Announcement

Collapse
No announcement yet.

Two switchboards

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    #16
    Originally posted by hhsting View Post
    If I had decision to make I would get busbar separate outside of swbd and have one GEC from swbd #1 , one GEC to swbd #2 to outside busbar and then have bonding jumpers from the busbar to GE.

    But I am being questioned as to the installation of neutral bar as common bus in swbd #1 by the owners where is it in NEC code violation. Its accessible and bonding jumpers are going to GE and GEC come from swbd #2 to swbd #1 neutral bar. It complies per nec 250.64(F)(3) so as long as neutral bar in swbd #1 is 0.25 in by 2 in.
    Well from an authority prospective the plate is not an equipment ground or neutral bar in a panel nor a bar inside a dry transformer. I do not see the issue of providing a bonding plate/bar in the electric room provided for this purpose.

    An authority at times needs to make this call

    Comment


      #17
      Originally posted by david View Post
      Well from an authority prospective the plate is not an equipment ground or neutral bar in a panel nor a bar inside a dry transformer. I do not see the issue of providing a bonding plate/bar in the electric room provided for this purpose.

      An authority at times needs to make this call
      What providing bonding plate/bar in fire pump room instead of electric room?

      Sent from my SM-G935U using Tapatalk

      Comment


        #18
        Originally posted by hhsting View Post
        What providing bonding plate/bar in fire pump room instead of electric room?

        Sent from my SM-G935U using Tapatalk
        The assumption was #1 service was the larger service bonding jumpers from a plate at #1 location would be sized also correct for #2 service

        Comment


          #19
          Originally posted by david View Post
          The assumption was #1 service was the larger service bonding jumpers from a plate at #1 location would be sized also correct for #2 service
          I mean separate busbar out of service equipments per nec 250.64(f)(3) in accessible location in fire pump room location of swbd #2 instead of electric room.

          Sent from my SM-G935U using Tapatalk

          Comment


            #20
            250.6 Objectionable Current. (A) Arrangement to Prevent Objectionable Current. The grounding of electrical systems, circuit conductors, surge arresters, surge-protective devices, and conductive normally non–current-carrying metal parts of equipment shall be installed and arranged in a manner that will prevent objectionable current
            two neutral to ground bonds on one electrical system(the same transformer)at two separated areas connected by conductive paths, i think this is your real problem.

            Comment


              #21
              Originally posted by Wire-Smith View Post
              two neutral to ground bonds on one electrical system(the same transformer)at two separated areas connected by conductive paths, i think this is your real problem.
              Dont follow. Neutral to bond are at service disconnects and 250.50 all grounding electrodes need to be bonded together in building. If GEC are installed per nec 2014 article 250.64(f)(3) with busbar in electric room outside of service equipment would that create objectionable current?
              Last edited by hhsting; 01-25-19, 09:27 PM.

              Comment


                #22
                Originally posted by hhsting View Post
                Dont follow. Neutral to bond are at service disconnects and 250.50 all grounding electrodes need to be bonded together in building. If GEC are installed per nec 2014 article 250.64(f)(3) with busbar in electric room outside of service equipment would that create objectionable current?
                you have one transformer feeding two panelboards and both have a neutral to ground bond correct?

                if so, everything grounded and bonded to both of those panels is effectively a parallel neutral and will carry part of the neutral current from either of the panelboards. its not a big deal if the panels are side by side, but in two separate areas, i see potential problems(sparking ground connections, shock hazards, etc.) and would red tag it if i was the ahj and would not do it if i was the contractor.

                Comment


                  #23
                  Originally posted by Wire-Smith View Post
                  you have one transformer feeding two panelboards and both have a neutral to ground bond correct?

                  if so, everything grounded and bonded to both of those panels is effectively a parallel neutral and will carry part of the neutral current from either of the panelboards. its not a big deal if the panels are side by side, but in two separate areas, i see potential problems(sparking ground connections, shock hazards, etc.) and would red tag it if i was the ahj and would not do it if i was the contractor.
                  You mean attached sketch cause objectionable current? If yes then how are the two service swbd grounded and bonded?
                  Last edited by hhsting; 01-25-19, 09:48 PM.

                  Comment


                    #24
                    you could eliminate the problem several ways

                    1.) disconnect(s) before panelboards, if you use one then that's where your only main bond will be. if you use two, group the disconnects and those will be your only main bonds.

                    2.)group panelboards beside eachother
                    Last edited by Wire-Smith; 01-25-19, 09:55 PM.

                    Comment


                      #25
                      Originally posted by Wire-Smith View Post
                      you could eliminate the problem several ways

                      1.) disconnect(s) before panelboards, if you use one then that's where your only main bond will be. if you use two, group the disconnects and those will be your only main bonds.

                      2.)group panelboards beside eachother
                      How about attach sketch swbd#1 exterior wall fire pump room while swbd #2 inside fire pump room next to each other. Swbd #2 is for fire pump.

                      Sent from my SM-G935U using Tapatalk

                      Comment


                        #26
                        Originally posted by hhsting View Post
                        Dont follow. Neutral to bond are at service disconnects and 250.50 all grounding electrodes need to be bonded together in building. If GEC are installed per nec 2014 article 250.64(f)(3) with busbar in electric room outside of service equipment would that create objectionable current?
                        As long as the bonding jumpers to building steel, water system, CEE, or any other electrode used to make up the grounding electrode system, sized for the largest service i do not see a violation

                        I do not think it matters if the Plate is in the area of service one or service two. By going to a boding plate with both services you have come as close as possible to a single point grounding electrode system as two service (laterals) will allow

                        IMO at least,

                        Comment


                          #27
                          Originally posted by hhsting View Post
                          How about attach sketch swbd#1 exterior wall fire pump room while swbd #2 inside fire pump room next to each other. Swbd #2 is for fire pump.

                          Sent from my SM-G935U using Tapatalk
                          i would be comfortable with that, but would probably run a big bonding jumper from one panelboard to the other just for good measure and would personally still prefer one main disconnect(or two pretty much bolted together), although your illustration would be what i consider more inline with the more standard industry practice.

                          Comment


                            #28
                            Originally posted by david View Post
                            As long as the bonding jumpers to building steel, water system, CEE, or any other electrode used to make up the grounding electrode system, sized for the largest service i do not see a violation

                            I do not think it matters if the Plate is in the area of service one or service two. By going to a boding plate with both services you have come as close as possible to a single point grounding electrode system as two service (laterals) will allow

                            IMO at least,

                            wait until one of these days you run across a building with a double bond and you lose one of the service neutrals, you'll see things like flex sparking against conduits, pipes. and it could also happen without losing a neutral but would likely not cause a problem unless you have decent neutral current, but then again it doesn't take much current to do a lot of damage under the right circumstances. i have heard of people feeling circulating ground current in the shower (albeit metal plumbing, but you get the hint).

                            Comment


                              #29
                              Originally posted by Wire-Smith View Post
                              i would be comfortable with that, but would probably run a big bonding jumper from one panelboard to the other just for good measure and would personally still prefer one main disconnect(or two pretty much bolted together), although your illustration would be what i consider more inline with the more standard industry practice.
                              I do have swbd #1 enclosure bonded and swbd #2 enclosure bonded together. See attach sketch. Would it still require bonding jumper in between?

                              Sent from my SM-G935U using Tapatalk

                              Comment


                                #30
                                Originally posted by hhsting View Post
                                I do have swbd #1 enclosure bonded and swbd #2 enclosure bonded together. See attach sketch. Would it still require bonding jumper in between?

                                Sent from my SM-G935U using Tapatalk
                                i didn't say it required it, just that i would do it.

                                although i believe it is required in patient care areas if that happens to be the location. (if they serve patient care areas)(517.14)

                                Comment

                                Working...
                                X