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Installing new oven ring main without making a mess. Possible?

Discussion in 'Electrics UK' started by MugabesDeadCat, 10 Nov 2019.

  1. MugabesDeadCat

    MugabesDeadCat

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    Hi,

    Our kitchen has a 20A ring main for our double oven. Looking at buying a new double oven and they're all 32A. The existing cable appears to come out the consumer unit, up the wall, into the ceiling, along a joist and then back in the wall and goes down to the oven.

    The walls are solid and the cable is chased into it. It's a straight line from the consumer unit under the stairs to the oven, albeit up the wall, over the ceiling and down the opposite wall.

    My question is, if this isn't 6mm² cable, how much mess and destruction would installing a new cable be? Am I going to have to accept the walls will need chasing and the floorboards upstairs lifting?

    Thanks
     
    Last edited: 10 Nov 2019
  2. terryplumb

    terryplumb

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    Cables don't have to be buried in walls ,they can be surface mounted ,or in trunking. Only a site visit would reveal the least disruptive route for a cable installation.
     
  3. flameport

    flameport

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    A 20A ring would be very unusual.
    A 20A radial is rather more likely.

    How many cables are there at the consumer unit and oven connector? A ring would have 2, a radial only 1.

    What size is the existing cable?

    Is the circuit only for the oven, or does it supply other items as well?
     
  4. winston1

    winston1

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    It doesn’t need to be 6mm cable, 4mm will do.

    If the cable is less than this then yes there will be disruption. Maybe, just maybe, if the existing cable is in conduit you may be able to use it to pull a larger one through.
     
  5. MugabesDeadCat

    MugabesDeadCat

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    Ah sorry, not sure on the correct terminology. It's a cable direct from the consumer unit to the oven, no other appliances served from it. It has a 20A breaker on the consumer unit for it. Is that a radial?

    So even if we opt for a 5.9kW oven, if it's 4mm cable, it should be ok?

    Existing cable is clipped to the joist. I know this because we recently pulled the kitchen ceiling out and reboarded it and you could see it.
     
  6. EFLImpudence

    EFLImpudence

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    All circuits are radials - except socket ring circuits.


    5.9kW @ 240V is 24.6 Amps.

    So, 2.5mm² cable would be alright - as long as it does not run through thermal insulation.
    If it doesn't you could change the MCB to 25A if they are made for your consumer unit.

    There are various ways of deciding that what you have already might be alright for your oven -
    but you need to tell us what size the cable is and that it is not in any thermal insulation.
     
  7. Taylortwocities

    Taylortwocities

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    Pity you didn’t plan the whole project and make provision, while the ceiling was down.
    But that’s no helpful.… sounds like you might be ok, from EFLI’s post above.
     
  8. MugabesDeadCat

    MugabesDeadCat

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    Yeah, the oven was working ok then.

    Could always pull it back out mind
     
  9. MugabesDeadCat

    MugabesDeadCat

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    No thermal insulation, it's chased into the wall and clipped onto a joist.

    I do know it's heavier cable than what the 13A sockets have but unsure on the size. It's really stiff whatever it is. See attached photo for back of switch on wall.
     

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  10. winston1

    winston1

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    Well the next size up is 4mm, then 6mm. Either is OK.
     
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  11. EFLImpudence

    EFLImpudence

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    Yes, looks like it. Maybe someone fitted the 20A MCB for the present oven and it is a 'standard' cooker circuit.

    So, 32A MCB will be alright if you have one fitted.
    The oven can't draw more than its 24.6A anyway. It will be less than that as not all on at once.


    Just one more thing - do you have a socket in the cooker switch?
     
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  12. EFLImpudence

    EFLImpudence

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    Ignore that - looked at the picture again.
     
  13. MugabesDeadCat

    MugabesDeadCat

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    Nah, there's a socket on the induction hob switch. But that's on a separate breaker
     
  14. EFLImpudence

    EFLImpudence

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    That doesn't count.
     
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  15. MugabesDeadCat

    MugabesDeadCat

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    Do you only ever fit a breaker to suit the rating of the appliance? I.e. current oven is 4.4kW, which I believe is about 18A, so you fit a 20A breaker
     
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