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Thread: Bridge at bottom of two breakers

  1. #1
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    Bridge at bottom of two breakers

    At a recent inspection of an AC combiner box for an inverter system, I found the following on the AC side:
    2 SunSynk inverters and two AC combiner boxes.
    The first AC combiner box is for the Eskom in and the Inverter out and had an SPD, two 32 Amp double pole breakers, and a changeover switch in it.
    The Eskom in breakers has wire bridges at the bottom that go from Eskom in breaker to Eskom in breaker and then to the changeover switch.
    The second AC combiner box is for the Inverter in and Eskom out and had an SPD and two 32 Amp double pole breakers in it.
    The Inverter in breakers has wire bridges at the bottom that goes from Inverter in breaker to Inverter in breaker to the changeover switch.
    I'm pretty sure that having a bridge at the bottom of a breaker is not safe or legal.
    Also, the 10mm Neutral bridges that had been used on the breakers are more than two wires per breaker, also sure that this is not legal at all.

    My question now is what would be the best way to rewire it? My suggestion is as follows:
    Install two double pole breakers before the changeover switch, one for the combined Eskom load and the second for the combined Inverter load.
    Eskom in and the Inverter out loads can then be isolated independently and also together.
    The Neutrals must go from the breakers to a Neutral bar from where you can then have one wire to the changeover switch.
    VERY IMPORTANT, don't mix Neutrals.
    Have an Eskom out Neutral bar and an Inverter in neutral bar.
    Any other suggestions would be welcome.

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    Hello, would you be interested in drawing a diagram of the wiring in the 2 boxes? Just to get a clearer picture of what is going on there please.

    Sent from my R1PLUS_1 using Tapatalk

  3. #3
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    Sure, will do. The problem is not so much the red bridges but the black bridges and the ease to isolate the load

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    db ac.pdf
    I'm no engineer or artist, hope this help
    As I said my main concern is the use of two and three neutrals on one breaker, also you can't switch the load from both inverters off with one breaker

  5. #5
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    Quote Originally Posted by Thys LOW Elektries View Post
    db ac.pdf
    I'm no engineer or artist, hope this help
    As I said my main concern is the use of two and three neutrals on one breaker, also you can't switch the load from both inverters off with one breaker
    Above 4sqmm can only be 1 neutral in a terminal - Reg pasted below


    6.1.5 A maximum of three conductors may be connected to any one terminal
    provided that the terminal has the correct rating.
    NOTE Each neutral conductor exceeding 4 mm2 cross-sectional area should be
    terminated in separate terminals to facilitate disconnection of any one neutral conductor
    without disturbing the connection of any other neutral conductor.

    6.6.1.10 If a conductor of cross-sectional area exceeding 4 mm2 is used, it
    shall be so installed to allow any one neutral conductor to be disconnected
    without disturbing the connection of any other neutral conductor

  6. #6
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    Someone should send this reg to the DB suppliers



    Quote Originally Posted by GCE View Post
    Above 4sqmm can only be 1 neutral in a terminal - Reg pasted below


    6.1.5 A maximum of three conductors may be connected to any one terminal
    provided that the terminal has the correct rating.
    NOTE Each neutral conductor exceeding 4 mm2 cross-sectional area should be
    terminated in separate terminals to facilitate disconnection of any one neutral conductor
    without disturbing the connection of any other neutral conductor.

    6.6.1.10 If a conductor of cross-sectional area exceeding 4 mm2 is used, it
    shall be so installed to allow any one neutral conductor to be disconnected
    without disturbing the connection of any other neutral conductor
    Comments are my opinion, unless regulations are attached to support the comment. This is social media, not a court room.

  7. #7
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    I think 6.6.1.1 and 6.9.4 sums it up nicely If one has two or more supplies going out, one must be able to "interrupt the supply immediately" and not have to switch off three or four breakers to do it and hope the supply is switched off.
    Also, those small neutral bars are a waste of good time when you have large incoming supplies since anything bigger than 10mm2 doesn't fit in the neutral bar.
    I thought db's had to be made according to SANS regulations. I guess they never use cables thicker than 10mm2? Also, an 18-way db with 2 x 7-way neutrals never works.
    I guess starting to buy db's with no earth or neutral and installing neutrals and earths as needed is a good option then.

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