Why?

Discussion in 'Electricians' Talk' started by 2 wheeled ant, Aug 5, 2008.

  1. 2 wheeled ant

    2 wheeled ant New Member

    Hi lads & lasses been a while,

    Had a spare few moments & reading some past topics, needed a laugh as low!


    Why when feeding cooker & hood of same 6mm circuit you say the feed to FCU from CCU for hood also has to be in 6mm?
    Same applies to say Dual box behind cooker for fan oven (uns spur) & halogen hob (cooker outlet)

    2.5mm ok, your covered for overload with 3amp fuse & fault 100s amps on 32a MCB

    Why 6mm

    Ant
     
  2. state-it

    state-it New Member

    Because a lot of people only have a half-baked understanding of both theory and regs, 2 wheeler anty person.
     
  3. joinerjohn

    joinerjohn New Member

    Someone correct me if I'm wrong but, its the wiring thats protected. In essence your implying that it would be ok to extend this circuit in 2.5mm without further protection?
     
  4. sysparks

    sysparks New Member

    I think the point he is making is that the 2.5mm from the cooker panel may be fused at 32a on its way upto the spur, but so is a spur from a ring final. Which is deemed ok, because a double socket can only draw a max of 26amps at full load. So if its ok for that, then why not for this?
     
  5. MGW

    MGW Screwfix Select

    I do see problem 433.2.2 limits length of cable to 3 meters if fused at destination rather than source yet for some reason we are allowed a spur from a ring main where the fuse is at the socket.
    But there is nothing to say you are allowed more than 3 meters on a spur so maybe we are not and all spurs not originating from a fused unit should be limited to 3 meters but to do so would be a bit pedantic.
    The main problem is with 134.1.1 where the manufacturer instructs one to limit the current to lower limit to that of the existing MCB and if this is done then taking feeds to any other items may cause the MCB to trip this is common with split level where although a fused spur unit can feed oven the hob is too big for local fused spur unit and manufacture instructs one to fit a current limiting device which would be too small to feed both items.
    I think most electricians fit an over sized MCB and consider standalone units are no different to both split level units so should be OK. And to fit local consumer unit to split supplies is being pedantic.
    But problem arises when someone in future picks up on it and with all records now kept by the LABC not so easy to worm out of.
    Eric
     
  6. 2 wheeled ant

    2 wheeled ant New Member

    Someone correct me if I'm wrong but, its the wiring
    thats protected. In essence your implying that it
    would be ok to extend this circuit in 2.5mm without
    further protection?


    2.5mm cable is protected against fault by 32a mcb & against overload of hob by 3a fuse in FCU


    Ant
     

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