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  1. rubicon
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    rubicon EF Member

    Hi guys, I'm about 4000 words deep into my first write up..

    I've now got onto the fault finding section, I've go to answer the following..

    Perform tests to find the following faults:
    Loss of supply
    Overload
    Short circuit and earth fault
    Transient voltage
    Loss of phase, line
    Incorrect phase rotation -DONE
    High resistance joints -DONE
    Componant, accessory or equipment faults -DONE

    So basically I've got to write a few lines/paragraph about each fault. But I'm finding it tough as I don't really come across faults, especially not complex ones like transient voltage!!!

    The most I've actually come across in mt 2 years so far is a few faulty accessories and loose connections (loose screw at terminal)

    So those are what I've covered so far.. But struggling to think of examples for the rest..? As say loss of supply is so broad/could have many ways of showing itself/being tested for.

    If anyone has any tips I'd be hugely grateful!!!!! (Obviously not asking for somoene to write it for me.. but any kind of example would be great)
     
  2. Wilko
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    Wilko Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Loss of supply suspected - two pole voltage tester used to confirm at DB as extension of the initial safe isolation procedure, perhaps ?
     
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  3. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    following on..

    overload. MCB/fuse tripping/ cable overheating.

    anyone for #3?
     
  4. rubicon
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    rubicon EF Member

    Thanks Wilko, good example.. Do you think that counts as a fault? My write-up revolves around a new build apartment block so i could perhaps state that 'an apartment was experiencing an apparent loss of supply from the switchroom below so I used a two pole voltage tester at the CU to confirm this?'

    Thanks telectrix I will build on one of those for the overload section. Shouldn't be too hard
     
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  5. rubicon
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    rubicon EF Member

    With the overload.. Which test would actually diagnose that?

    I understand the fault but lost as to how it'd be 'diagnosed' in the proper way
     
  6. Wilko
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    Wilko Electrician's Arms

    Location:
    Berkshire
    Business Name:
    Wilko Electrics
    Overload may the cause of reported mcb tripping during use. Example might be a pump connected to a B type mcb is reported to work ok, but sometimes trips mcb. This may be caused by the starting current of the motor, for example.
     
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  7. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
    Business Name:
    Telectrix
    overload is easily checked using a clamp meter. if this equation is not satisfied, then you have a problem...... Ib<In<Iz.
     
  8. westward10
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    westward10 In echoed steps I walk across an empty dream. Electrician's Arms

    Location:
    Northamptonshire
    The key to the answers it that they are asking "what tests" you need to carry out.
    1. Loss of supply, voltage indicator across all points of supply.
    2. Overload, clamp meter.
    3. Short circuit/earth fault, insulation resistance test.
    4. Transient voltage, much harder I think you need some monitoring /analysing equipment?
     
  9. rubicon
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    rubicon EF Member

    Thanks guys all really helpful. How's this for example..

    Overload - In the car park, one of the breakers on a communal Distribution Board was tripping intermittently. This was a feed which supplied a boiler room (heats water for the apartments) We also noticed upon visual inspection that a cable was very warm upon touching, signalling it was being overloaded. I confirmed this by using a clamp-on ammeter on the SWA suppling this room to see what current was being pulled by this equipment.
     
  10. Richard Burns
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    Richard Burns Trusted Advisor

    Location:
    Cambridgeshire
    Business Name:
    Richard Burns
    I did write a reply to a similar question some time ago and this was repeated in this post. However I would work more toward getting an answer in place before reading it so that you can learn more with your own understanding.

    The scenario you pose above where a distribution circuit to a boiler room is tripping may mean that there is insufficient discrimination for the circuits in the boiler room, because the installation should be designed so that an individual circuit should trip rather than a distribution circuit. Therefore confining your answer to a final circuit might be a more comfortable scenario, and easier to fault find!:)
    Other than that it it a good answer, though it would be noted that during the (not necessarily just visual) inspection of the circuit it was noted that the outer sheath of the supplying cable was hot (remember an overload of the circuit breaker should not mean an overload of the cable as the circuit breaker should be designed to prevent the cable ever exceeding 70°C internally or about 50°C externally for SWA (or possibly 90°C in a few specialised cases)).
    Using safe isolation and working procedures access was arranged to the line conductor of the SWA cable so that a measurement of current drawn could be taken using a clamp meter once the circuit was re-energised. The current was found to be in excess of the rating of the supplying circuit breaker for significant periods of time. Further testing of individual accessories resulted in the fault being traced to the ____ and the repair of this item resolved the fault as confirmed by further testing.

    Something like that anyway.
     
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  11. rubicon
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    rubicon EF Member

    Thanks for the answer above thats very helpful! I'll elaborate a little when I go back to edit that section. I'm now on the 'environmental' section which is a bit tricky as it says..

    3.1 Provide information on the following:

    Solar photovoltaic

    Wind energy

    Micro hydro

    Heat pumps

    Grey water recycling

    Rain water harvesting

    Biomass heating

    Solar thermal hot water heating

    Combined heat and power including micro CHP


    ..Now I know how some of these work as I've done them whilst at college etc but things like grey water recycling?? I'm a bit lost.. Anyone know where I could find out about these and then I can construct my own little paragraphs about them?
     
  12. Richard Burns
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    Richard Burns Trusted Advisor

    Location:
    Cambridgeshire
    Business Name:
    Richard Burns
    Solar photo voltaic you must have heard of and seen, similarly with wind energy although possibly not on a small scale, micro hydro is less common but can be done locally, heat pumps are generally larger scale but from office block operations is possible, grey water recycling is using washing water and other once used water for low grade water supply such as watering plants, Rain water harvesting is like grey water recycling but with rain, biomass heating is using growable material for fuel, solar thermal is also fairly common for peoples hot water tanks, slow but workable, CHP is biomass heating with power generation.
    Wikipedia should have details on all these and if you search for green energy and home power and heat then a plethora of websites should present.
     
  13. Simonslimline
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    Simonslimline Electrician's Arms

    Location:
    South West, Bath
    Is this assignment work? Or are you doing a write up for job 1 of the actual NVQ evidence?





     
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