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Thread: Wire size

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    Wire size

    Hi All
    In a DB I have a 60 amp main switch. Would 10mm single core house wire be large enough for the outgoing of the 60 amp main switch.
    Summation of loads is higher than 60 amps.
    I am not sure where DB wires ratings fit in on the cable rating charts.[clipped direct??]
    Maby someone could help.
    Or am I missing the ball totally.
    I know 16mm cable is OK.
    In this same DB I have a situation where the supply cable is 16mm to the prepaid meter. From the prepaid meter the installer installed a 10 mm single core wire to the main 60 amp isolator/circuit breaker. The question would be is this 10mm from the prepaid meter to the main isolator fine as per the SANS charts. Where do DB wires fit in on the SANS charts.


    Thanks



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    Morning

    The size of you cable is determined by the size of your breaker.

    So for 60 amp 10mm is in order.

    As for the loads being greater if this is the case your breaker will trip.

    I find that DB boards with 60 amp mains wired with 16mm becomes a challenge in terms of space.

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    we only use 16mm for a 60 amp breaker

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    Thank you

    Can anyone tell me the current rating of 10mm house wire single core in a DB. The ratings on sans table range from 52 A 54 A 65A. Depending on how it is installed. The cable manufacturer rate it at 61 amps.
    These values are more or less out of my memory.
    Is there possibly another way of looking at this.
    The existing installation is fed with a 16mm cable up to the prepaid meter then from the meter it is 10mm.The main breaker is 60 amps.
    Is the 10mm house wire suitable. Do I change all to 16mm.

    Trying to get it right.




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    A quick fix ...change the breaker to a 50 amp...that way you are covered... or if the customer is not whining about cost. .. just put a 16 mm cable and be done...at least you know it is right.

    What i see often is the circuit breaker in the meter being upgraded to an 80 amp ...the supply cable from the council use to be a 25 mm ...but the supply cable from the meter to the main DB was only 16 mm ...i am yet to hear of a building burning down from this incorrect wiring.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    Gtfast (28-Feb-20)

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    Quote Originally Posted by Gtfast View Post
    Thank you

    Can anyone tell me the current rating of 10mm house wire single core in a DB. The ratings on sans table range from 52 A 54 A 65A. Depending on how it is installed. The cable manufacturer rate it at 61 amps.
    These values are more or less out of my memory.
    Is there possibly another way of looking at this.
    The existing installation is fed with a 16mm cable up to the prepaid meter then from the meter it is 10mm.The main breaker is 60 amps.
    Is the 10mm house wire suitable. Do I change all to 16mm.

    Trying to get it right.




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    Your answer is found in Table D.2(a) on page 309 of SANS 10142-1.

    For a 60A breaker, 10mm is fine up to a maximum length of 43 meters.

    Cheers and peace out ... Derek

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    Gtfast (28-Feb-20)

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    Thanks for the input guys.
    Appreciate it.

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