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    shunt trip breaker wiring

    can the wiring for a shunt trip breaker run in separate conduit from same panel ? or must they run in separate conduit? I havent installed many shunt trip breakers so I am trying to determine the best way to install.

    #2
    Originally posted by mannyb View Post
    can the wiring for a shunt trip breaker run in separate conduit from same panel ? or must they run in separate conduit?
    Separate conduit? Are you talking about the control wiring? I'm not following you.

    -Hal

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      #3
      Agreed: separate conduit or separate conduit?
      Master Electrician
      Electrical Contractor
      Richmond, VA

      Comment


        #4
        Originally posted by LarryFine View Post
        Agreed: separate conduit or separate conduit?
        I think the actual question is: MAY they be run with CCC, or MUST they be run with CCC. The only shunt-trip breakers I worked on were in the cabinets of the equipment controlling them, so I never gave that issue much thought.

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          #5
          As long as the control voltage is 120 I see no reason the control wiring can't be run in the same conduit as the current carrying conductors. There is nothing that says they must either.

          -Hal

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            #6
            Commercial kitchen fire-suppression systems, for example.

            Yes, the conductors may be run with other power conductors.

            As an aside, most shunt-trip breakers can not withstand continuous coil energization. If the tripping current comes from a circuit supplied by the shunt-trip breaker, it will automatically be protected.
            Master Electrician
            Electrical Contractor
            Richmond, VA

            Comment


              #7
              Originally posted by LarryFine View Post
              Commercial kitchen fire-suppression systems, for example.

              Yes, the conductors may be run with other power conductors.

              As an aside, most shunt-trip breakers can not withstand continuous coil energization. If the tripping current comes from a circuit supplied by the shunt-trip breaker, it will automatically be protected.
              Larry, how would you provide OCP for the control wiring if the shunt trip breaker has a 60-amp rating for OCP?

              Then, do you make any attempt to prevent the control wiring circuit from becoming de-energized and useless for operating the shunt trip?

              Comment


                #8
                Originally posted by OldSparks View Post
                I think the actual question is: MAY they be run with CCC, or MUST they be run with CCC. The only shunt-trip breakers I worked on were in the cabinets of the equipment controlling them, so I never gave that issue much thought.
                like you mention I never giave it much thought because it was already installed 120/208v> This will be a 3phase 480v breaker not sure if control will be 277v? I have only delt with 120/208 or 240v

                Comment


                  #9
                  Originally posted by oldsparky52 View Post
                  Larry, how would you provide OCP for the control wiring if the shunt trip breaker has a 60-amp rating for OCP?
                  Control wiring is permitted to tap into the controlled wiring. A fuse can always be added. I'd have to know your specific situation.

                  Then, do you make any attempt to prevent the control wiring circuit from becoming de-energized and useless for operating the shunt trip?
                  Again, I'd have to know about your installation to answer more.
                  Master Electrician
                  Electrical Contractor
                  Richmond, VA

                  Comment


                    #10
                    Originally posted by LarryFine View Post
                    Control wiring is permitted to tap into the controlled wiring. A fuse can always be added. I'd have to know your specific situation.


                    Again, I'd have to know about your installation to answer more.
                    Hypothetically, a 60-amp circuit using a shunt trip breaker for quick shut-down. The shunt trip operator (I mean this to be the mushroom switch or pull station or whatever) is 50' away from the panel.

                    Since the operator is out of the enclosure for the breaker, I believe you will need OCP sized to the control conductors. If you install a fuse, and the fuse is disabled somehow, the shunt trip will not work and you won't know it until you try to use it.

                    So what I'm trying to ascertain is whether you believe this possibility to be significant enough to try to prevent it from occurring (the unknown failure of the control circuit).

                    Comment


                      #11
                      If you need to be that sure, then use a contactor instead, wired so it drops out under emergency conditions.
                      Master Electrician
                      Electrical Contractor
                      Richmond, VA

                      Comment


                        #12
                        My experience is with 120/208 and the control voltage is derived from the same circuit the breaker protects, usually 20A. So, not only does that handle the requirement that the shunt trip coil not be continuously energized, it also provides some assurance that the control voltage will be present, unlike if it were provided by another circuit.

                        If the control circuit must be such that the reliability is compromised by factors such as separate OCP, you probably shouldn't be using a shunt trip breaker. Use a contactor wired to latch through the EMO button. This also gives the advantage of using LV control if desired.

                        -Hal

                        Comment


                          #13
                          Originally posted by LarryFine View Post
                          If you need to be that sure, then use a contactor instead, wired so it drops out under emergency conditions.
                          Agreed, so ...

                          Kitchen equipment being left on after the shut down button is depressed is ... no big deal?

                          A gas station E-Stop does not work because the shunt trip control circuit dropped out (yes I've seen people use shunt trips for this)?

                          Personally I generally don't like to use shunt trip breakers for e-stops or critical got to shut it down equipment.

                          Comment


                            #14
                            Originally posted by oldsparky52 View Post
                            Agreed, so ...

                            Kitchen equipment being left on after the shut down button is depressed is ... no big deal?
                            To me, it is a big deal. Unless there are already shunt-trip breakers installed (I wire both existing and new systems), I usually install contactors for appliances.

                            Failing to energize is less of a hazard than failing to de-energize to me.
                            Master Electrician
                            Electrical Contractor
                            Richmond, VA

                            Comment


                              #15
                              Originally posted by LarryFine View Post
                              To me, it is a big deal. Unless there are already shunt-trip breakers installed (I wire both existing and new systems), I usually install contactors for appliances.

                              Failing to energize is less of a hazard than failing to de-energize to me.
                              +1 (when I was working )

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