Open Ground Wall Outlet

Posted on 2005-04-07
Last Modified: 2011-08-18
I recently tested all the outlets in my house. They are 3 prong outlets but they all have an "open-ground". I have all my computer equipment pluged into these outlets. What is the danger or disadvantage of having  open-ground wall outlets. What could be the negative effects of having open-gournd outlets.
Question by:jtwoods4
    LVL 14

    Expert Comment

    Subject: How do I convert two prong receptacles to three prong?

          Older homes frequently have two-prong receptacles instead
          of the more modern three.  These receptacles have no safety
          ground, and the cabling usually has no ground wire.  Neither
          the NEC or CEC permits installing new 2 prong receptacles anymore.

          There are several different approaches to solving this:
              1) If the wiring is done through conduit or BX, and the
                 conduit is continuous back to the panel, you can connect
                 the third prong of a new receptacle to the receptacle
                 box.  NEC mainly - CEC frowns on this practice.
              2) If there is a metallic cold water pipe going nearby, and
                 it's electrically continuous to the main house ground
                 point, you can run a conductor to it from the third
                 prong.  You MUST NOT assume that the pipe is continuous,
                 unless you can visually check the entire length and/or
                 test it.  Testing grounds is tricky - see "Testing
                 Grounds" section.
              3) Run a ground conductor back to the main panel.
              4) Easiest: install a GFCI receptacle.  The ground lug
                 should not be connected to anything, but the GFCI
                 protection itself will serve instead.  The GFCI
                 will also protect downstream (possibly also two prong
                 outlets).  If you do this to protect downstream outlets,
                 the grounds must not be connected together.  Since it
                 wouldn't be connected to a real ground, a wiring fault
                 could energize the cases of 3 prong devices connected
                 to other outlets.  Be sure, though, that there aren't
                 indirect ground plug connections, such as via the sheath
                 on BX cable.

          The CEC permits you to replace a two prong receptacle with a three
          prong if you fill the U ground with a non-conducting goop.
          Like caulking compound.  This is not permitted in the NEC.

          The NEC requires that three prong receptacles without ground
          that are protected by GFCI must be labelled as such.

          Examine a receptacle, sounds like you are not within code.
    The greatest hazard is not to the equipment but to the operator.

    Author Comment

    My question was not how to wire a 2 prong outlet to make it have a gournd connection. Let me restate the question.

    They are 3 prong outlets but they all have an "open-ground". What is the danger or disadvantage of having  open-ground wall outlets. What could be the negative effects of having open-gournd outlets.

    Author Comment

    SPECFIFCALLY, What is the danger to my equipment. What can happend to my equipment if there is an open ground?
    LVL 6

    Expert Comment

    How old is your house? Surge protectors do not have a chance of working with an "open ground".
    LVL 6

    Expert Comment

    If your house was wired for the grounded outlets and the wires were just connected wrong the ground would show as open or unprotected on a surge protector when you plug it in.

    Author Comment

    Yes, it shows as open on the surge protector.
    LVL 8

    Accepted Solution

    OK, i fyour have an open circut, then you dont have any ground protection, this will make your Supressor useless as it will only protect your system if it can direct the current to travel somewhere else. If you need ground, and your outlet doesnt offer true ground, get a "continuous" battery backup, then the computer is off of the house power grid, and is literally run off of a battery with some circutry between the two, any spikes or fluctuations will be absorbed unless it is an insanely large spike, then the battery and likely the system will just be murdered. For more info, go here...
    LVL 6

    Assisted Solution

    You still need to answer how old the house is, the three prong outlets should be wired with three wires. Did somebody just install new three prong outlets on a two wire house wiring system? If that is the case it can not be up to code or safe. Shut off the power and pull one of the outlets out of the wall to see how many wires you have. Also check the main breaker box to see if the ground wire is connected if you do find three wires. It could be as simple as switching the black and white wires if you have three wires just to make the surge protector happy.

    Author Comment

    I rent so I am not sure how old the house is. I will take a look at my wiring and see what it looks like.
    LVL 6

    Expert Comment

    I think you should notify your landlord, as this no ground should not be up to rental code. Check with your city rental building inspector if the landlord will not listen to you. I would not suggest you playing with the wiring in a rental property unless the landlord approved of it.
    Thanks for the points,

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