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How to supply a 20A Distribution cct?

Farmboy
Sorry if this is too simplistic a question but I'm wondering what you think, given I've had conflicting views from a trade assoc tech dept and Hager tech dept.


A 65m, SP+N, 20A (estimated, but could be subject to some increase) distribution cct, fed from within a commercial setting (an osteopathy/acupuncture service provided in a converted ground floor flat), is to supply a shed/summerhouse with a couple of sockets (for a kettle and TV) and a couple of LED bulkheads (via cb's in the shed CU), sited at the end of the garden. How would you supply the distr. cct at the meter position?

- From a henley block in the existing tails:

              - Its own modular enclosure containing DIN rail mounted main switch and 20A fuse carrier.

              - A rotary handled 20A fused switch disconnector.

- From a 20A cb in the existing CU.


From the trade assoc., one said from the CU, another said it's got to have its own main sw, another said no problem with the modular encl and fuse carrier. While Hager said its got to be the rotary type, not the fuse carrier.


F
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    mapj1:




    will need 10.0 or 16.0mm2 for Volt drop limitation at 20 Amps over 65 metres.






    No it won't - 16mmsq is more than you need to supply a small house or flat !!

    It's not a lighting-only circuit, so the larger volt drop figure applies. You may need 6mmsq, not more.

    ..........................................................................................................................................................................................................................................6.0mm2 as an absolute minimum, 10.0mm2 preferably.

    Well, a house does not normally have a 65 metre run for its internal main supply cable.


    The outbuilding will have lighting so the 3 percent max. Volt drop will apply in my opinion. Also if 10.0mm2 or 16mm2 is installed for a 65 metre run rated at 20 Amps. it limits Voltage drop and it allows for future extra loads.


    With a 20 Amp load and a 65 metre run  using 6.0mm2 cable I calculate that the Volt drop will be just short of 10 Volts. Doesn't that create a loss of just under 200 Watts?


    Z.


     



     




     

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  • 0

    mapj1:




    will need 10.0 or 16.0mm2 for Volt drop limitation at 20 Amps over 65 metres.






    No it won't - 16mmsq is more than you need to supply a small house or flat !!

    It's not a lighting-only circuit, so the larger volt drop figure applies. You may need 6mmsq, not more.

    ..........................................................................................................................................................................................................................................6.0mm2 as an absolute minimum, 10.0mm2 preferably.

    Well, a house does not normally have a 65 metre run for its internal main supply cable.


    The outbuilding will have lighting so the 3 percent max. Volt drop will apply in my opinion. Also if 10.0mm2 or 16mm2 is installed for a 65 metre run rated at 20 Amps. it limits Voltage drop and it allows for future extra loads.


    With a 20 Amp load and a 65 metre run  using 6.0mm2 cable I calculate that the Volt drop will be just short of 10 Volts. Doesn't that create a loss of just under 200 Watts?


    Z.


     



     




     

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