enter image description hereOk...... I had an older spa pump that went out. I also replaced the spa pack. The old spa pack had a GFCI breaker in it and the new one does not. So now I have to add gfci protection to the spa via a gfci breaker. The older main panel (square D) does not make gfci breakers for that style of panel (1980's). So I elminated the hot tub from the main and moved it into an under utilized already existing sub panel.

Here is where I am now lost..... the sub has only one bus bar, all wired attached are grounds, there is NO floating neutral bus bar. I know I can NOT run the breaker (which has a built in "coiled" neutral wire to the ground bus bar or I create a parallel circuit which will feed back current and will not trip the gfci.

So....... Question 1: Can I ground the hot tub in the subpanel and run the neutral into the main panel and attach it there ? Will that create a parallel circuit? Will that prevent the gfci breaker from tripping?

Question 2: If that will not work....... OPTION A: is there a way to ground the subpanel, (grounding rod) and mount a new bus bar to ground box and use the other bus bar as a neutral bar. OR OPTION B: how do I create a neutral bus bar in the subpanel...... (if this is the option I need details) I know it needs to float, but where would it connect to in the main panel ? What gauge wire would be needed?

More info..... the main panel does not have a Main disconnect breaker, the sub panel is being fed from a 60 AMP breaker in the main panel that has two wires from the breaker to the subpanel lugs, a ground and a neutral in the main panel. The current subpanel (also Square D) bus is a ground bus running to the main panel bus.

Thank you for any and all information, I am NO electrician so any help is greatly appreciated.

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    I'm confused... How many wires are there between the panels, 3 or 4? Are all the wires insulated, or are there one or more bare wires? What color is the insulation that is on the wires? Where are the wires terminated in the main, and where are they terminated in the second panel? Photos would help.
    – Tester101
    Commented Aug 9, 2015 at 17:53
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    Sounds like you're going to have to run a grounded (neutral) conductor between the panels, and install a grounded (neutral) bar in the second panel. But I can't be sure based on your description.
    – Tester101
    Commented Aug 9, 2015 at 18:04
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    Like @Tester101 said, you need 4 conductors from the main panel to the sub (2 "hot", 1 grounded/"neutral," and 1 green or bare grounding conductor). Looking at your picture, that bus bar on plastic standoffs in the lower right (upper right if you rotate the picture) is the neutral bar if you remove that brass bonding screw that is connecting it to the panel. So you'll also need to install a grounding bus bar, bonded to the panel, and connect the neutrals and grounding wires to their separate bus. Grounded (neutral) and grounding must be isolated in a sub-panel (bonded in main panel). Commented Aug 9, 2015 at 18:42
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    @Robert Can you read the printing on the black wires feeding the panel, and tell us what size they are? There should be a number followed by "AWG". It should also say if it's copper (CU) or aluminum (AL), which we'll need to know.
    – Tester101
    Commented Aug 9, 2015 at 18:50
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    Just a final note--looking at your picture, there are some ground wires poking so far through the clamps in that bus bar that they're touching (or nearly touching) the side of the panel. You want to be sure you don't do that with the neutral wires you connect there after you remove the brass bonding screw. If the ends of those wires touch the panel, you'll be bonding your grounded (neutral) and grounding conductors in the subpanel, which is against code. Commented Aug 9, 2015 at 23:33

1 Answer 1


It's difficult to tell from the photo if there's even a grounding conductor run along with the two ungrounded (hot) conductors, so you'll have to verify that before you go shopping for supplies. You'll also have to verify that the ungrounded (hot) conductors are the proper size. You said the panel is fed through a 60 ampere breaker, so you'll need at least 6 AWG copper conductors (solid or stranded, it makes no difference).


Here's what you're going to need.

  • A grounding bus bar.
  • 6 AWG copper THWN wire with white or gray insulation, long enough to reach from the main grounded (neutral) bar to second panel grounded (neutral) bar.
  • 6 AWG bare or green copper conductor, long enough to reach from the main grounding bar to the second panel grounding bar (which you'll install).

If the current ungrounded (hot) conductors are undersized, you have a couple choices. You can replace them, with appropriate conductors. Or you can install a smaller feeder breaker in the main panel, and down size the grounded and grounding conductors accordingly.


Once you have the supplies, here's what you're going to do.

  • Remove the brass bonding screw from the existing bus bar in the second panel.
  • Install the grounding bus bar (the one you purchased), in the panel.
  • Move all the grounding conductors from the old grounding bus, to the new grounding bus bar.
  • Pull the required conductors between the panels.
  • Connect the grounded (neutral) conductor to the grounded (neutral) bar in the main panel.
  • Connect the grounding conductor to the grounding bar in the main panel.
  • Connect the grounded (neutral) conductor to the grounded (neutral) bar in the second panel.
  • Connect the grounding conductor to the new grounding bar in the second panel.
  • Connect the grounded (neutral) pigtail from the GFCI breaker, to the grounded (neutral) bar in the second panel.

Now you should be all set.

NOTE: Depending on where the second panel is installed. You may need to install a grounding electrode, and bond the panel to it. Check with your local building department, to determine if this is required.

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