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New boiler being installed - Wiring new fused connection

Discussion in 'Electrics UK' started by LiGhTfasT, 7 Feb 2015.

  1. LiGhTfasT

    LiGhTfasT

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    Hi, I'm having a new boiler installed in a new location the other side of the house. The current setup is an old convential boiler with pump/diverter valves etc.

    The current circuit is a 6a MCB feeding the boiler / burglar alarm. Coming from the consumer unit is 2x 1.5mm cables on that MCB feeding a fused connection for the alarm and the other cable wired straight to the boiler wiring with no FCU that I can see at all which isnt good. At this point the wiring goes off to thermostats and pumps and will be a big task to identify so the plan is to get rid of the lot at the consumer unit.

    I have an easy route to the new boiler location (under the floor) and a roll of 2.5mm T+E, would there be any issue terminating this to the 6a MCB other than being uncommon? I would also replace the wiring to the FCU for the alarm with 2.5.

    Thanks
     
  2. Iggifer

    Iggifer

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    Irrespective of any other issues, there is absolutely no point using 2.5mm.

    1mm would be fine. 1.5mm would be more than enough, 2.5 is ridiculous.

    Why not just add a spur either above the CU or where the existing boiler is and then just run the new cable from there?
     
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  4. deadshort

    deadshort

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    Hi, yes 2.5mm would be fine and as you already have some even better ! It would be an issue if you wanted to use a lower gauge cable on a larger breaker! 2.5mm will handle 27a

    so, no problem with 6a !


    Kind regards,


    ds
     
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  5. LiGhTfasT

    LiGhTfasT

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    I already have a good 20m of 2.5 on a roll in the garage so will cost me nothing and will have no other use for it. I didnt want to put it on a spur off the kitchen ring since it already has its own circuit. Thought it may also come in handy one day if needed with a bigger MCB.

    Thanks for the replies :D
     
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  7. JohnW2

    JohnW2

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    ...except that 2.5mm² is what the OP has!
    Unnecessarily large, sure - but as deadshort has said, not 'ridiculous', particularly if that's what one has! You're right that 1.5mm² would be more than adequate. So, electrically speaking, would be 1mm² - but, unless you could successfully argue that a boiler counts as 'lighting', it would probably not be compliant with regs!

    Kind Regards, John
     
  8. DIYnot Local

    DIYnot Local

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