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Caravan electrical hook up?

D4G
I've been asked to install a supply to a hook up for a caravan in a garden.

I see that the connection of a PME earthing facility to any metal work is prohibited, is there anything else I may have overlooked?


Thanks in advance :)
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    RCD supply to the socket, earth electrode, current ratings, voltage drop, loads of things - you may have remembered them or not, from your post it is hard to tell, more data on your design please.


    Is the house supply TNC-s? If it is TT or TNS, you do not need to island the caravan and can just extend the house wiring as it is.


    If house is TNC-s and you are creating a TT island, then assuming power is going outside in SWA, then earth the armour at the house end, so the PME still protects the cable against damage, but at the caravan end, use a large stuffing gland and isolate the armour,  taking an earth from a local electrode into the caravan.

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    Hi Mike, sorry for the lack of information, my main concern was with anything caravan side of the hook up.

    The hook up unit will be supplied with SWA from the house DB, the house supply appears TNCS.

    This is what I was after thanks:

    "If house is TNC-s and you are creating a TT island, then assuming power is going outside in SWA, then earth the armour at the house end, so the PME still protects the cable against damage, but at the caravan end, use a large stuffing gland and isolate the armour,  taking an earth from a local electrode into the caravan."


    Dan
  • 0

    If it is TT or TNS, you do not need to island the caravan and can just extend the house wiring as it is.



    Although most UK DNOs advise that apparently TN-S supplies should be treated as if they were PME - since they often don't maintain neutral-earth separation within their network these days. The DNOs may occasionally guarantee a TN-S supply won't be PMEd but it's rare and usually reserved for things like big caravan sites or marinas - not something you're likely to find for a normal domestic supply.


       - Andy.
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    Is it a touring van that will taken out of the garden to go on trips away or a permanently installed static van?


     Andy Betteridge
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    Also note that caravan supplies require individual 30mA RCD protection that opens all live poles (including N) - so no relying on a SP RCBO or shared RCCB back at the CU.


    The sockets are now required to be interlocked - beware of the older style hookup boxes or simple BS EN 60309 sockets.


    For underground cables BS 7671 recommends a minimum depth of 600mm in the pitch area unless provided with additional mechanical protection and 6m height for overheads in areas subject to vehicle movement.


    (plus several other pages in section 708)


       - Andy,
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    Sparkingchip:

    Is it a touring van that will taken out of the garden to go on trips away or a permanently installed static van?


     Andy Betteridge 




    It's a touring caravan which may be taken away on occasions.

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    Ah well, if it is unoccupied, and gets driven off to be used then the situation is not as severe as a formal caravan park for visitors - I'd  be less worried about tent pegs and so on, even assuming the SWA runs under grass and not either a paved area or alternativley is clearly visible. Actually, just for occasional charging and so on, I'd not be that phased by the PME either, it is similar to a lot of car chargers. (ignoring legislation, there must be plenty of private vans that are essentially on an extension lead from the house with no thought at all to earthing)


    However to do it properly, an MCB and an RCD or a dual pole RCBO, and suitable socket, and as noted the islanding of the earthing. Have a think about the routes of drains and gas pipes etc before hammering a rod in willy nilly, or the cost goes up rather a lot.

  • 0
    Thanks Mike

    mapj1:

    Ah well, if it is unoccupied, and gets driven off to be used then the situation is not as severe as a formal caravan park for visitors - I'd  be less worried about tent pegs and so on, even assuming the SWA runs under grass and not either a paved area or alternativley is clearly visible. Actually, just for occasional charging and so on, I'd not be that phased by the PME either, it is similar to a lot of car chargers. (ignoring legislation, there must be plenty of private vans that are essentially on an extension lead from the house with no thought at all to earthing)




    It's more for the availability to put up friends on occasions who may want to boil a kettle or have hot water, with the possibility of towing away to be used for holiday purposes.... 




    However to do it properly, an MCB and an RCD or a dual pole RCBO, and suitable socket, and as noted the islanding of the earthing. Have a think about the routes of drains and gas pipes etc before hammering a rod in willy nilly, or the cost goes up rather a lot.

     




    Haha, don't worry I'm not a 'willy nilly' type of person!

     

  • 0
    IET Guidance Note 7 recommends a separation distance of 10 m below ground between the TT earth electrode of a caravan, and a PME system used to supply it.


    However, that may be problematic in many domestic premises, because of a "return of touch potential" issue - this is covered in Annex H of the 4th Edition of the IET CoP for EV Charging Equipment Installations (example in Figure H.4).



    "Just TT it" isn't always a good solution.
  • 0
    708 does not apply by virtue of their being only one caravan. That is not to say that guidance therein should be set aside. However, any risk from a connection to a TNCS terminal for a single caravan for occasional use in someone’s back garden is likely to be close to zero. Had your clients simply asked you to provide a weather proof socket in their back garden for general use, then other than the additional protection and depth of cable, no special precautions would be necessary. If they wanted to use it to plug in their touring caravan that would be their prerogative. 

    you will note that not even the ultra-cautious bods at electrical Safety First have raised any concerns about hook ups to the thousands of vans sitting in driveways across the U.K. 


    edit to correct section number

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