Little background before I ask question. I pulled a lines from main panel to outside subpanel, some 130 ft away. Put double pole regular breaker in the main panel (60A). In the sub panel I placed on 15A double pole GFCI breaker and one regular 15A sinle pole breaker. Single pole breaker line feeds to GFCI outlet. That outlet never trips, I can test it, I can reset it, I can put load on it, and no problem. I even tested it with outlet tester. No problems. Now if I turn on other double pole breaker, it trips immediately. If I leave that twisted wire from the breaker connected to the white bus, but disconnect white wire from my breaker, my breaker naturally does not trip. I measure voltage and it shows 282V between the poles on the breaker, and 141 between each of the poles and white bus. Then I thought, maybe the breaker is bad. So I took out double pole, and installed single pole GFCI breker, and same story with that one too. It immediately trips when I plug in white wire.

What else can I try and what could be the issue. I don't think that wire is damaged as pulling it was very smooth, and it is #6 AWG wire, and most of the wire is above ground.

Any ideas? How can I trouble shoot it further?

  • You're thinking backwards. The GFCI breaker in the second panel protects the branch circuit wiring connected to it, not the circuit feeding the panel. If it's tripping, there's a problem in the branch circuit.
    – Tester101
    Commented Mar 16, 2015 at 0:17
  • Where are you located? Your voltage readings are high if you're in the US. You should be around 240 volts and 120 volts respectively.
    – Tester101
    Commented Mar 16, 2015 at 0:21
  • Are the grounded (neutral) and grounding (earth) bars in the second panel isolated from each other? Is the second panel bonded to a grounding electrode?
    – Tester101
    Commented Mar 16, 2015 at 0:27
  • @Tester101: Located in Dallas, TX
    – epitka
    Commented Mar 16, 2015 at 0:39
  • @Tester101: I understand that it protects circuit in sub panel . The thing is, as soon as I plug in the breaker, and turn on the power it trips, but only when I connect white wire to the bus where other white wires are connected to. If only coiled white wire is connected to the bus it does not trip. From main panel I run 4 wires, black, red, white and green. Green is grounding connected to the grounding bus, white to neutral and black and red to line 1 and line 2 ports.
    – epitka
    Commented Mar 16, 2015 at 0:43

1 Answer 1


Figured it out. My mistake. The breaker has 3 slots and pig tail white wire. I assumed that I needed to run one more white wire and connect it to the middle slot and neutral bus, not just by the pig tail white wire. It turned out that I needed to connect only pig tail white wire to neutral bus. Unfortunately I misplaced the package for the breaker and did not read instructions prior to installing it.

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