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Thread: General Electrical Questions - Construction

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    General Electrical Questions - Construction

    Good evening everyone. I have been reading through the forums and have had some questions answered, but there are still a few I'm wondering about.

    My first question is to do with twin-and-earth wiring. I see electricians wire light circuits with 1mm twin-and-earth. They say it's allowed as the whole installation is LED lighting and a typical circuit would barely draw more than 1 - 2 Amps. Seeing as a light circuit(s) can draw 10A allowed by the breaker and the 1mm T&E can carry 16A (if I'm not mistaking) I can understand their awnser but is it legal? Is it to do with the earth wire being too thin?

    Secondly, regarding stoves, some stoves come packaged with a short cabtyre lead connected to it (but no plug). Are electricians allowed to disconnect that cable at the connector block in the back and connect their cable coming straight out the wall into the oven? It cancels the need to make a joint, but does it effect the warranty of the stove?

    What is the difference between the ECB and ECA? What are the pro's and cons of being a member of the ECA?

    I have come across installations that have an earthing problem (no earth). It is also impossible to install an earth spike or earth mat as the building is surrounded by concrete, bricks and stone. One specific building was also a historical site and they did not allow for any conduit or wire to be installed on the outside. Some electricians say the only way then is to bridge the incoming neutral (above your mains) with the earth bar. I have also heard Electrical Engineers say that for extra safety, this can be done in any case on installations. Is this valid?

    Are DB's required to have a mains breaker if it has an earth leakage with no overload protection? Keep in mind, this question only pertains to installations with prepaid meters which has overload protection. Again, I heard that if it has a prepaid, it doesn't need a MCB. Is this correct?

    Is it still a requirement to install a MCB in the draw box on the outside of the house? (it's usually the CBI 60A 5kA mains). I spoke to an electrician from the municipality the other day, and they say they don't want them installed because it makes it easier for people to bypass their meters.

    TIA

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    Hello Brother

    Many long questions, so my contribution is gonna be long as well.

    Firstly
    1mm cable (Max current carrying capacity is 11 Amps) can be used but the breaker cannot have a trip rating of more than 10 Amps and the maximum length may not exceed 26 meters. See table 6.2(a) and E.2(a) SANS 10142

    Secondly
    Appliances meant to be plugged into a socket outlet, legally, must be sold with a plug attached.
    Appliances need to be connected according to manufacturers specifications. If the appliance is intended to be plugged into a socket outlet, then that's how it should be done.
    It's in the manufacturer's interest to find any reason to invalidate the warranty.

    Thirdly
    I'll give this one a miss.

    Fourthly
    We have whole suburbs where no separate earth is supplied by the supplier. ( 2 core overhead supply )
    The consumer earth is bridged with the neutral in the prepaid meter before the main breaker.
    So to answer your question "is this valid"? ...... Yes.

    Edited 30/6/2020 17h38. Just had to add, our Municipality does not allow bridging of the neutral and earth in the DB. It must be done on the supply before it enters the DB.

    Fifthly
    This depends on where the installation is and what the local by laws say. In East London, the DB needs to have over current protection irrespective of whether the meter is prepaid or not. Have spoken to an electrician in Durban and apparently it is not a requirement there. Maybe someone from Durban can confirm if this is indeed the case.

    Lastly
    On new domestic installations, the cable is drawn from the stubby on the pavement directly to 4x4 box next to the DB. This is for the prepaid meter. Draw boxes on the outside of houses were used in days gone by to house the Municipal credit meter. When the municipality here in East London removes a credit meter from these boxes in order to install a prepaid meter in the house, they also remove the circuit breaker and crimp the live supply. I would think that this is to prevent the user from turning off the municipal supply to the meter to minimize the chances of meter monkey business occurring.

    Hopefully some of the other toppies can expand on my contribution.

    Cheers and peace out ... Derek
    Last edited by Derlyn; 30-Jun-20 at 05:39 PM.

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    Hi
    Think Derek has pretty much answered your questions beside ECA , ECB

    ECA is a registered employers organization , is party to the National Electrical Bargaining council (NBCEI) , and actively involved in all spheres of the industry that have an effect on us.
    ECA provides assistance and has representation in Technical, Contractual , Labour and Training.
    ECB tends to be more involved in Technical only.

    Have a look at the service offerings on both websites and do the comparisons- Speak to your local ECA office and contractors that belong to ECA in your area.

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    ECA or ECB ... one thing to add ... organisaion to protect the "electrical constractor" ... which should in turn create a safer environment for the customer ... I actuall work in the industry ( i dont sit in an office or spend the day looking for new golf clubs or bicycle parts and send teams to site) .. i see what actually happens on site and the challenges we have to deal with when "teams" are dropped off or sent to site.

    I resigned from the ECA around 20 years ago ... i do miss the free snacks at the meetings ... all bitching about rates ... and the bad workmanship of other electrical contrators ... etc etc ... but that is about it ... i can say that the 10 years i was a member ... there was no real benefit to my small bussiness ... as a big contractor with lots of staff ... it may be wiser to have the support.

    I must say i have been rather impressed with the ECB information shared during the lockdown ... and i am not even a member ... they send me emails informing me about all sorts of industry related topic.
    Comments are based on opinion...not always facts....that's why people use an alias.

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