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Thread: Circuit breaker bussbar

  1. #1
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    Circuit breaker bussbar

    So I install a 3 tier DB and attempt to install a fork busbar (much better because it frees up the terminals for additional wires) on the top of the circuit breaker ... which is standard practise (in the top (line) and out the bottom (load) ) in SA ...everywhere else in the world in the bottom out the top ... but it doesnt work because there is no facilty at the top to fit the fork busbar ... only at the bottom.

    Check the diffrent manufacturers:

    CBI has the facilty at the top and the bottom ... the question ... are CBI breakers bi-directional?

    Onesto only has the busbar facilty at the bottom ... however they have a line (top) load (bottom) clearly labeled on the breaker ... it doesnt make sense.

    Hager have the facilty at the bottom ... their circuit breakers are bi- directional.

    ABB has the facilty at the top ... I know because it was the ABB breakers which got me started with the fork busbar.


    I have decided to start a new trend in SA ... all my DB's from today will be wired line in the bottom and load out the top.

    I am hop9ing that the main switch is also bidirectional and the earth leakage is in the top and out the bottom ... it will save the hassle of installing tails from the bottom of the main switch to the top of the earth lakage ... then from the bottom of the earth leakage to the top of the circuit breakers ( what a waste of time and wire)

    Wiring the DB in this manner will eliminate another issue of thermal heat generated when you cable tiethe loom nice and neatly around the DB.

    It just makes sense wiring the busbar at the bottom ... I think CBI are not bi directional and they dominated the market for too long ... it time to move forward and do it the right way ... in the bottom and out the top of the breakers.

    Din rail breakers are forward and so should be the fork busbar ... people have moved on form CBI ... it time do it right.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    Platinum Member Derlyn's Avatar
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    All circuit breakers for ac should be bi directional. The current changes direction 50 times each second.

    My 2 cents worth.

    That said, dunno if it's still taught.
    Circuit breaker in the top.
    Isolator in the bottom.

    The markings on many isolators dont agree with what I was taught.

    Peace out .. Derek

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    Full Member markthespark's Avatar
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    I have come across quite a few DBs wired with the load at top but only in dinrail and only in one particular suburb in Cape Town, Edgemead

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    Full Member markthespark's Avatar
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    But I do believe that the standard wiring in SA is load at the bottom and can be quite dangerous for inexperienced electricians if they come across the reverse!!!

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    Bi directional as in line (in) and load (out) ... it doesnt matter if you put the line (supply) in the top or bottom

    Onesto for example ... have markings on the front of the circuit breaker line at the top and load at the bottom ... which doesnt make sense because the fork bussbar only ftis in the load side of the circuit breaker ... there is no bussbar facility on the top.

    I am waitng for an email from Electromechanica which will confirm that I can as of today start wiring the simple way and not like we have been lead in the past by CBI.

    Apparently it states in the SANS regulations that it is legal to wiring in this manner provided it is labelled ... I havent found the regs yet ... but hope to have them soon.

    It just doesnt make sense wiring DB's the way we ave for past 50 years ... having to fit tails and looms around from the top to the bottom bottom to the top ... it would save wire ... time and look neater.

    I am going to check with the AIA and if I get the go ahead ... all my DB's will be wired the way they are designed to be wired ... The old CBI method is outdated and I havent used CBI since their pricing got ridiculous ... i buy 2 fully populated DB's for less than the price of 1 CBI earth leakage unit.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    Quote Originally Posted by markthespark View Post
    But I do believe that the standard wiring in SA is load at the bottom and can be quite dangerous for inexperienced electricians if they come across the reverse!!!
    The only reason it has been the "standard" is because CBI dominated the market since VIR wiring ...CBI no longer dominates the market ... and personally I dont agree with the way we wire DB's in SA and never have but just done it like that ... because it was said to be the norm ... times are changing and it is about time we saved wire and time.

    If someone can show me a regulation which prevents an electrician from connecting circuit breakers like this ... please post a copy.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    Hi
    I don't see the big advantage of wiring from the top or bottom and it would depend on the installation . If sockets are feed from the bottom of the DB and lights from the top.
    You would need to keep the DB the same and could not swop half way through the DB wiring .

    There is a regulation in ED2 ( pasted below) which you would need to take into consideration. - have still not got around to getting ED3

    I know of an Electrical contractor that was called for an emergency repair , Isolated the DB and without testing ( his fault and years of experience obviously made him assume to much) went in to tighten up a loose connection on the busbars.He is no longer around. The Bus bars should have had a Perspex cover over them with a warning live conductors. Somewhere along the line it went missing, he slipped on testing so a bit of a comedy of errors. Accidents happen quickly when you allow yourself to be rushed by the client.


    6.8.2.3 Circuit-breakers, disconnectors and switch-disconnectors shall not
    be mounted upside down. Horizontal mounting is allowed unless specifically
    prohibited by the manufacturer.
    Any deviation from the convention of connecting line to the top and load to
    the bottom of switchgear is not recommended. Reverse connection is
    allowed only if
    a) it is specifically allowed by the manufacturer,
    b) "load" and "line" are so marked that they are clearly visible during
    maintenance, and
    c) any contradictory marking is not visible after installation.

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    I find it strange that a circuit breaker manufacturer would design manufacture and supply circuit breakers with the bussbar connection on the load side ... then label the line at the top and load at the bottom ... it just doesnt make sense (but we are talking aboout MCE (still waiting for my credit )

    To add to the confusion ... offer an insulated busbar (fork type) in their new 2021-2022 catalog for their range of circuit breakers ... huh.

    IF you look in EM catalog on page B-9 you will see that they offer solution which connects to the bottom the the MCB ... I am sure someone can shed some light.

    Like they say on the EFixx channel ... designed to make an electricians life easier ... manufacturers are constantly looking at ways to make it easier for us ... but if we are set in old ways and led like sheep nothing will change.

    Anyone know who is responsible for the silly design and how it became the backward standard?
    Comments are based on opinion...not always facts....that's why people use an alias.

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    Quote Originally Posted by GCE View Post
    Hi
    I don't see the big advantage of wiring from the top or bottom and it would depend on the installation . If sockets are feed from the bottom of the DB and lights from the top.
    You would need to keep the DB the same and could not swop half way through the DB wiring .


    There is a regulation in ED2 ( pasted below) which you would need to take into consideration. - have still not got around to getting ED3

    I know of an Electrical contractor that was called for an emergency repair , Isolated the DB and without testing ( his fault and years of experience obviously made him assume to much) went in to tighten up a loose connection on the busbars.He is no longer around. The Bus bars should have had a Perspex cover over them with a warning live conductors. Somewhere along the line it went missing, he slipped on testing so a bit of a comedy of errors. Accidents happen quickly when you allow yourself to be rushed by the client.


    [/I]
    I would agree 100% ... if a DB is wired a certain way ... you would have to continue using the same method ... only brand new DB's or a full replacement will get the new system.

    I also havent got around to collecting ED3 and the only reason I have ed2 is because a friend immigranted to the UK and sold the book and all the notes to me at a reasonable price ... maybe we should club together and buy it online and share it amongst the regulars at a reduced rate ... one shelf in my office is dedicated to green and black books

    A long time ago (I had recently qualified as a sparky) ... I finished installing a 120mm x 4core ECC cable and was ready to terminal it into the main DB ... the more experienced electrician (site forman) told me the power was off ... I stepped on the the floor standing panel and grabbed hold of the red and blue bussbar to pull myself up ... the power was still on ... I was pulled into the panel as my muscles contracted which resulted in my face hitting the white phase bussbar ... a lot of bruising ... but I get to tell one of many horrific stories ... I have also been burnt from and explosion which resulted in a 1500 amp cicuit breaker tripping ... fortunately i regained my eye sight after about a half an hour ... a little burnt on the arms and face i walked away ... it was back when the ANC where terrorists bombing and killing civilians ... so the entire building was evacuated ... eeeish.

    I am sure most electricians have a scary story to tell.
    Comments are based on opinion...not always facts....that's why people use an alias.

  10. #10
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    SO MCE have confirmed ... it is an ooops ... it seems nobody thought about this issue.
    Comments are based on opinion...not always facts....that's why people use an alias.

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