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Why is it called a fused spur?

Discussion in 'Electrics UK' started by ericmark, 22 Aug 2021.

  1. ericmark

    ericmark

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    I would have called it a radial, a spur I think of some thing small sticking out from the main leg, when it can be over loaded unless we have some thing at the end to prevent it.

    I would assume it is linked to the phrase "ring final" if it is the final circuit then can't have another circuit coming from it. Or can we?

    More down to English than Electrics, but because called a fused spur I have a problem explaining why you can have more than one device on some spurs and not others. I was taught as an apprentice it was a radial when it came from a fuse to stop over load.
     
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  3. EFLImpudence

    EFLImpudence

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    I agree with you that the cable from an FCU (the so-called 'spur') is actually another circuit, by the definition of a circuit in BS7671.
    It's just that we call it 'a spur', whether fused or not.

    It is not as daft as calling the FCU itself a 'fused spur' - that's like calling a junction box an 'unfused spur'.
     
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  4. JohnW2

    JohnW2

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    Could it not be said that the definition is a bit ambiguous, in that the wiring downstream of the FCU is, at least in some senses, 'protected' by the upstream OPD?

    Particularly when cables upstream and downstream of the FCU are the same size (and the FCU essentially unnecessary), the bits downstream of the FCU are probably at least as 'protected' by the main OPD as by the FCU fuse (a 3A FCU on a 6A circuit, all in 1.0 or 1.5mm² cable, comes to mind).

    Those who attempt to argue that adding an FCU (and things supplied by it) to an existing circuit constitutes "adding a new circuit", hence notifiable in England, need to be reminded that even when, pre-2013, notification rules were far more demanding (as remains the case in Wales), adding an FCU (and things supplied by it) to an existing circuit was one of the few NON-notifiable things - so it clearly was not the intention that the relaxed notification requirements would reverse that.
    Agreed.

    Kind Regards, John
     
    Last edited: 22 Aug 2021
  5. EFLImpudence

    EFLImpudence

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    Yes, it is ambiguous.

    The definition is just arbitrary as two circuits can become one by putting them in the same MCB and vice versa.
     
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  7. JohnW2

    JohnW2

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    Quite so. As you imply, I think the problem is that the concept of 'a circuit' is essentially arbitrary.

    However, at risk of attracting flak, I would suggest that we "know roughly what they mean", and that includes 'knowing' that they didn't intend that what happens downstream of an FCU should be regarded as 'a circuit' (as in "new circuit") in the same sense as something which originated from the DB/CU.

    In this case, I don't think we can 'blame' them too much - since, other than by specifically excluding wiring downstream of an FCU, I'm not sure what 'better' they could have done.

    Kind Regards, John
     
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  8. ericmark

    ericmark

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    I can understand why we had Part P, kitchen fitters were going daft in the way they were wiring up kitchens. Followed by some of the antics of plumbers at the time. Number of tank thermostats with no earth and earth wire used as live is frighting.

    However my problem getting a replacement completion certificate from the council told it would take 4 months, and the fact the council themselves did not issue minor works or other paperwork for work completed in my mothers house, it seems they find the Part P law a nuisance, and have no intention in trying to police it.

    And it would have been so easy to say distribution unit instead of consumer unit maybe it was designed so people can get around it? The phase is "let the courts decide" but so unlikely it would ever go to court so unlikely they will ever decide.

    So is fitting a FCU a new circuit? Well if the wires already existed no, so if you extend a spur, then realise it does not comply, so add a fuse like this IMGP7387.jpg you have created a circuit but it is not new, it was part of a larger circuit in the past, and using the same fuse to supply a boiler would be no different to a plug, so it depends where the FCU is used as to if part of a circuit or not. The picture shows a grid plate with a 13 amp socket, switch, and 13 amp fuse holder doing same job as a FCU, but likely would not be called a FCU. It was used to reconnect some sockets in error made dead during a rewire. So parts of the circuit were from last century so not new.

    I was reading the new English guide for landlords issued by the government and the law it refers to, so
    and
    so
    interesting is what a day is
    so 28 days is not 4 weeks, it is not quite 6 weeks.
     
  9. scousespark

    scousespark

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    I don't have any issue understanding this term. Then again, I don't want to rewrite the regs and believe the members of JPEL/64 actually know a bit about electrical installation. Then again, I am just an electrician.
     
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  10. sparkwright

    sparkwright

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    A fused spur.

    A branch or spur that is fused.

    Seems logical enough to me.

    What else should it be called?
     
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