Grounded outlets

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  #1  
Old 08-09-13, 06:56 PM
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Grounded outlets

I just purchased a house built in 1955. At some point a previous owner had a circuit breaker installed and there is a ground wire coming from it (connects to a pipe I believe). Someone also replaced a few of the two-pronged outlets with 3 prongs but I do not think that these are truly grounded. When I use a multimeter I get no current checking the hot and ground plugs.

Are these outlets still grounded? What purpose does the grounding wire serve from the box, and how can I add ground to the plugs to protect electronics?

Thanks for the help!
 
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Old 08-09-13, 07:12 PM
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Sure hope that's a typo.
If a ground wire was connected to a breaker it would be a dead short.
Got a picture inside the outlet box and of the panel box?
Is there steel flexible conduit coming to the inside of the outlet box?
 
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Old 08-09-13, 07:27 PM
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I am not at the house now - and I am probably not accurately describing what I saw. The home inspector pointed out the ground wire to me and made it sound like a good thing, but I'm not sure what else it would be connected to.

There are two steel flexible cables coming out of the breaker box but I can't tell if these run to the outlets. Also, using the multimeter I get no current testing the hot plug and the middle screw holding the plate in.
 
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Old 08-09-13, 09:32 PM
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Welcome to the forums.

You would need to check for voltage between the smaller slot in the receptacle to the plate screw.

There should be more than two steel cables coming out of the panel. Basically you need one cable per circuit. If your house uses steel cable (BX) then you should find ground at the box.

Do you have a circuit breaker panel or fuse box ??
 
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Old 08-10-13, 12:33 AM
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I have checked the voltage using the small slot and plate screw, and it shows no voltage. The house has a circuit breaker box and as I recall there are two steel cables coming out of the top.
 
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Old 08-10-13, 04:08 AM
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A picture would help greatly.
 
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Old 08-10-13, 09:00 AM
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Here are some pictures... first is the entire breaker box. The second shows the ground copper wire, and the third is just a closer look at the wires going into/out of the box.

After re-checking all of the outlets, I found only TWO grounded ones. One was a two-prong that showed ground at the metal box so I would just need to add a wire, and one was a three-prong plug that had a newer plastic box (no idea when it would have been installed).
 
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Old 08-10-13, 09:18 AM
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Nice pictures.

Looking at the wiring it would appear that most of your circuits leaving the panel are grounded. Any cable with plastic jacket should have it's own ground. Cloth covered wiring is questionable. BX is grounded by it's jacket but it relies on the connection between the metal jacket and the box. If the clamp is loose in the box you will lose the ground at that point.
 
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Old 08-10-13, 09:52 AM
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But what is this A/C cable? No neutral but hooked to a breaker. Almost looks like an armored ground wire.

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It appears to cross over the neutral bar and into the breaker.

At some point a previous owner had a circuit breaker installed and there is a ground wire coming from it
 
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Old 08-10-13, 10:16 AM
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Without a larger picture I would say that looks like someone taped up a bare ground. The alignment does not look quite right to be on the breaker. Why they went so far down the bus I don't know.
 
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Old 08-10-13, 10:25 AM
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I thought that was a baby ground into the terminal block. Maybe a picture of that side of the box would help.
 
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Old 08-10-13, 11:08 AM
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Just weird but it sure looks like BAG (bare armoured ground) that's been taped and it definitely is on top of the neutral bar not in it.. Almost seems to go under not into the breaker though.

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Old 08-10-13, 04:24 PM
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The AC breaker is actually on the left side, not the right - I had the seller correct the size because it was on a 40 amp breaker and the unit should have been on a 20.

So, if the circuits are grounded at the box, does that provide some form of protection? Re-wiring the whole house isn't an option for us. Can we use ungrounded plugs and fixtures without burning the place down?
 
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Old 08-10-13, 07:13 PM
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So, if the circuits are grounded at the box, does that provide some form of protection? Re-wiring the whole house isn't an option for us.
A branch can't be just "grounded at the box." It either provides grounding by having an equipment grounding conductor - an EGC - or it doesn't.

Your service can be and should be grounded, by having a robust grounding electrode conductor - a GEC - made up in the box, or enclosure, where your main overcurrent protection device is mounted.

Can we use ungrounded plugs and fixtures without burning the place down?
First, terminology: A plug is the thing with 2 or 3 prongs on the end of a cord. The device that you plug it into is a receptacle.

Can you use ungrounded receptacles without increasing your risk of fire? Absolutely. Grounding circuits only came into use in the 1960s, which is 70 or 80 years after residential electrical systems were first installed. In addition, the EGC that's run from a panel to the outlets on a branch circuit is, as its name implies, an equipment grounding system. It was designed and implemented to protect people from shock.

Until you have an EGC on a circuit, all of the receptacles on that circuit need to be 2-slot ungrounded devices, unless you install a GFCI receptacle as the first device in the circuit and use it to protect all of the other devices down the line. Then you can safely install and use 3-slot receptacles without an EGC to connect to them.

The grounding electrode that's created where your electrical service enters your house, OTOH, Is made to shunt high voltage transients such a lightening away from your household wiring. That's a first line of defense against fire.
 
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Old 08-11-13, 11:34 AM
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What I decided to do was install GFCI breakers on the circuits that I will be using for equipment. I know it doesn't provide protection for the equipment but it will at least prevent anyone being shocked, and I can replace the two-prong receptacles with 3-prong ones.

One of these breakers is working fine, but the other keeps tripping as soon as it is turned on. There is no load on this one (nothing connected to any outlets). Any idea why this one is giving me trouble? Yes I double and triple checked to make sure I wired everything correctly.
 
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Old 08-11-13, 01:19 PM
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Does it trip if it does not have the black connected?
 
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Old 08-11-13, 01:31 PM
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Just checked that and yes, it does trip if the black wire is disconnected.
 
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Old 08-11-13, 01:53 PM
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Try with both the black and white wire disconnected. If it still trips it is probably a bad breaker.
 
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Old 08-11-13, 02:08 PM
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Did you mean the black and neutral wires? My neutrals are tan rather than white. It stays on with both of those disconnected. Any other suggestions?
 
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Old 08-11-13, 03:22 PM
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No such thing as tan neutral wires. You have discolored white wire. One more test. You said one GFCI breaker worked so try the problem circuit on the known good GFCI breaker.
 
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