Grounding outlets

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  #1  
Old 09-14-05, 06:34 AM
cneff78
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Exclamation Grounding outlets

I have recently bought a home built ~1955. I have a number of outlets that are Open ground and once I pull the outlet to look at it I see NO grounding wire. Each one is housed in a metal outlet box. I had heard that I just need to ground my outlets to the metal wall box but I'm not sure if this is correct or safe.

What should I do?

Thanks in advance
 
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  #2  
Old 09-14-05, 06:50 AM
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You have a code violation. The person who installed the grounded receptacles violated code by doing so, assuming that no GFCI protection is present for these receptacles.

This should have been caught during the home inspection. Either you had no home inspection, or the person who did so did not do a thorough job, or you aren't tell us that you knew about this.. If you had one done and this problem wasn't listed than you should be asking for a refund.

It is certainly safe to connect the ground screw to the metal box, but this may not provide a ground. This will only provide a ground if the box itself is properly grounded, which would only be the case with certain types of wiring.

The proper solution is one of the following:

1) install ungrounded receptacles.
2) properly ground the receptacles.
3) provide GFCI protection.
 
  #3  
Old 09-14-05, 07:35 AM
cneff78
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I did know this via inspection.

I checked the ground of the outlet box via continuity tester and it is grounded but it does not give me as strong a ground indication as the ones I know are grounded.

Is this still adequte to ground an outlet in this manor?
 
  #4  
Old 09-14-05, 07:49 AM
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By "continuity tester", do you mean an ohmmeter function on a multimeter between neutral and ground? If so, then what is the reading in ohms? If not, then what instrument are you using and what two points are you testing between?
 
  #5  
Old 09-14-05, 09:24 AM
cneff78
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I'm using a a continuity tester (50-800v rated device with 2 probes and an indictor light between them) not a multimeter.

I'm probing the hot wire and the metal outlet box itself
 
  #6  
Old 09-14-05, 09:37 AM
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That's not a continuity tester; that's a voltage tester.

But it does sound like your metal boxes are grounded, although perhaps not very well, and perhaps not legally. It's difficult to take this analysis further without better test equipment.
 
  #7  
Old 09-14-05, 09:52 AM
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The essentail question is this--- does the Wiring Method that inter-connects the individual outlet-boxes provide an Equiptment Grounding Conductor (EGC)for Grounding individual receptacles?

Metal outlet-boxes suggest that the Wiring Method is Armored Cable, and the metal armor is an approved EGC provided tha the metal cable is securely clamped/connected to the outlet-boxes.

The EGC should provide a lo-resistance path between the outlet location and the "source", which is where the Branch-Circuit connects at the breaker/fuse panel.A valid resistance test/measurement of the EGC using an accurate Ohmmeter requires connecting a #14 "jumper-wire" between the metallic surface of the panel and the "test-point", which is the metal surface of the receptacle outlet-box.The Ohmmeter will indicate the resistance of the EGC between the outlet-box and the panel.

Want to "give it a try"?

Good Luck, & Learn & Enjoy from the Experience!!!!!!!!!!
 
  #8  
Old 09-14-05, 02:27 PM
cneff78
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So is there a reliable and quick way to check to see if I have suficent grounding to protect my electronics (i.e. computer, TV, etc.) without the ohmsmeter?
 
  #9  
Old 09-14-05, 02:58 PM
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Originally Posted by cneff78
So is there a reliable and quick way to check to see if I have suficent grounding to protect my electronics (i.e. computer, TV, etc.) without the ohmsmeter?
No, but a reasonable multimeter (which can measure resistance) can be had for $20 or less.

http://www.lowes.com/lowes/lkn?actio...0-A&lpage=none

Something like that will do the trick. Most home centers and hardware stores have a similar cheap-o multimeter.
 
  #10  
Old 09-14-05, 06:37 PM
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I don't agree, that if there is some continuity or you can measure voltage between hot and ground, that the ground is viable.
Those tests do not indicate how the ground will perform to shunt high speed transients from a TVSS (surge suppressor). The tests will also not indicate how the ground will perform during a ground fault condition (short to ground).
They may help you feel a little better, but they are not definitive.
Several code cycles ago (probably 10), they decided that an armored cable by itself without an internal bonding strip was not a viable ground. Then they required the internal bonding strip in AC cable.
Does the cable connecting to the metal box have an armored jacket? Does it have a bonding strip. Does it seem that the metal cable is securely clamped/connected to the outlet-boxes?
 
  #11  
Old 09-14-05, 06:57 PM
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A suggestion often made for a crude grounding test is to wire a lamp fixture with a 100-watt bulb (the more watts the better) between hot and ground (for testing only!! don't leave it there). A simple $3 porcelain naked-bulb fixture works well. You can then measure the voltage across the two screws on the fixture. If the ground is reasonable, you'll get a reading nearly identical to what you'd measure when the same fixture is connected between hot and neutral.

Of course the above test cannot identify a bootleg ground. But you might get an idea of a bootleg ground by measuring voltage between neutral and ground while the light is connected between hot and ground. If the ground is not bootlegged, you should see some voltage (probably still less than a volt).
 
  #12  
Old 09-16-05, 08:37 AM
noncom
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Proper way to ground

Ok, almost like in the original question, I have a house constructed in 1956, after much rnovation, there are a still a few original runs of 2 wire plastic/cloth? insulated wire with a few ungrounded outlets, I read this and

Originally Posted by racraft
"The proper solution is one of the following:

1) install ungrounded receptacles.
2) properly ground the receptacles.
3) provide GFCI protection."
I will insure that at the very least number one or Probably number 3 will be followed. What I would like to know is how I could go about properly grounding these outlets. I realize the best solution is a new three wire run back to the box, but for some of these, if that is not possbile what is the alternative? Could I run a ground wire from the outlet(s) to a pipe, or other grounding metal? In the book "Wiring Simplified" it seems to suggets that I could (pg143) In some instances i do have a clear run from the ungrounded outlet to a cold water pipe.
 
  #13  
Old 09-16-05, 08:45 AM
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Do not connect a ground wire to a metal pipe or any other location that seems convenient. Connections to a water pipe need to be done at a specific location and the pipe must be properly connected to the electrical system.

The way for you to properly ground these receptacles is to run a ground wire back to the main panel and connect it with the other ground wires.
 
  #14  
Old 09-17-05, 11:00 AM
noncom
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If there were another line (properly grounded) in the room would it be acceptable to extend a ground wire from that outlets ground to the ungrounded outlet? (not directly from the outlet but from a pig tail in the outlet box)
Does that ground wire, either to the other outlet (if that is acceptable) or back to the box need to be encase (in plastic) or can it be a bare wire.
If I swap out an ungrounded outlet with a GFCI, would the outlet still read as unground? (pretty much know the answer {thinking it would read as ungrounded} to this just want to make sure).
 
  #15  
Old 09-17-05, 12:11 PM
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Some people will say that grounding to a properly grounded circuit elsewhere is acceptable, others will not. This is a gray area.

The easiest type of wire to run would be green insulated stranded wire. While you could run a bare wire or a solid green insulated wire, it will be much easier to run stranded wire. It must also match the circuit size, most likely 15 amps, meaning 14 gage wire.

A GFCI receptacle that is not grounded will read as not grounded with a tester. A GFCI receptacle does not provide, care about, or register a ground. A GFCI provides protection by cutting off the hot wire in the event of a mismatch between hot wire and neutral wire current.
 
  #16  
Old 09-17-05, 08:31 PM
noncom
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Final Question, on this subject at least; well for now... Is it an acceptable practice to simply run a spur or incorporate the ungrounded outlet in to the circuit on which the grounded outlet is on. I would have the ungrounded line then "dead end in that box" cap it off, or if it is in the middle of a run, splice the line inside that box on it's way to the next ungrounded outlet.
 
  #17  
Old 09-17-05, 08:44 PM
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Not quite sure what you're asking, but you're not allowed to extend an ungrounded circuit. Code allows you to keep the ungrounded outlets you have now, but you can't add any more.
 
  #18  
Old 09-17-05, 09:19 PM
noncom
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I dont want to extend the ungrounded circuit, I just want to run an additional line (a grounded line) iinto that outlet box. Can I cap off (or splice together) the existing ungrounded line inside the same box as with the new grounded outlet. The ungrounded line would either terminate in that same box (as the new grounded line and the outlet) or continue on to an existing ungrounded outlet. I would love to terminate the ungrounded line altogether, i just cant just yet, and if i dont keep that line up and running I will lose some other outlets that i need for now.
 
  #19  
Old 09-17-05, 09:28 PM
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Yes, you can, if the box has enough room. But why not just install a new box and leave the old ungrounded box alone? I often recommend that for people installing new circuits. Rather than replace the old circuits, leave them there, at least for now, and add new outlets on new circuits somewhere nearby. That way you still have use of the old outlets and also use of the new ones, and you won't overcrowd the boxes or disturb the old wiring. Some time in the future if you want, you can remove the old boxes or remove the old circuit altogether and run a new circuit into the old box.
 
  #20  
Old 09-17-05, 09:50 PM
noncom
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That really is a much better idea (leaving the old box). I just thought of one final, final question. If with an ungrounded outlet, I chose to add a GFCI, and wired that GFCI so as to protect other ungrounded outlets downstream from that one. With the ungrounded outlets downstream from the GFCI (now protected) must I used 2 hole (ungrounded type outlets) or could I use the 3 hole (grounded) outlets and properly label them as GFCI Protected.
Thanks.
 
  #21  
Old 09-17-05, 10:28 PM
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You may use the three-hole receptacles downstream. Label them both GFCI protected and no equipment ground. Such stickers sometimes come with the GFCI and/or are sold at home centers.
 
  #22  
Old 09-18-05, 01:54 PM
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Just remember that a GFCI is NOT a substitute for a proper ground. Certain electronics want and need a proper ground.
 
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