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Grounds & Neutrals on 1 bus bar in transfer switch

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  • Grounds & Neutrals on 1 bus bar in transfer switch

    I was looking over the installation of my 7043 generator and the RXSW200A3 transfer switch this morning. I noticed there were 4 conductors in the neutral bar in the transfer switch, but there are only 3 cable assemblies entering the transfer switch---The feed from the meter (n1/n2, & neutral), the feed from the generator (e1/e2, neutral & ground), and the feed into the house (t1/ t2, neutral & ground). I traced everything out and then I realized the electrician has both the neutral and the ground from the t1/ t2 cable that goes into the house terminated in the neutral bar in the transfer switch. I called him and he said that being that the transfer switch is now the first disconnect, it is permissible to mix neutrals & grounds, and the neutral & ground bus bars are bonded together there by that pre installed green wire anyway. I know the neutrals & grounds were mixed in my main breaker panel in the house, but being that the main panel was now going to be a sub panel, he separated them, removed the bonding connector from the neutral bar to the breaker box case and installed a separate ground bar. Does this sound like it is OK ???
    Last edited by Rongold; 2 weeks ago.

  • #2
    Without having a qualified person inspecting the job, I can say that what you've described is essentially correct. I have a "whole house" generator system and worked with my licensed contractor installing and having it inspected. The original three-wire service feed to the original breaker box was removed and replaced with a three-wire feed to the "utility" disconnect in my 200A transfer switch. All grounding cables from the ground rods were moved to the transfer switch. All neutral-ground bonding in the original breaker panel was removed and the transfer switch was inspected to prove that it had proper bonding. Proper connections were made from the ground bus in the transfer switch to the now-isolated ground bus in the breaker panel. Equipment ground (green) wiring from the house is connected to the isolated ground bus in the breaker panel.

    Skip Douglas
    Last edited by SkipD; 2 weeks ago.
    Skip Douglas

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    • #3
      Originally posted by SkipD View Post
      Without having a qualified person inspecting the job, I can say that what you've described is essentially correct. I have a "whole house" generator system and worked with my licensed contractor installing and having it inspected. The original three-wire service feed to the original breaker box was removed and replaced with a three-wire feed to the "utility" disconnect in my 200A transfer switch. All grounding cables from the ground rods were moved to the transfer switch. All neutral-ground bonding in the original breaker panel was removed and the transfer switch was inspected to prove that it had proper bonding. Proper connections were made from the ground bus in the transfer switch to the now-isolated ground bus in the breaker panel. Equipment ground (green) wiring from the house is connected to the isolated ground bus in the breaker panel.

      Skip Douglas
      Mine is just like yours, except he has both the neutral and the ground for the t1/t2 cable assembly connected to the neutral bus in the transfer switch. The neutral bus is then bonded to the ground bus using that short piece of green insulated wire that comes factory installed. It was already inspected by the electrical inspector for my county, so I would assume that it is wired correctly. It just seemed odd that there are only 3 cable assemblies going into the transfer switch, but there are 4 conductors in the neutral bus bar. I think the main reason he did this was that in the ground bus bar, there are no holes large enough for the t1/t2 ground conductor. The holes are much larger in the neutral bus bar.
      Last edited by SkipD; 2 weeks ago.

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      • #4
        From what you have described what he did is correct. The only thing you did not describe is where is the grounding electrode conductor bonded ( the wire from the ground rod). Code calls for the bonding of the neutral and the grounding electrode conductor at or before the first disconnecting means. Also the neutral and the equipment ground must be separated and isolated in the generator.
        Sure it will work.... I saw it on YouTube

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        • #5
          Originally posted by ceb58 View Post
          From what you have described what he did is correct. The only thing you did not describe is where is the grounding electrode conductor bonded ( the wire from the ground rod). Code calls for the bonding of the neutral and the grounding electrode conductor at or before the first disconnecting means. Also the neutral and the equipment ground must be separated and isolated in the generator.
          Hi CEB,

          The neutral bar and the ground bar are bonded inside the transfer switch which is now the first disconnecting means. The ground rod is connected to the ground bar inside the transfer switch. The neutral and equipment ground ARE separated inside the generator---The neutral is connected to the neutral bar and the equipment ground is connected to the ground lug. There is NO bonding wire between them inside the generator. The only place they are bonded together is inside the transfer switch, which is now the first disconnect.


          RON
          Last edited by Rongold; 2 weeks ago.

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          • #6
            Well you found someone to do a correct install... now go by a loto ticket
            Sure it will work.... I saw it on YouTube

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            • #7
              Originally posted by ceb58 View Post
              Well you found someone to do a correct install... now go by a loto ticket
              Well, they ALMOST did a correct install. I checked the 6 wire control cable this afternoon. The electricians used some aftermarket 7 wire cable whose colors DO NOT match the Generac colors, and he had the "0" & the "12 volt dc" wires reversed. One guy hooked them up in the transfer switch and the other guy hooked them up in the generator. I guess they got their signals mixed up. The generator has not been activated or run yet, so I guess no damage was done. I wonder what problem might have shown up with those 2 wires reversed ??? Luckily they didn't mix the HV & LV wires !!!

              RON

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              • #8
                Originally posted by Rongold View Post

                Well, they ALMOST did a correct install. I checked the 6 wire control cable this afternoon. The electricians used some aftermarket 7 wire cable whose colors DO NOT match the Generac colors, and he had the "0" & the "12 volt dc" wires reversed. One guy hooked them up in the transfer switch and the other guy hooked them up in the generator. I guess they got their signals mixed up. The generator has not been activated or run yet, so I guess no damage was done. I wonder what problem might have shown up with those 2 wires reversed ??? Luckily they didn't mix the HV & LV wires !!!

                RON
                Ron, now is the time to find out if the 7-wire cable is safe to use for the purpose. My concern is the insulation rating for the wires in the cable, If the cable is designed for thermostat use, for example, you want it replaced immediately. What you need is a cable (or individual wires) with insulation rated at 600V or better on each and every wire in the group.
                Skip Douglas

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                • #9
                  Originally posted by SkipD View Post
                  Ron, now is the time to find out if the 7-wire cable is safe to use for the purpose. My concern is the insulation rating for the wires in the cable, If the cable is designed for thermostat use, for example, you want it replaced immediately. What you need is a cable (or individual wires) with insulation rated at 600V or better on each and every wire in the group.
                  Hi Skip,

                  No, it's not thermostat wire. The insulation is fairly thick. I asked him about it and he said it was rated at 600 volts, but the colors do not match the generator & transfer switch colors.

                  RON

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                  • #10
                    Originally posted by Rongold View Post

                    Hi Skip,

                    No, it's not thermostat wire. The insulation is fairly thick. I asked him about it and he said it was rated at 600 volts, but the colors do not match the generator & transfer switch colors.

                    RON
                    That's good news. Now what I would do is mark up the wiring drawings to show the actual colors and also make a page of notes that would include cable colors and connections. Ten years from now that could prevent significant confusion.
                    Skip Douglas

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