A few electrical questions

Discussion in 'Electrical and Wiring' started by Quattro, Mar 12, 2007.

  1. Mar 12, 2007 #1

    Quattro

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    My main service panel has one neutral/ground buss bar. It's full, and I need to clean it up because there are instances where grounds and neutrals are combined under one screw. This passed inspection when I bought the house, but I have been finding lots of things that our inspector missed...

    QUESTION 1:
    Can I buy a separate ground bar, screw it to the main panel, and move all the ground wires to it? That will free up lots of space on the neutral panel so each circuit can have it's own screw.

    QUESTION 2:
    Should that ground bar be attached to what will then be the "neutral only" bar with a heavy-gauge jumper?

    Thank you!
     
  2. Mar 12, 2007 #2

    Quattro

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    removed to clarify
     
  3. Mar 12, 2007 #3

    JoeD

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    1. If by tandem breaker you mean one that takes up only one slot then no tandem breaker. A double pole 240 volt breaker would be fine. In some case they are required.

    2. Yes can do that. One neutral per screw is a requirement for neutral wires.

    3. The additional ground bus has nothing to do with the fact that the sub panel must be connected with a proper size ground wire. The ground bus itself needs no connections. It grounds to the frame of the main panel when it installs.
     
  4. Mar 13, 2007 #4

    Quattro

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    Hey JoeD, thanks for the help.

    1. I meant 2-pole breaker, with a connected handle (forgot the term for this).

    2. That's what I thought...will do.

    3. So the sub-panel does not need a ground feeder wire running to the main panel ground bus? The sub-panel grounding bus is (obviously) screwed to the sub-panel box itself.
     
  5. Mar 13, 2007 #5

    Quattro

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    OK, a little more info:

    - taking a voltage reading between the two circuits in question, I get 245V. According to another resource, this means the circuits are on opposite phases, and I shouldn't have a problem with the shared neutral. Is this correct?

    Now, looking at the existing neutral/ground bus on the 20-space main panel:

    - there are only 16 or 17 locators. How the heck is a guy supposed to have enough spaces on the bar to accomodate 20 circuits? Even if only 1/4 of the breakers have shared neutrals, that's still 15 inidividual spaces needed for neutral landings. That leaves 1 or 2 for ALL the ground wires? This just doesn't seem right.
    Looking more closely at the ground/neutral bar reveals there are smaller holes right beneath the regular holes for securing the neutral wires. But, as far as I can tell, there is no way to secure a ground wire in these smaller holes. What are these for? I might have to snap a picture to reveal what I'm talking about here...if this is too confusing.

    Thanks for the help.
     
  6. Mar 13, 2007 #6

    Quattro

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    Pictures!

    The overall main and sub panel:
    [​IMG]

    A little closeup of the wire entries:
    [​IMG]

    The FULL neutral/ground bus:
    [​IMG]

    Another shot:
    [​IMG]
     
  7. Mar 13, 2007 #7

    Quattro

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    The "mystery holes" on the neutral/ground bus under the regular screw-clamp holes:
    [​IMG]
     
  8. Mar 13, 2007 #8

    glennjanie

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    The sub-panel is connected to the main with "compression fittings" which I personally don't trust for grounding. I wold keep the big green wire and move it to the higher (horizontal) bus bar along with the other ground wire that is connected to the vertical one.
    I like the grounds being tied to the copper pipe but I would also want a driven ground rod outside.
     
  9. Mar 13, 2007 #9

    JoeD

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    The sub panel needs a ground wire from the main panel. I thought you meant connecting a wire from the existing ground bus to the new one you want to install in your main panel.
     
  10. Mar 13, 2007 #10

    JoeD

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    I also see a couple of breakers with two wires under the screw. Some breakers are rated two wires, some are not. I don't know which type yours are but that could be ans issue if they are not two rated.
     
  11. Mar 13, 2007 #11

    Quattro

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    This is what I meant! I need more room in the existing ground/neutral bus in the main panel. There isn't enough room for each neutral to have it's own spot. Not even close! Why did they do this?

    And you're right on the double-wired breakers. There are two. Both were done by (I assume) the previous owner or original owner.The one on the mid-left is the doorbell transformer. The upper right is the washing machine and something else. I need to trace what the "something else" is. There is an open slot at the bottom left (breaker, no wire), so it can me moved there I suppose.

    Thanks!
     
  12. Mar 14, 2007 #12

    Square Eye

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    The green wire is the ground connection from the main panel to the sub panel. And the ground wire connection to the grounding rod is made in the meter base.

    A ground jumper from the original grounding buss would be necessary to the new grounding bar as the main panel doesn't seem to be bonded.
     
  13. Mar 15, 2007 #13

    glennjanie

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    One more suggestion, Quattro:
    You could move the wires from the sub-panel's vertical bar to the horizontal bar (grouping your bare ground wires again), then move that vertical bar over to the Master panel. That should give you sufficient spaces.
    I still insist the green wire needs to go to the sub-panel horizontal bar.
    I can see a large bare wire comming out of the master panel, possibly going out to the meter base and the ground rod.
    Glenn
     
  14. Mar 15, 2007 #14

    Quattro

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    I have been told over and over that the sub-panel ground and neutral should NOT be connected. The neutral floats in that panel, and is connected by #6 to the main panel neutral buss.

    The main panel has a ground rod AND a bundled ground attached to the nearest copper pipe (which is connected to the rest of the copper pipe in the house).

    Square Eye: how would I know if the main panel neutral buss is bonded or not? Thanks!
     
  15. Mar 15, 2007 #15

    JoeD

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    The ground bus should be bonded to the metal of the panel box. There should not be a need to jumper the two busses together. If the original bus is not bonded then it was meant to be a neutral buss only and a ground bus should have been installed separately.
     
  16. Mar 15, 2007 #16

    Quattro

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    If by "bonded" do you mean screwed to the panel with a long brass screw? In that case, it is bonded.
     
  17. Mar 16, 2007 #17

    glennjanie

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    A bonded panel has a piece of rigid conduit through the side where your ground wire comes out and goes to the ground rod; there would be a bushing on that conduit that is screwed tight against the box and has a seperate hole on the side of it for the ground wire to go through, and a screw to tighten down on the wire. Its called a bonding bushing and it grounds the box independent of the grounding bar.
    The connection to the sub-panel appears to be made of EMT conduit with connectors attached by a screw in the side of them. This is not acceptable for a grounding path between the two panels. Therefore, the green wire still needs to go from neutral/ground buss bar to the other neutral/ground buss bar.
    Glenn
     
  18. Mar 17, 2007 #18

    Square Eye

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    I suppose the same words could be interpreted many ways.:)

    A newer main panel will have a Bonding screw included with it. Your panel may be have been manufactured before this was the case. The bonding screw passes through the neutral buss and attaches directly into the back of the panel. This is necessary at the main panel. The option is there to use this same panel as a sub-panel by not attaching the bonding screw. This leaves the neutral floating in the panel and requires a ground wire from the ground bar back to the main panel.

    In your case.. I don't know wether your panel's neutral buss is bonded to the panel or not. It looks like an older panel and I really can't tell from here. A neutral jumper won't hurt a thing.
     
  19. Mar 19, 2007 #19

    Quattro

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    Hey guys,

    yes, the main panel is screwed to the back of the panel. It's a brass screw. I'm going to look around for a good place to mount that auxillary ground buss now!
     
  20. Mar 30, 2007 #20

    AndyD5

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    You're looking at an older style square D panel you are correct that each ground an neutral should have it's own screw position you can put in a secondary bus for the neutrals they have them that clamp ontop the existing or just screw right into the frame of the panel a branch circuit just needs grounding period it doesn't have to be grounded back to the main panel it can be grounded to a nearby fully functional coper water line anywhere in the house my branch box is ground clamped to the supply line to the toilet nearby. I don't know the codes there but here the water supply line is the ground in every house. the stranded heavy guage wire provides ground to the main panel.
     

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