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ac supply

Discussion in 'Solar PV Forum' started by gordysolar, Feb 17, 2012.

Discuss ac supply in the Solar PV Forum area at ElectrciansForums.co.uk.

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  1. gordysolar
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    gordysolar Guest

    Is it best to connect ac supply from origin or is it ok to connect to a sub board in a garage? if not get cable back to house board where meter is?
     
    Last edited by a moderator: Feb 17, 2012
  2. grandfortune
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    grandfortune Solar Guru

    Location:
    Midlands
    Cut into the main tails and fit new 2 way DB
     
  3. burra101
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    burra101 Guest

    yeah henley block and 10mm tails into a 2 way db and a 16 amp mcb i always put
     
  4. VMan
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    VMan Guest

    I dont see why you couldn't use a sub board, as long a the VD & cable supply ok
     
  5. GaryM
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    GaryM Guest

    No problem at all but supplied from source via a henley block would allow the customer to measure generated current and usage current independently of each other, if that's what they would prefer to do.

    Mine is supplied from a spare way in my main consumer unit as I'm fine with the way I monitor energy.
     
  6. fiardor
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    fiardor Regular EF Member


    And if i am reading the original post correctly he is asking if he cant get a cable back to the origin so a henley block/tails/CCU scenario isnt a viable option.

    And always a 16a mcb? No RCD/rcbo protection ever? Surely not always mcb's unless every instal is the same?

    You could possibly use the existing db in the garage if-

    1. The supply cable is of sufficient size to allow for 1% volt drop.
    2. Depending on the inverter you are installing, the db will almost certainly have rcd protection at either origin or at db so it could be problematic to instal a 16a mcb/rcbo to this db.
    3. Err
    4. :D
     
    Last edited: Feb 17, 2012
  7. infinity
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    infinity Electrician's Arms

    Location:
    fareham
    Shouldnt the tails be a minimum of 25mm according to the new ammendment?
     
  8. GaryM
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    GaryM Guest

    What would you calculate the potential loading be that the tails would have to carry?
     
  9. yellowvanman
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    yellowvanman Electrician's Arms

    Location:
    Dorset
    Not saying your wrong but if the ammendment specifies this can you tell me the reg number.
     
  10. GaryM
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    GaryM Guest

    There's more chance of 25mm tails being mentioned in the OSG than BS7671.
     
  11. infinity
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    infinity Electrician's Arms

    Location:
    fareham
    Give me a min just dusted it off i know ive seen it somewhere...
     
  12. infinity
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    infinity Electrician's Arms

    Location:
    fareham
    OSG 2.2.3
    Taken from the OSG.... Page 17

    2.2.3 Meter Tails
    These are part of the consumers installation. They should be insulated and sheathed or insulated and enclosed in conduit or trunking. They are provided by the installer.

    Polarity should be indicated by the colour of the insulation and the minimum cable size should be 25mm. The distributer may specify the maximum length and the minimum cross sectional area.

    Where the meter tails are protected against fault current by the distributers cut out the method of installation, maximum length and minimum cross sectional area must comply with the requirments of the distributer.


    knew i read it somewhere
     
  13. GaryM
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    GaryM Guest

    That's the OSG, a guide only for people who can't engineer solutions for themselves. No problem at all with 10mm tails supplying a one way CU with a 16A MCB for a PV system.
     
  14. moggy1968
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    moggy1968 Electrician's Arms

    Not according to my assessor! the maximum current under useage is 16 amps so there is no potential for overload of the 16mm tails. In the event of a fault (i.e. direct short) which is going to fail first, the 1mm or so thick fuse wire or the 16mm tails. IT'll be the fuse every time so 16mm tails are fine on a garage sub board (or even on a domestic board if your maximum demand is less than 80ish amps that I can't recall off the top of my head)
    And of course 16mm tails are a whole lot easier to work with!!
    Even if demand is above the limit you can still use 16mm tails if you fit a main breaker at the point of origin of a suitable size. This was the scenario I discussed with my assessor where it was impossible to change the meter tails on a board change without doing substantial damage to the property.
     
    Last edited: Feb 17, 2012
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