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Thread: Can an Earth leakage be used as a main switch ?

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    Can an Earth leakage be used as a main switch ?

    Hi guys, I hope you are well.

    I would like to find out if the following would be considered compliant.

    A CoC was recently issued on a property where there is no separate main circuit breaker on the DB board, the earth leakage is being used as both the main switch & earth leakage.

    There is only one DB board on the property which is fed directly from the Eskom box on the side of the road, there is no inline circuit breaker between the Eskom box and DB board. Based on this there is no way to isolate the DB as the Eskom box is locked.

    Would this be considered compliant ?

    I have attached a photo of the DB board as reference.

    Thanks in advance for any assistance.

    Click image for larger version. 

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    Silver Member Derlyn's Avatar
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    Not legal.

    Each conductor that forms part of the installation must be protected by an over current protective device. An earth leakage is not an overcurrent protective device.

    6.7.1.3. Eskoms protective device can serve the purpose but only if eskom agrees and if the user has access to it which you have stated is not the case.

    Here in my valley we use a double pole circuit breaker for the main switch, so that should there be a serious short somewhere, it will trip on the db and not in the supplier's kiosk.

    I would not have issued a coc for that db.

    Also very impractical in that one cannot remove the lights circuit or stove circuit from the earth leakage if you so desire.

    Peace out .. Derek
    Last edited by Derlyn; 19-Sep-21 at 07:01 PM.

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    Site Caretaker Dave A's Avatar
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    And there I was thinking the question was whether the earth leakage unit can act as the main switch (disconnector). Which as it disconnects both the live and neutral in this single phase installation at the point of supply, the answer is obviously YES, the earth leakage unit can also act as the main switch disconnector.

    It is not required to have a separate main switch disconnector.
    The issue of overcurrent protection is another matter...

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    Silver Member Derlyn's Avatar
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    @Dave

    Of course you are correct, an earth leakage may be used as an isolator, but only under certain conditions.

    Had the db in the photo been a sub db fed from the main db through a suitable circuit breaker then it would be acceptable and I would have passed it.

    In this case it is the main db and neither the earth leakage nor the jumpers feeding the circuits has overcurrent protection. The manufacturer specs state that the earth leakage must have seperate overload protection, which it hasn't got, so this particular db is not compliant.

    Steven asked whether the db is compliant.

    I say no.

    Peace out .. Derek.

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    As per the picture ... I am impressed to see someone actually fit a label ... "fed from ....." not often you see that.

    In our part of the country ... it is legal to use an earth leakage unit as a main switch ... so long as it is correctly rated ... IE: if the circuit breaker in the meter box feeding the earth leakage is 60 amps or less and the earth leakage is rated to 60 amp ... it would be regarded as legal ... it just becomes a nuisance tripping issue.

    By the way ... there should be be a circuit breaker in the meter box to protect the cable from the meter to the main DB.

    Just looking at the picture ... it looks like someone did actually go to the site and carry out a test ...fit DB blanks and the correct labeling

    Can an earth leakage be used as a main switch ... I agree with Dave ... in our part of the country .. yes.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    Silver Member Derlyn's Avatar
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    Quote Originally Posted by ians View Post
    As per the picture ... I am impressed to see someone actually fit a label ... "fed from ....." not often you see that.

    In our part of the country ... it is legal to use an earth leakage unit as a main switch ... so long as it is correctly rated ... IE: if the circuit breaker in the meter box feeding the earth leakage is 60 amps or less and the earth leakage is rated to 60 amp ... it would be regarded as legal ... it just becomes a nuisance tripping issue.

    By the way ... there should be be a circuit breaker in the meter box to protect the cable from the meter to the main DB.

    Just looking at the picture ... it looks like someone did actually go to the site and carry out a test ...fit DB blanks and the correct labeling

    Can an earth leakage be used as a main switch ... I agree with Dave ... in our part of the country .. yes.
    The chances that the circuit breaker in the meter box feeding the db is 60 Amps or less is probably about 2%.
    I have never seen smaller than 70 or 80 Amps. Anyway that's here in East London.

    As far as I'm aware, there is only one make of earth leakage that offers both leakage current and overcurrent protection that is readily available and it's only in Samite and by CBI. They are not cheap.
    The rest basically all require seperate overcurrent protection.

    When I come across a main db with only an isolator as the main, I always install a 60Amp main breaker as well so that the earth leakage relay is protected. A single pole breaker in the main live is enough.

    Peace out ... Derek.

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    Derek I agree with you regards the 80 amp circuit breaker ... I see it a lot of meter boxes around here with 80 amp circuit breakers ... but very seldom see a 80 amp main switch or 80 earth leakage unit used as the main switch ... the question .... can one use an earth leakage as a main switch ... I still say yes.

    however ... I would agree that a 60 amp breaker before the main switch or earth leakage would be good practice in many cases ... what I think has happened as I have seen in many cases ... the outbuilding is turned into a granny flat ... the power to the granny flat has a 6/10 mm cable with a 40 or 50 amp breaker ... the granny flat has a stove ... geyser and the works ... council breaker breaker trips in the meter box ... the council electrician visits the site with a duspol tester ... removes the breaker and fits an 80 amp to prevent it tripping again.

    While on the subject of 60 and 80 amp circuit breakers in the meter box ... I have seen in many cases the fuse on the pole to protect the cable from the pole to the meter box is an 80 amp with a 25 mm concentric cable ... but the cable from the meter box to the main DB is only 16 mm house wire or armoured cable ... which when installed must have had a 60 amp breaker protecting the cable ... but since been upgraded to 80 amp and the cable has not been upgraded to 25mm.

    Lets not even go down that road ... that is a whole thread on its own.

    Back to the question asked ... it would need to go back to the person who started the thread ... do you have a 16 mm wire with a 60 amp circuit breaker in the meter box ... if your answer is ... yes ... then the answer would be yes it is compliant ... if not and you have an 80 amp circuit breaker in the meter box ... I would agree with Derek and say no it is not compliant ... and and suggest a 60 amp circuit breaker is installed before the earth leakage.

    We as electricians cannot tamper with the circuit breaker in the meter box ... I would suggest a 60 amp D curve or curve 1 breaker be used rather than a standard 60 amp.

    Personally I dont agree with having the entire house on earth leakage ... it becomes a hassle fiddling in the dark trying to get to the earth leakage to reset.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    Something I would investigate the circuit labelled plugs /gate ... that looks interesting ... is there a weather proof plug at the gate fed from a socket in the building ... or is the gate fed directly from the DB to a weather proof socket or is the gate fed from the plug circuit directly to the motor with lights on the pillar ... this kind of thing tends to get interesting.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    Quote Originally Posted by Derlyn View Post
    The chances that the circuit breaker in the meter box feeding the db is 60 Amps or less is probably about 2%.

    As far as I'm aware, there is only one make of earth leakage that offers both leakage current and overcurrent protection that is readily available and it's only in Samite and by CBI. They are not cheap.
    The rest basically all require seperate overcurrent protection.


    Peace out ... Derek.
    There are other makes that have Overcurrent protection , or combined units as the reg's refer to

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    With regards to an ELU being legal as a main switch -
    It is not a str forward answer and there are numerous factors that need to be taken into account.
    The same factors need to be taken into account if you use a standard Isolator as a main switch.

    A ELU isolator type and Isolator that numerous contractors use in a DB as main switch , does not have a KA rating unless that isolator is protected by a suitable tested solution .

    A 60 Amp ABB CB protecting a 60 Amp CBI Isolator would not be a tested solution and you could therefore not sign a COC off saying that the CBI isolator is suitable rated KA .

    The same way that a 250 Amp ABB CB protecting a 350AMP ABB Isolator is not a tested solution and you cannot sign it off on a COC - Sounds crazy, but that is how it is .

    Before signing off ensure that the CB before the isolator is a tested solution otherwise you will not know what fault level the isolator is capable of handling .

    An isolator cannot trip , and therefore has no overcurrent rating , so how can it have a KA rating

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