'Making up' a cooker unit from 45A switch and 13A socket.

Discussion in 'Electricians' Talk' started by Brian Frost, Mar 18, 2019.

  1. Brian Frost

    Brian Frost New Member

    Hi, I'm planning to use a switch socket range that doesn't include a cooker unit. The cooker feed can be nicely dealt with by their 45A DP switch but I'd still like a single socket. My plan was to use a dual-gang back box to house the DP switch plus a 13A single socket. When I wire the socket to the output of the DP switch, the conductors will be within the back box and about 100mm long. Can I use 2.5mm conductors or must I use 4mm?
    TIA for your comments. Brian.
     
  2. seneca

    seneca Screwfix Select

    2.5mm will be fine, it's a single socket so the most you can draw from it is 13 amps so well within range.
     
    Brian Frost likes this.
  3. Brian Frost

    Brian Frost New Member

    Thanks Seneca.
     
  4. Alan sherriff

    Alan sherriff Member

    As the cooker cicuit is backed up via a possible 40 amp cicuit breaker does the smaller cable not capable of carrying in exstreams of 40 amp
    Come under the 3 metre rule as overload is protected via fuse in appliance plug top and short cicuit protection via circuit
    does this come under the 3 metre rule as overload is satisfied by the fuse in the plug top and short circuit protection via circuit breaker
    But the fuse or circuit breaker will protect the cooker cable but the 2.5 is smaller than the 32 or 40 amp fuse and any change in cable size would warrant fussing down . The cooker cable should feed the cooker outlet only as what is planned to do you could wire single sockets of cooker cable without fusing ??
     
  5. Coloumb

    Coloumb Well-Known Member

    The idea is the 2.5mm only carries the current needed for the plug so will not need overload protection. Fault current protection "should" be provided by the breaker. An adiabatic equation would prove this.

    None of this comes under the so called "three meter rule". There is no three meter rule.
     
  6. dobbie

    dobbie Well-Known Member

    It comes under Regulation number 433.3.1 (ii)
     
  7. Alan sherriff

    Alan sherriff Member

    Agreed but shower and cooker and Imersion heater should be on there own cicuit could now say that a spur none fused is permissible of these circuits to a twin socket outlet is o/k
     
  8. Coloumb

    Coloumb Well-Known Member

    I'm pretty sure that's like a "best practice" sort of thing from the OSG. No actual reg, but I would have to check. Maybe someone here will know.
     
  9. dobbie

    dobbie Well-Known Member

    Agree with you,I would not spur off any of those circuits either as I would deem it as bad practice,but if it was done it would need to comply with 433.3.1((ii)
     
  10. Coloumb

    Coloumb Well-Known Member

    I don't think your allowed to fit a socket to a ctt. with a 5s disconnection time, usually a distribution ctt. using a fuse rather than a MCB.
     
  11. Coloumb

    Coloumb Well-Known Member

    ^not a problem 4 me mate:)
     
  12. seneca

    seneca Screwfix Select

    It's not a "spur" as such is it, spurs come from ring circuits, this is a radial! Also the conductors will only be about 4 inches long and will be within the same enclosure so where's the problem?
     
  13. dobbie

    dobbie Well-Known Member

    I said it can be done if the regulation I quoted is adhered to,but said I would not do it.
     
  14. Alan sherriff

    Alan sherriff Member

    Yes I would agree as it not going to adhere to fault protection as to say if a light is to be fitted of any circuit say a power radial circuit then a fcu is installed as a reduction in csa occours unless you wire the light circuit in the same sized cable
     
  15. seneca

    seneca Screwfix Select

    So what difference if a fused spur or as in this case a 13 amp plug & socket?
     
  16. Alan sherriff

    Alan sherriff Member

    As said before the 5 sec dis time would not satisfy the .4 sec dis time for socket circuit as 5 sec allowed for protection device above 32 amps ???
     
  17. Comlec

    Comlec Well-Known Member

    Another thread where the answer is given in post #2 and accepted by the OP in post #3, problem solved thanks to speedy advice from the wise Mr @seneca

    Now followed by the usual discussion of no interest to anyone, with the possible exception of @Risteard who will be along in a few pages to put us all right
     
    DIYperson and Bazza-spark like this.
  18. Brian Frost

    Brian Frost New Member

    lol - yes, hilarious. Some have a point though, it might be better to use the 13A ring rather than the cooker feed, especially as I've an 8kW induction hob plus 3kW oven.
     
    Comlec likes this.
  19. peter palmer

    peter palmer Well-Known Member

    Thought all circuits were 0.4s disconnection times nowadays, only distribution ones could be 5s.
     
    seneca likes this.
  20. Coloumb

    Coloumb Well-Known Member

    Supplies to fixed equipment can also still be 5s, if you can wangle it to fit a fuse and no rcd. Who would do that these days?
     
    seneca likes this.

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