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Old 04-27-2007, 11:30 AM   #1
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Suspect grounding in rental home?


I'm preparing to move into a home I've rented and have found that some (okay, most) of the wiring has issues.

The home has a mix of two- and three-prong outlets. Only a minority of the three-prong outlets show ~120V from hot to ground when tested with a multimeter. Most of them show ~12-18V from hot to ground. They all read as expected from hot to neutral, ~120V. (Actually a little higher, ~124V.)

An outlet currently used for the washing machine is among the outlets with a low hot-to-ground reading. If I check from hot to a nearby water pipe, I get ~120V.

As a second issue, one of the outlets in the master bedroom is showing voltage from neutral to ground. Forget the exact reading but it was ~16V. It also has low hot to ground.

Could someone with more experience elaborate on the safety and fire hazards these readings could indicate?

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Old 04-27-2007, 04:20 PM   #2
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Suspect grounding in rental home?


There is no real fire danger, just someone went in and installed 3-prong receptacles where no ground was present.

Tell the landlord/owner. DO NOT attempt to do ANYTHING about this yourself.

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Old 04-27-2007, 05:04 PM   #3
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Suspect grounding in rental home?


I thought that might be the issue, but if it were, wouldn't I see ~0V from hot to ground?

I've notified the owner's agent, who is going to have an electrician take a look at things next week.
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Old 04-27-2007, 05:34 PM   #4
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Suspect grounding in rental home?


Quote:
Originally Posted by Beren View Post
I thought that might be the issue, but if it were, wouldn't I see ~0V from hot to ground?
No, not at all. There are several factors that would give you erroneous readings, especially using a digital multi-meter.
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Old 04-27-2007, 11:42 PM   #5
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Suspect grounding in rental home?


Interesting. As time allows, would you elaborate? I'm going to let the professionals handle this, but I'm curious what would cause misleading readings with the digital multimeter.
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Old 04-28-2007, 06:28 AM   #6
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Suspect grounding in rental home?


Beren, here is a good place to start.

http://www.allaboutcircuits.com/vol_1/index.html
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Old 04-28-2007, 06:50 AM   #7
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Suspect grounding in rental home?


Here's another:
http://en.wikipedia.org/wiki/Phantom_voltage
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Old 04-28-2007, 10:52 AM   #8
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Suspect grounding in rental home?


Aha! Thanks for the links. So if I put a lamp somewhere on that circuit and retest at another outlet, chances are I'd read ~0V from hot to ground if my original readings were phantom voltage, right?

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Old 04-28-2007, 11:01 AM   #9
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Suspect grounding in rental home?


I know for sure that the test you suggest will work if checking hot to neutral on a dead circut. Sometimes I just use a resistor.

Since the ground is not hooked up to the neutal of the lamp, I am not sure what the results would be. If you try, let us know.

If you hook a test light up to hot and ground, then you would get zero.

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