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    Unusual RCCB connection

    I have a 4 pole 415 volt RCCB and a 2 phase 415 volt welding machine. How to connect this welding machine with 4 pole RCCB so that my purpose of electrical safety is achieved and,RCCB also work at its full potential?
    [COLOR="#008000"]Insearch of clear concepts[/COLOR]

    #2
    Do you have a picture of the RCCB?

    Connect as you would with a 4 wire application, but simply do not involve the pole not hooked up to the circuitry/test resistor. Run the neutral to the RCCB source side, but don't use it on the load side.

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      #3
      4 pole 415 VAC RCCB
      Attached Files
      [COLOR="#008000"]Insearch of clear concepts[/COLOR]

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        #4
        Originally posted by mbrooke View Post
        Do you have a picture of the RCCB?

        Connect as you would with a 4 wire application, but simply do not involve the pole not hooked up to the circuitry/test resistor. Run the neutral to the RCCB source side, but don't use it on the load side.
        I have posted image of RCCB
        [COLOR="#008000"]Insearch of clear concepts[/COLOR]

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          #5
          This will help based on a generic RCCB, but ultimately you must confirm the wiring diagram on your own RCCB.
          Attached Files

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            #6
            Originally posted by Abhi View Post
            4 pole 415 VAC RCCB
            In that case ignore the first picture, and try this:
            Attached Files

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              #7
              Originally posted by mbrooke View Post

              In that case ignore the first picture, and try this:
              I think it will work as a mcb and not as a rccb. For behaving it as rccb, neutral must be involved
              [COLOR="#008000"]Insearch of clear concepts[/COLOR]

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                #8
                Originally posted by Abhi View Post

                I think it will work as a mcb and not as a rccb. For behaving it as rccb, neutral must be involved
                I do not think your RCCB pictured has short circuit and overload protection. Just differential protection.

                Yes- in order for the test resistor to work neutral must be provided and involved with the RCCB.

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                  #9
                  Originally posted by Abhi View Post

                  I think it will work as a mcb and not as a rccb. For behaving it as rccb, neutral must be involved
                  It is in both of mbrooke’s diagrams in that the neutral is being sensed by the summation CT. Whether or not your load actually connects to that neutral is irrelevant to the operation of the RCCB. Current out to the load on either pole must equal current returning on the other. No neutral current flowing just means that the neutral current, or rather lack of it, is irrelevant to the residual equation.
                  __________________________________________________ ____________________________
                  Many people are shocked when they discover I am not a good electrician...

                  I'm in California, ergo I am still stuck on the 2014 NEC... We'll get around to the 2017 code in around 2021.

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                    #10
                    Originally posted by Jraef View Post

                    It is in both of mbrooke’s diagrams in that the neutral is being sensed by the summation CT. Whether or not your load actually connects to that neutral is irrelevant to the operation of the RCCB. Current out to the load on either pole must equal current returning on the other. No neutral current flowing just means that the neutral current, or rather lack of it, is irrelevant to the residual equation.
                    Yes, my load is a double phase welding machine which requires only two phase wire of 415 VAC 3 phase. There is no provision for neutral connection.

                    If I connect only two phase load to any two of the three poles of RCCB then it must work, as you told.

                    And plz explain about testing part of 4 pole RCCB
                    [COLOR="#008000"]Insearch of clear concepts[/COLOR]

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                      #11
                      I did not connected any load to RCCB and supplied only 3 phase. And neutral was also not connected. I don't understand, how test circuit worked. Plz help

                      I have attached some pics for reference

                      Sent from my Redmi 3S using Tapatalk

                      [COLOR="#008000"]Insearch of clear concepts[/COLOR]

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                        #12
                        Originally posted by Abhi View Post
                        I did not connected any load to RCCB and supplied only 3 phase. And neutral was also not connected. I don't understand, how test circuit worked. Plz help

                        I have attached some pics for reference

                        Sent from my Redmi 3S using Tapatalk
                        Your RCCB will function as a summation of all the current passing thru it-->all should sum up vectorially to zero. Any current that will not be sensed by the breaker will be treated as "leakage" and it's up to the breakers sensitivity to either trip or not(I sensitivity >30ma)! Not wiring the neutral (if load does not need a neutral) means there will be no current thru it even if you wired it in. Test button simply simulates a leak on the trip circuitry of your breaker by allowing a small amount of current to pass outside of you CB's summation CTS, a resistor of a value just enough to imitate a leakage current above the sensitivity setting of the RCCB. See it here:
                        Click image for larger version  Name:	rccb.png Views:	0 Size:	132.9 KB ID:	2543961

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                          #13
                          Originally posted by topgone View Post

                          Your RCCB will function as a summation of all the current passing thru it-->all should sum up vectorially to zero. Any current that will not be sensed by the breaker will be treated as "leakage" and it's up to the breakers sensitivity to either trip or not(I sensitivity >30ma)! Not wiring the neutral (if load does not need a neutral) means there will be no current thru it even if you wired it in. Test button simply simulates a leak on the trip circuitry of your breaker by allowing a small amount of current to pass outside of you CB's summation CTS, a resistor of a value just enough to imitate a leakage current above the sensitivity setting of the RCCB. See it here:
                          Click image for larger version  Name:	rccb.png Views:	0 Size:	132.9 KB ID:	2543961
                          But the test circuit is between pole 5 and neutral only, that means a valid complete circuit happens only pole 5 and neutral and not with any other poles. Then, how test circuit gets closed when only connecting 3 phases.

                          I have used multimeter to check in which poles the test circuit exists and i found the same as I said above.

                          I think you got my point.

                          Sent from my Redmi 3S using Tapatalk



                          Last edited by Abhi; 11-11-19, 09:47 PM.
                          [COLOR="#008000"]Insearch of clear concepts[/COLOR]

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                            #14
                            In order for the test button to work, you need a neutral on the source side here which is missing:


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                              #15
                              Originally posted by mbrooke View Post
                              In order for the test button to work, you need a neutral on the source side here which is missing:


                              But without connecting neutral point, the test button is working. How?
                              [COLOR="#008000"]Insearch of clear concepts[/COLOR]

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