Just to check I'm doing this right?

Discussion in 'Electricians' Talk' started by Tangoman, Aug 1, 2004.

  1. Tangoman

    Tangoman Well-Known Member

    Hi guys,

    got myself a single electric oven - rated at 4.1kW /240V
    Already installed cooker outlet on 6mm cable run, taking a fused spur off this for the hob.
    Was planning to fit a 20A MCB on the circuit, and connect the oven with 2.5mm heat resistant flex which is I understand rated to 6kW.

    However, the manufacturer's instructions with the oven seem to suggest use of a 6mm cable - "to connect the oven to the electrical supply". Are they referring to the circuit cable used? or do they really mean that my 2.5mm is insufficient - if so why is 2.5mm insufficient for 4.1kW which is only 17A?

    Cheers,

    Tango
     
  2. andyboy

    andyboy New Member

    you checked diversity ?
     
  3. Tangoman

    Tangoman Well-Known Member

    By diversity - I take it we are talking diversity on the circuit, rather than on the house.
    On the house - yes and there's no problem - replacing higher rated appliance with lower anyway.

    On the circuit - no need - Hob takes 3A (gas) and Oven 17A max so 20A breaker easily covers.

    Question still on the wire though - anybody any idea why the manufacturer is stating 6mm cable? p.s. It's German!

    Tango
     
  4. andyboy

    andyboy New Member

    1st 10A plus 30% of remainder, + 5A if fitted with socket outlet on control.
    Always fit bigger cable as you may or someone else may fit a bigger oven in future.
     
  5. Tangoman

    Tangoman Well-Known Member

    I think that you are misreading my post.

    I'm referring not to the fixed wiring which is 6mm, but the connection cable to the oven (which is supplied without). Diversity does not apply here - the oven is a 17A model and thus the only device which will be drawing current through this cable.
     
  6. plugwash

    plugwash New Member

    its called sh*y instructions

    also the maker may assume that you are goign to put it on the same cuircuit as a hob in which chase it would be normal to use cable rated to match the breaker

    [Edited by: Forum Moderator]
     
  7. Tangoman

    Tangoman Well-Known Member

    Good point plugwash - hadn't thought of that (the leccy hob point that is).

    Tango
     
  8. sparksrus2000

    sparksrus2000 New Member

    Reducing the connection of the oven to 2.5mm is also reducing the csa of the cpc to 1.5mm which under fault conditions could affect the disconnection time or actual loop impedance
     
  9. Tangoman

    Tangoman Well-Known Member

    I had thought of that sparksrus.

    However, checked and the cpc is also 2.5mm.

    Tango
     
  10. The Trician

    The Trician New Member

    Hi Tango,

    Had a similar problem recently. 900mm range cooker with 3KW electric oven and 5 gas burners.
    Accomapnying manual/destructions rated the appliance at 5.1KW total!

    Trouble was, that there wasn't a seperate figure given for the oven only.

    Ended up ringing manufacturer/supplier who told me to use 2.5 heat-resistant since the oven bit only took 16A.
    Had already run a 6.00mm to a cooker connection unit so I just asked for an assurance from their tec dept that if I ran a 2.5 3 core from this to the oven terminals and the 2.5 burnt off the terminals, then they'd sort it under the warranty.

    Got an emphatic 'YES' so went ahead. 12 weeks on and no probs so far.

    TT
     

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