+ Reply to Thread
Results 1 to 9 of 9
  1. #1
    Join Date
    Jun 2009
    Posts
    1

    Default Two Prong Outlets in A Three Prong World

    Hello All.

    I recently moved into an old house built in 1925 that has a mix of old and new wiring in it. The bathrooms and kitchen have all had their wiring updated along with a few other outlets here and there. However the rest of the house is two wire outlets. In the living room I need a grounded outlet for my TV stereo etc, but there is only a two prong outlet there. I know they make 3-2 prong outlets with a screw adapter that you can buy. IF I get one of these and IF I test it with a multimeter/outlet tool that says it is properly wired is it safe to use on my electronic equipment? I have measured the voltage between hot and the plate screw and it is as expected ~120 volts. Does this imply that the box is properly grounded through metal conduit? Some of the outlets do not measure correctly, but the one I want my TV plugged into does. Is a 3->2 adapter OK in this situation? Or is the only alternative getting an electrician out here to fix it?

    Also, when testing the other outlets in the house some of the new three prong outlets indicate that they are not properly grounded as well. I have alerted my landlord of this issue, but he doesn't seem to excited about getting an electrician out here and fixing them. If these outlets aren't in use do they pose a hazard? Can they be safely used as a two prong outlet? I measured the difference between Hot and Ground and got in the 20-40 volt range. Does this indicate simply a disconnected ground? Or some other wiring problem?

    Sorry for so many questions... Being a renter after being a home owner is extremely frustrating. I wish I could get an electrician and have the wiring fixed as it should be.

  2. #2
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,622

    Default Re: Two Prong Outlets in A Three Prong World

    As I see it, as a renter you have 2 choices 1] live with it 2] call the building department and file a complaint. Option one your land lord is happy and you get to stay option 2 the building dept could condemn until electrical is bought up to code in which case you would have to move and never likely to rent from this land lord again.

    Grounding an outlet provides very little in personal safety. Installing a GFCI receptacle whether grounded or not provides the max in personal safety.

    If you absolutely need a ground for filtering then running a ground wire to the outlet would be the way to go, I would not depend on conduit in and old house as a good ground.

    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  3. #3
    Join Date
    Apr 2009
    Posts
    19

    Default Re: Two Prong Outlets in A Three Prong World

    If the hot to plate screw gives you 120 volts, then the plate screw must be grounded. I would feel safe using a 3 to 2 adapter with a grounding screw that attaches to the plate. Is it through conduit, through armored cable, or just connected to a three wire piece of cable going back to the box? Doesn't matter, so long as it is there.

    Re: other, less well-grounded outlets... as far as I know, there is no way to compel a landlord to fix this. If you do make a stink , usually you'll find that what will happen is that -after you move- the landlord will not be able to re-rent until the violation is fixed.

    But you should also know that this 'safety ground' is a redundant return to the electrical service box, in place just in case something (what?) happens to the white 'return' wire. Current flows between the black and white wires, and the saftey ground only comes into play when there is a problem with the return wire.

    There are any number of dire situations wherein something -could- happen to the wiring in your home or in some electrical product. To my knowledge, nothing like that has ever happened to me in my entire life, and I have been working with electrical devices and electricity since I was 12, and I'm about to retire.

    The point being; yes, the saftey ground is important and has value. But if it was really a dire issue, three wire retrofitting of all electrical outlets would be a REQUIREMENT. It is not. Use your electrical gear in peace.

  4. #4
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,622

    Default Re: Two Prong Outlets in A Three Prong World

    The ground wire is not a return if something happens to the white wire. It is to provide a current path if the Hot wire should be shorted to the case of the equipment and cause the breaker to trip, however for some electronic equipment it is also a path for noise filtering and provides a reference voltage for digital ground so separate units can be connected without damage caused by floating power supplies.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  5. #5
    Join Date
    Apr 2009
    Posts
    19

    Default Re: Two Prong Outlets in A Three Prong World

    The ground wire and the white wire are bonded together in your service box at the grounding bar/s, making a single connection. Their path from that point on back to the transformer is through a single wire. Their path to your outlet is through parallel wires. The ground wire will serve the same function as the white, because it is connected to the same point in your service box and does not go through any other circuitry between that point and your outlets.

    If you meter the ground wire, it is often carrying voltage (though technically it shouldn't).

    The safety portion of the saftey ground is indeed to provide another path to ground besides your body if you should come into contact with a 'hot' piece of gear, be it via the chassis or whatever. Though not much electrical gear today has metal chassis. We have to respect electricity, it can kill us. None of this has very much to do with being able to use 2 prong outlets without fearing the outcome. But understanding how they work may help the OP to feel more comfortable.

  6. #6
    Join Date
    Feb 2009
    Posts
    693

    Default Re: Two Prong Outlets in A Three Prong World

    Quote Originally Posted by JLMCDANIEL View Post
    As I see it, as a renter you have 2 choices 1] live with it 2] call the building department and file a complaint. Option one your land lord is happy and you get to stay option 2 the building dept could condemn until electrical is bought up to code in which case you would have to move and never likely to rent from this land lord again.

    Grounding an outlet provides very little in personal safety. Installing a GFCI receptacle whether grounded or not provides the max in personal safety.

    If you absolutely need a ground for filtering then running a ground wire to the outlet would be the way to go, I would not depend on conduit in and old house as a good ground.

    Jack
    I’d be really careful here. Most municipalities do not have codes requiring that current code levels are required for existing installations.

    Second is that unless you can make a new grounded system installed correctly, you will need to comply with hundreds of current code requirements and understand them. To install a ground wire from each receptacle and tying it to some arbitrary “ground” or ground rod would be more dangerous than leaving the system as is. A “ground” needs to be thought of as an alternate return to the neutral and not a path to “dirt”.

  7. #7
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,622

    Default Re: Two Prong Outlets in A Three Prong World

    Quote Originally Posted by NEC View Post
    I’d be really careful here. Most municipalities do not have codes requiring that current code levels are required for existing installations.

    Second is that unless you can make a new grounded system installed correctly, you will need to comply with hundreds of current code requirements and understand them. To install a ground wire from each receptacle and tying it to some arbitrary “ground” or ground rod would be more dangerous than leaving the system as is. A “ground” needs to be thought of as an alternate return to the neutral and not a path to “dirt”.
    You are correct, option 2 would only have affect if the electricity is disconnected during non occupancy.

    Yes, but running a wire from the outlet to the ground/neutral buss at the panel does meet code and is allowable to meet bonding requirements. And some electronic equipment needs the bonded connection for noise filtering to work and as the reference level for power supplies. A connection to "dirt" is the grounding electrode and has to do with lightening protection only.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  8. #8
    Join Date
    Dec 2007
    Location
    MN
    Posts
    455

    Default Re: Two Prong Outlets in A Three Prong World

    Don't surge supressors also need a grounded outlet to function properly?

  9. #9
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,622

    Default Re: Two Prong Outlets in A Three Prong World

    Quote Originally Posted by bsum1 View Post
    Don't surge supressors also need a grounded outlet to function properly?
    Yes and no, some just have MOVs across the line to clamp voltages over 130 V others have MOVs and filter circuits from line to ground so it depends on which type you get.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •