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Old 28th June 2005, 06:47 PM   #1
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Location: Los Angeles, CA
Default No ground wire in my electrical outlets (USA)....

My house is in Los Angeles, CA . Iwas replacing the outlets in my living room and noticed that there are only two wires(live, neutral) in my outlets. There is no ground wire and there are no copper pipes close by to ground to. In fact, the entire house is wired this way.

Is this normal? Is the neutral wire considered ground in this situation?

I picked up some 1.0-2.4kV isolation transformers to use as a result of installing flourescents bulbs and dimmers throughout the house, but I need to be able to connect to the house's primary ground.

Any suggestions on how to best handle this according to proper electrical codes?
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Old 28th June 2005, 06:54 PM   #2
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From http://www.improvenet.com/adviceandr...al.html#ground


I have an old house with only two wires coming to each outlet and switch, and no ground. Can I ground this system?

Yes, in one of several ways. The simplest method is to add a ground fault circuit interrupter (GFCI) at the beginning of each circuit. Find the first receptacle in the circuit (the one first in line from the breaker or fuse panel) and hook it to the "line" side of the GFCI. Then connect the wire going to the remaining outlets on that circuit to the "load" side of the device. Now you can replace all the remaining outlets on that circuit with regular three-prong grounded outlets. These work well for all outlets except for major appliances like refrigerators.

If you have metal armored cable that contains the wires to the box, you can install three-prong receptacles and ground them in the following manner. First, with the power disconnected, replace the two-prong outlets with three-prong. Connect a green jumper wire (which you can buy with a screw already mounted in it at hardware stores) from the green grounding nut on the new receptacle to the box. Screw the jumper wire into the 10/32 threaded hole in the box. Make sure the armored cable is firmly attached by a metal clamp inside the box. If the box has no threaded hole, you will have to drill a hole only slightly smaller than the screw and drive the screw in tight.

If the wires are not in armored cable, you cannot ground them according to code. Use the GFCI as detailed above.
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Old 28th June 2005, 07:34 PM   #3
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Thanks Leadbelly,

My outlet box looked aluminum, but I just drilled a small hole in it and connected a wire, then used a 1.5V batttery to see if I could make a circuit via the box and it did conduct/complete the circuit.

As to whether that leads back to ground, I don't know.

Is there a way to check?
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Old 28th June 2005, 08:00 PM   #4
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Quote:
Originally posted by darkmoebius
As to whether that leads back to ground, I don't know.

Is there a way to check?
Put your meter on AC. If you read 120VAC between Hot and the box, 120VAC between Hot and Neutral, and 0VAC between Neutral and the box, you are sitting pretty.
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Old 28th June 2005, 08:51 PM   #5
sam9 is offline sam9  United States
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A caution for DIYers regarding GFCI. My work area was added (by the previous owner) after my house was build. It was wired with GFCI outlets, but the using only hot and nuetral wires -- no ground connection despite the three prong plugs. I asked about this and was assured by a licensed electrician and a building inspector that it met code as the GFCI alone (without ground) was sufficiently safe.

OK . . .

Then when building one of my first amplifiers I mad a mistake in contruction such that when I sealed the enclosure the mounting bolt through the toroid came in contact with the enclosure top creating an inductive short. However, since the enclosure sat on a wood table and was not earth-grounded the amp appeared to work fine. But when taken to another location in the house the fuse would would pop right away when power was switched on. This was very mysterious to me and masny fuses were consumed while I figured it out.

The amp may have been "safe" when sitting in the work area thanks to the GFCI, but I keep thinking that the path to ground that could trigger the GFCI was ME Not cool!

Setting aside the safety issue, testing the amp with out a true earth ground sets up the possability that a serious construction error can be present but not detected. So I recomment that at least for your work area try to find a way to get a true earth ground installed, not just a GFCI.

& BTW -- in the absence of an earth ground your oscilloscope is floating. Again the GFCI may make this safe but there may be other problems that result
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Old 28th June 2005, 10:30 PM   #6
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Quote:
Originally posted by leadbelly
Put your meter on AC. If you read 120VAC between Hot and the box, 120VAC between Hot and Neutral, and 0VAC between Neutral and the box, you are sitting pretty.
I'm a very happy camper Thanks, Leadbelly.

Oddly, hooked up an 1.0kV Elgar isolation transfomer according to their instructions and it actually caused my 7 wpc SET monoblock amps to noticeably buzz.

I wired them up 2 different ways and had the same effect:

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