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Electrical help...need help with grounding..

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  • Electrical help...need help with grounding..

    Morning,

    I replaced a sub power panel in the garage for one with more beakers. In doing that, I somehow failed to ground the box or something. If I touch to machines now, I get a slight buzz in the fingers.

    I am missing something. I assume the sub panel is not grounded. How to ground it properly?

    This is the box I purchased:
    http://www.homedepot.com/p/Square-D-...125C/202495819

  • #2
    Hopefully someone who is familiar with code will weigh in, but from memory a subpanel should be "grounded" to the main panel, not to an independent ground.

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    • #3
      Since this is a sub panel there should be two bus bars in it. One should have all the ground wires connected to it and it should be
      screwed directly to the box so it makes electrical contact. The other should have all the neutral (white) wires connected to it and
      it should be electrically isolated from the box. Also check the main panel to make sure the ground is secure. In the main panel, there
      should be only one bus bar which has all the grounds and neutrals connected to it.
      Location: Long Island, N.Y.

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      • #4
        Originally posted by MTNGUN View Post
        Hopefully someone who is familiar with code will weigh in, but from memory a subpanel should be "grounded" to the main panel, not to an independent ground.
        That is correct. Also a sub-panel should have the ground and neutral bars physically and electrically separate, bonding jumper should be removed, neutral bar should have the screw that bonds it to the metal case, removed if present.

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        • #5
          Cue, a subpanel should have a completely separate ground buss in a subpanel and not be bonded to the neutral buss as in the main. The ground buss piece should be available from homey depot where you bought the panel. The neutral in the subpanel should not connect anywhere to the subpanel frame,(via a bonding screw) All the green or bare ground wires should connect to the grounding buss and all the white neutral wires should connect to the neutral buss . A separate ground wire of the appropriate size for your subpanel should run continuously back to the neutral/ground buss at your main which should go to a grounding electrode at your main. I don't have an NEC book handy but if you go online to Mike Holt's website and do a search on grounding you will find the relevant code section. Also check the polarity on any devices you have plugged in or if you accidentally misswired a receptacle . Also,depending on your jurisdiction,they want a separate grounding electrode at the sub. Hope this helps. Jim
          (sorry for the repeat info, the other guys are faster typists...)

          Comment


          • #6
            Originally posted by cuemaker View Post
            I assume the sub panel is not grounded. How to ground it properly?
            ]
            The ground wire coming into the sub panel should connect to the sub panel ground bus bar. The other end of that ground should be to the master panel.

            But we don't know what wiring you're got or how you hooked up it up.

            Also, I'm not sure it not being grounded is your problem (although make sure it is). Somehow there is a connection between something hot and the machine frame (which should be ground to the subpanel). you're basically touching a live circuit and current is flowing through you to earth ground. it gets a good enough connection and you might not be making any more cues

            I'd kill breaker at the main panel, all the breakers in the sub panel, and with a meter start figuring out whats connected to what.
            Last edited by Mcgyver; 10-24-2015, 11:59 AM.
            in Toronto Ontario - where are you?

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            • #7
              If the sub panel is in a separate building, a separate ground rod should be driven and connected to the subpanel ground system. A difference in electrical potential can develop from different grounding characteristics between the ground in the separate buildings and the floor systems. Your concrete floor (if present) will conduct through your machine if it is a better ground than the one supplied by the Electrical service.

              If you aren't completely sure, have an electrician check it out and repair your grounding issues. This is not a good situation to be in if you are getting "tingling" or a "buzz" from your machines. A slight increase in your conductivity caused by sweating or a wet floor could be extremely dangerous or deadly.

              Bob

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              • #8
                For a separate building sub-panel the later codes now require BOTH an remote ground rod AND a grounding conductor run between the buildings (there are exclusions and a couple of ways to do this so look it up). Check your local AHJ for what pertains to you.

                For a "local" sub panel, as explained above ground is from your main panel and the neutral is NOT bonded to ground at the sub-panel case.

                Comment


                • #9
                  Ok, here is a pic of the setup.

                  I think I have the 3rd wire (bar aluminum line labeled "main" in pic) going to the wrong spot

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                  • #10
                    Is that a 4 wire incoming feed? I can't tell but it looks like 2+G. You need 2 phase wires, a neutral AND a ground if you are going to derive any 120v loads. You cannot do this is you have only 2 wires +ground, and even if a separate building, you cannot repurpose that ground braids as neutral (both ends) and provide a separate ground. Did you just grab the feeder going to the stove and try to substitute a subpanel?

                    Run a NEW feeder cable - 3W plus G.

                    BTW.. an OVEN (if allowed by your AHJ) can use (grandfathered) a 3 wire circuit even though it's wired for 4 - like yours is (assuming there a ground wire somewhere). You cannot wire a sub-panel like this And.. where is the OVEN GROUND WIRE? If there is no separate ground wire, the "white" is likely assumed to be connected to ground, not neutral... but investigate to make sure it's simply not just cut off.


                    If you use aluminum feeder, you must use antioxidant paste on the wires /terminals, both ends.

                    And.. look at the instruction on the subpanel for the removal of any neutral/ground bonding.
                    Last edited by lakeside53; 10-24-2015, 12:38 PM.

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                    • #11
                      OMG, your panel wiring reminds of the stuff I saw in Mexico.
                      No budget for proper electrical connectors?

                      Is that orange extension cord running out of the bottom of the panel?

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                      • #12
                        Buy yourself some grommets, trim that feed wire up. If 3 wire, If it's 3 wire, black and white go to the main breaker, ground to ground with neutral and ground busses tied together. If 4 wire, black and red to mains, white to neutral, ground to ground and not tied to neutral. Then throw a ground rod in.
                        Last edited by kendall; 10-24-2015, 12:21 PM.

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                        • #13
                          Originally posted by kendall View Post
                          Buy yourself some grommets, trim that feed wire up. If 3 wire, If it's 3 wire, black and white go to the main breaker, ground to ground with neutral and ground busses tied together. If 4 wire, black and red to mains, white to neutral, ground to ground and not tied to neutral. Then throw a ground rod in.
                          No.. He cannot use a 3 wire (2+G) for this configuration (he has both 120v loads and neutral referenced oven), and no separate ground rod is used if in the same building (residential with no separately derived source).

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                          • #14
                            Originally posted by Rosco-P View Post
                            OMG, your panel wiring reminds of the stuff I saw in Mexico.
                            No budget for proper electrical connectors?

                            Is that orange extension cord running out of the bottom of the panel?
                            No..that is not an extension cord. Just the color of the jacket. It's solid wire.

                            As for connectors, I didn't put them up top yet as am not done..and I now think I will have to redo. And this is much better than my main box.

                            Ok, its 3 wire..so that is the first problem.

                            So go 4 wire, run the main ground to ground in sub, neutral to neutral and hots to hots.
                            Last edited by cuemaker; 10-24-2015, 12:36 PM.

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                            • #15
                              Yes.. and investigate how your oven is connected. If it is truly three wire, your white will need to go to panel ground, not neutral. Take care with this... and make sure it's not messed up at the oven end.

                              When you rewire it, put ONLY your ground connection on the ground bar; your 120v neutral connections go only to one of the two neutral bars. Although it's usually the default, make sure the neutral bars are not bonded to ground.


                              What size breaker are you feeding the panel from?
                              Last edited by lakeside53; 10-24-2015, 12:45 PM.

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