New construction wiring test

Discussion in 'General Electronics Chat' started by jbrunton, May 3, 2013.

  1. jbrunton

    Thread Starter New Member

    May 3, 2013
    11
    0
    I've got a problem I'm trying to understand.

    I have a new house under construction and I've wired it myself and passed the rough-in inspection and I'm ready for the final inspection but I want to be assured there are no surprises when the final takes place.

    I have an extension cord plugged into a 20 amp GFIC at the temporary pole. Using the extension cord I plugged the bare wires into the extension cord (one circuit at a time) so that each circuit could be tested as well as outlets and switches. Every circuit has texted fine.

    I've now installed the breakers in the service panel and attached all hots, neutrals and grounds. Using the extension cord method I've attached a wire to a 20 amp breaker to back-feed the panel. The reason is - to test all circuits operating through the panel. The underground service line has not been installed yet so there is no danger to linemen.

    With the main breaker off and all breakers turned off I supply power to the panel but it trips the GFIC at the temporary pole. Using an Ohm meter I know the main bus isn't grounded so there is no problem there, and the main disconnect is off so it isn't sending power to the meter/disconnect outside.

    I'm wondering if it's the nature of the GFIC to trip in this instance? I'm assuming you can back-feed through a normal 20 amp single pole breaker.

    Something I haven't tried is to back-feed the panel using my generator. It has 20 amp breakers but they are not GFIC breakers.

    Any suggestions would be appreciated.
     
  2. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    How are you connecting to the panel? The panel has 2 bus bars are you connecting to both of them? Give us a little more info.
     
  3. joeyd999

    AAC Fanatic!

    Jun 6, 2011
    2,674
    2,724
    Call me silly, but, regardless of my vast and unlimited knowledge of all things electrical/electronic, wiring/troubleshooting my own house based on internet advice is something that I don't think I'd ever do.

    That you haven't the knowledge to understand why the GFIC is tripping, or the skill/experience to figure it out, tells me you should proceed with *extreme* caution. Your's and your family's lives are at stake. Just saying...
     
  4. jbrunton

    Thread Starter New Member

    May 3, 2013
    11
    0
    I have a power strip plugged into the extension cord. I have a piece of #12 wire I plug directly into the powerstrip (white wire in long side, black in short side and bare in ground spot). The other end of the wire attaches to the service panel - white & ground to the neutral bus and the hot to a 20 amp breaker. with the 20 amp breaker off - I flip the power switch on the strip and the GFIC at the temporary pole trips.

    Of course I use extreme caution - I have taken a class in residential wiring and this is the second house I've wired. I have a healthy respect for electricity!

    In Tennessee a final inspection is performed and THEN the electric company comes and turns on the power. But here in Kentucky when a final inspection is ordered the power is turned on and then the inspector comes - and tests all outlets, breakers, GFICs, and switches. For that reason, I want to test everything before hand so there are no surprises.
     
  5. jbrunton

    Thread Starter New Member

    May 3, 2013
    11
    0
    through-out the house all face plates and switch covers are installed.
     
  6. Meixner

    Member

    Sep 26, 2011
    116
    21
    Try connecting without the power strip.
     
  7. jbrunton

    Thread Starter New Member

    May 3, 2013
    11
    0
    It still trips. Using a powerstrip saves time walking back and forth to the temporary power pole to reset it.
     
  8. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    First thing that comes to mind is are the neutral and hot reversed somewhere on your cord/strip. Take a meter and check voltage between the long slot on your strip and the ground of the panel, should be zero. Now do the short slot to ground of the panel, you should see your 120v.
     
  9. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    A bad connection (arcing) here will cause GFCI trip
     
  10. jbrunton

    Thread Starter New Member

    May 3, 2013
    11
    0
    gerty - I have the black wire in the short slot of the powerstrip connected to the breaker. The white wire is in the long slot and is connected to the neutral bus with the bare ground wire.

    The power strip and wires don't move when I flip the switch so there should be no arcing.
     
  11. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    Did you see the post where I asked you to meter the voltage? At this point we're not 100% sure the black wire needs to to go into the short slot.
     
  12. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    With your setup, the new panel in the house has become a secondary panel. White wires should NOT be connected to the same strip as ground in a secondary panel.
     
  13. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    100% correct...But...I believe, at this point, the new panel is the only panel other than the temporary service.

    Edit..I could be wrong...I was once before.
     
  14. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    If the temporary construction panel was installed properly, it will have the white wire tied to the ground wire and have a driven rod. The new panel in the house should also have a ground rod with a bus wire going to the ground bus AND the ground bus tied to the white wire bus. 2 grounds can confuse a GFI since some of the current from the house is making its way to earth rather than returning through the GFI on the temp pole.

    On edit.... Just capacitive coupling within the house romex can cause enough current to trip a GFI if all of it doesn't go back through the GFI.
     
  15. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    In one of his posts he makes it sound like he's tripping the breaker in the plug strip, although he doesn't actually say the words
    I believe he has a wire crossed somewhere between the panels
     
  16. jbrunton

    Thread Starter New Member

    May 3, 2013
    11
    0
    The problem is with trying to back feed the service panel using the GDIC at the service panel. For some reason it will trip the GFIC when the load is applied. When I got home from work this evening I did the same test but instead of using the GFIC at the temporary pole, I used my generator. It worked like a charm! It's now getting late so I'll go about doing complete testing this weekend.

    Thanks for all your input!
     
  17. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    drop the bond from neutral, it represents a second ground to it's source.
     
  18. jbrunton

    Thread Starter New Member

    May 3, 2013
    11
    0
    To follow-up this discussion:

    I had tested the service panel by back-feeding my generator through the outside A/C breaker (no service connected). I was able power all circuits except arc-fault breakers. They would trip whereas normal circuits would not. I could use my meter at each location and check for power.

    Fast forward to yesterday - the power company came and connected my service. Being a Friday afternoon of a three day weekend the county inspector wasn't going to make it out. It's a good thing actually as I have a problem. None of the 17 arc-fault breakers work. They all trip as a load is applied. This has me totally stumped. I understand how one could be a problem but all 17?

    It's Saturday and I've got till Tuesday to get this figured out.

    I've decided I should disconnect all arc fault circuits and re introduce them one at a time.

    Any other suggestions would be greatly appreciated!
     
  19. Meixner

    Member

    Sep 26, 2011
    116
    21
    I hope you can find the problem, Please don't feel slighted if you don't get many replies. This board is kind of dead on weekends and holidays. Good luck.
     
  20. jbrunton

    Thread Starter New Member

    May 3, 2013
    11
    0
    BillB3857 is correct, I believe. The service disconnect has the neutral and ground bonded so the service panel needs the neutral and ground isolated. I didn't do this initially and none of my arc-fault breakers worked. I even removed every breaker, neutral and ground wire save one arc-fault breaker and I connected that to the freezer outlet since it's in the same room and only one outlet in the circuit. No dice - the arc-fault breaker trips when a load is applied.

    In fact, I took one arc-fault out to the service disconnect panel and added that (it has 4 slots for breakers) and connected to a GFIC located just below the disconnect panel. Plugged a drill into that and it immediately tripped the arc-fault breaker.

    So, taking BikkB3857's advice, I removed all ground wires from the neutral buses and isolated the ground from the neutral. That didn't change a thing. All arc-fault breakers trip immediately under load...
     
Loading...