MCB Question

Discussion in 'Electricians' Talk' started by DanielQ, Oct 10, 2018.

  1. DanielQ

    DanielQ Member

    In there any issue in having a 40amp MCB with two different sizes of wires?

    MCB -> 10mm cable -> 20amp fused switch -> Induction Hob

    Same MCB -> 4mm cable -> 20amp fused switch -> Pyrolitic Oven

  2. EZ Tutty

    EZ Tutty New Member

    If I've understood your question correctly, getting a 10mm Cable and a 4mm cable in the same MCB is going to be a nightmare.

    Ideally I'd take the 10mm to some sort of junction box (maybe a twin cooker outlet) and split the 10mm into 2x6.0mm cables** to the 20a Switched FCU's.
    Last edited: Oct 10, 2018
  3. dobbie

    dobbie Well-Known Member

    Just have two circuits,a 40a mcb is too big for 4mm cable and you are going to have fun and games trying to put 10 mils in a 20a double pole switch.

    I think it is time you enlisted some help.
  4. DanielQ

    DanielQ Member

    Would it be better to have the 4mm cable from the oven in the 32a MCB for the kitchen sockets. Any issue with having 3 cables in one?
  5. Alan sherriff

    Alan sherriff Member

    The circuit breaker 40 amp with 4m/m cable would not give overload protection only the 6 mill would have overload protection. Can you not shuffle circuit breakers around and put the 4 mill on a 32 amp circuit breaker or lower depending on the fixed load of the pyrolitic oven
    Check full load first of the oven to check if the 4 mill is sufficient in the first place
    37 amps top current for cable without other detracting factors
  6. DanielQ

    DanielQ Member

    So, would it be better how I said in my previous post?
  7. Alan sherriff

    Alan sherriff Member

    Yes I just thought as the 4 mill has been brought back to the board it would be better on separate breakers would for each dedicated circuit and avoid junction box either way would do the job
  8. DanielQ

    DanielQ Member

    Thank you Alan.

    I would prefer to have it in a different circuit but I'm running out of space for more MCBs in the CU.
  9. Alan sherriff

    Alan sherriff Member

  10. Alan sherriff

    Alan sherriff Member

    You must be tight as usually the bus bar can be extended or double up lighting circuit if on separate breakers and insert new cicuit breaker
  11. Magicspark

    Magicspark Active Member

    I can’t believe members are still trying to help the OP out. He is obviously clueless and dangerous..... Read some of his other posts/threads.
  12. DanielQ

    DanielQ Member

    The CU has 10MCBs and no space for extending.

    The option of having 10mm and 4mm in the same breaker is discarded So.

    The options are:

    1. Oven in the same MCB as the kitchen sockets .

    2. Put the upstairs and downstairs lights in 1 MCB instead of 2.

    3. Currently I have the 300w Bathroom Underfloor Heating with the combi boiler in 1 MCB and a separate MCB for the fire alarms. Merge the two.

    Thank you
  13. retiredsparks

    retiredsparks Well-Known Member

    Hence my original statement.
    He seems to think that because he is 'short of money''s ok to mess about with a discipline he has no training in ......knowledge of or skills in.
    Not sure which channel Sesame Street is on in his area......:rolleyes:
    Magicspark likes this.
  14. DanielQ

    DanielQ Member

    I am trying to do my best to finish a refurbishment that has already taken a year and a half of my life.

    I try to do things safe, plan things ahead, check things 5 times, etc.

    It would be great to have a professional sorting everything out for me.

    My partner and I have been living in a building site for over a year without even a kitchen, at this point your priorities change.

    I know I am not the smartest person in the planet but I am willing to put the time and effort to get things done. You are free to just don't help or tell me that I am dangerous, it is up to you.
  15. retiredsparks

    retiredsparks Well-Known Member

    You are dangerous.
    My helpful advice is to stop playing with electrics.
    (from your MO, I also assume you will also be playing with gas and plumbing ?)
    I suspect you have no test gear and cannot confirm the safety of what you have done/botched.
    You are in breach of Part P of the Building Regulations ...WHICH...IS A CRIMINAL OFFENCE.
    I don't blame you for improving your home....but there are some things which you should NOT be messing with.
    You have taken on a project which appears too large for your skills and finances.
    Am I being too harsh ?
    Magicspark, sparky steve and Jord86 like this.
  16. Bazza-spark

    Bazza-spark Well-Known Member

    As previously stated, you are carrying out notifiable work that has not been notified and you are not qualified and do not have the appropriate equipment to test it.

    The questions you are asking give cause for concern and I am pretty sure you will not have all the correct bonding in place.

    We all understand you are trying to save money, but the is a point you must get a professional in to oversee the work at a minimum.

    Failing that, contact DIY SOS!

    Kind regards
    sparky steve likes this.
  17. Jord86

    Jord86 Well-Known Member

    Without sticking the knife into you, better for your house to take up another year and a half of your life than TAKE your life.

    Look, it's different to not know what you're doing with painting a wall, who cares, not life threatening in the slightest, but what you're doing is ludicrous in the extreme, forget breaking the law as RS said, you're asking for trouble messing with things you don't have any experience of, let alone if you grasp a basic understanding of it. I'm a carpenter who regularly works alongside electricians and observes their workings, but I'm happy to admit I'm absolutely clueless when it comes to the trade, as such I would never dream of having anything to do with it, for my own sake and others.

    I understand more than you know about living with a shell for a kitchen, no floor, half the joists missing/rotten, no heating, where the microwave plugged in in the living room is the only means of cooking food etc, but you really need to stop thinking of the financial implications of getting an electrician in, and start thinking about a safe home for you and your partner to live in.
  18. DanielQ

    DanielQ Member

    Yes, you are being a ...!! but I respect your opinion.

    I researched a lot about plumbing and gas but I have not touched myself.

    Project too big? sure...The Home Report was a joke and to rectify all the issues is taken longer than expected.

    My skills...basic DIY but I am able too learn and as you already realised, I am doing my best.

    I'm not completely idiot...I work as a network Engineer for a local authority and English is my second language. So, I can't help with electric but with networking, or where to on holiday in Spain, I am the man.
  19. Jord86

    Jord86 Well-Known Member

    Don't you think if English is your second language then that's even more of a reason to call a professional in? You're really not helping your case here at all.
  20. DanielQ

    DanielQ Member

    Could you please make your point? I don't get it.

Share This Page