers this........


    GFP.png
     
  36. Murdoch
    Online

    Murdoch Electrician's Arms

    Location:
    Woking
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Fingers crossed he's not a science/Physics teacher!
     
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  37. MUFC1999
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    MUFC1999 Guest

    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Unfortunately this will not stop him doing what he thinks is OK.

    Any basic understanding of the regs tells you this can't be done.
     
  38. mikejd
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    mikejd Guest

    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Thanks to you who have replied genuinely to my question, without feeling the need to result to sarcasm. No I am not a qualified electrician and never claimed to be but I am both a physics graduate and electronics engineer. I never doubted that regs would not allow this to be done, though from an electrical theory perspective it is perfectly feasible, Its a shame very few replies seemed to go beyond 'you cant do it as it breaks the regs' and considered the theoretical reasons why...of which there are few.
    Thanks again
     
  39. amlu
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    amlu Trusted Advisor

    Location:
    wild east london
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    replace individual mcb for each cable for 1x mcb for both cables. 32a should do the job. connect both cables to it, then join them at other end and attach to a length of 10mm going into the shower.
     
  40. wirepuller
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    wirepuller Trusted Advisor

    Location:
    south uk
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    The main reason being that supplying a circuit with two separate MCB's creates problems with isolation. Another reason is that two MCB's in parallel are an unknown quantity for short circuit and overload protection. You cant do it. End of.
     
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  41. micknew
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    micknew Electrician's Arms

    Location:
    Kent
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Nobody went into it because its such a stupid dangerous thing to do, get a sparks in.
     
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  42. Alex Ramage
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    Alex Ramage EF Member

    Location:
    Edinburgh
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Figured as much. You need a physics nerd website my son. One where your theories can be appreciated and discussed out with the confines of the regulations and common sense which shackle us mere mortal sparks
     
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  43. Engineer54
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    Engineer54 Guest

    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Also further to ''amlu's'' post #39 There are very strict requirements for ''Parallel'' supply wiring, among others, one very important requirement, being that Both cables must be of exactly the same length and follow the same route. I doubt very much if this will be the case in your situation from what you have told us.

    And no you're thoughts on a dual supply from 2 separate OCPD is not perfectly feasible from a theory perspective. Until you know the theory behind the design of a circuit, it's advisable you don't make speculative claims that can't be substantiated!! ....So Again, DONT DO IT!!!
     
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  44. PEG
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    PEG Trusted Advisor

    Location:
    Manchester
    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    I knew if i waited long enough,retribution for my unacceptable 1979 excuse for not returning my physics homework,would be forthcoming...take that teacher...on a lighter note,just because a method is a possibility,does not mean there are not other reasons why it should not be attempted. These reasons are sometimes practical,and sometimes dictated by regulation,now and again it is both. Imagine if someone posted on a serious driving forum,if it was possible to drive around all day long,and just use the handbrake to stop the vehicle. You could,with care,do this,but is this sensible? Now off you go...DON'T RUN IN THE CORRIDOR!:goofy:
     
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  45. Geordie Spark
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    Geordie Spark Trusted Advisor

    Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

    Aye .. and one of them electric body driers as well and don't forget the spur for the shed and outside light.
     
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