Posted: 8/21/2008 11:47:01 AM EDT
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I'm buying an older house where they replaced the original sockets with newer ones, but didn't ground them. The inspector found them with a little gadget. I have a multimeter at home, can I use this to find the ungrounded sockets? If so, how? Thanks guys! |
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Its easy. Set the meter to measure AC current. Put one probe in the earth ground (round) hole. Put the other probe in the smaller slotted hole (hot). Your meter should read ~100 to 130 VAC. If it reads close to 0 VAC then either your electric is off or your earth ground is bad/not connected. Disclaimer - I'm a computer engineer, not an electrician. -Foxxz |
But you are indeed correct. To the OP: I seriously doubt than ran new cable with ground to all the outlets in an old house. It's not uncommon in old houses but just be aware it's not nearly as safe as a grounded system. |
+1 you can even use those $4 sperry socket testers that lowes/home depot sell if you don't own a multimeter... for a standard outlet: HOT / GND = LIGHT HOT / COMMON = LIGHT COMMON / GND = NO LIGHT (if it does light, you better check your connections  )
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I thought that would work, but didn't want to try it until I ran it by someone else. I'm too cheap to buy the gizmo when I already have a multimeter. I love that thing!! It has saved my bacon from touching live wires (should have been dead) or determing when to charge up my backup battery. Thanks! |
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Spend the $5 for the basic tester. It is fast, safe and accurate. www.wiebetech.com/images/products/HotPlug_Accessories/Outlet_Polarity_Tester.jpg |
Get the one that test gfci too. |
I don't want to scare the OP away!
The GFCI tester is more like $10  Maybe we can start a collection fund. 
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This This has been on of the best and cheapest tools I have bought when dealing with outlets. You won't regret it. |
+1 inexpensive and accurate. Easy to ground an outlet too. Some pigtails in the same aisle you buy the tester in. |
GFCI receptacles do NOT require a ground to operate. The cheap little tester DOES require a ground to check them. These testers are NOT adequate for checking grounds in older wiring, and neither is a volt meter. The ground must be capable of carrying enough current to trip the breaker quickly (usually at least 2x the breaker rating). There are ground testers available that will check for the actual current the ground can carry. The cheap little testers may be useful for quickly checking new wiring, but that is about it. They do not verify how GOOD the ground connection is, just that a few milliamps flows. |