Two Prong to Three Prong Outlets and Grounding

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Old 03-18-13, 02:07 PM
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Two Prong to Three Prong Outlets and Grounding

I recently had my electric service upgraded from 60 amps to 200 amps. The electrician also grounded the system, two long metal rods were dug into the ground, and something was connected to water intake pipe to the house as well as a connection made between the pipes on the hot water heater. The electrician also installed a surge protector.

The house was built in the 1950s. The kitchen and bathroom outlets are GFIs. All of the other outlets are 2 prong outlets. I want to install three prong outlets. I have seen where sometimes a grounding wire is attached to an outlet and then the grounding wire is attached to the metal box housing the outlet.

Since the system is otherwise grounded, do I still need to add the grounding wires to the outlets? Or can I just replace all of the two prong outlets with three prong outlets without any additional grounding?
Thank you for your advice.
 
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Old 03-18-13, 02:11 PM
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You have a grounding system in place for the panel now. You would need a ground wire from each receptacle to the panel to ground them (and hence be able to install three prong receptacles). Do you have that?
 
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Old 03-18-13, 02:26 PM
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Grounding to the metal box would be ineffective since the box itself is not grounded.
 
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Old 03-18-13, 02:28 PM
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I do not believe that I have a ground wire from each receptacle to the panel. And I think the wiring from the panels to the receptacles are only 2-wire, not 3-wire. Is there any way to get the outlets grounded without installing new 3 wire wiring?
 
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Old 03-18-13, 02:31 PM
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Just so I understand, what was the point/advantage of only grounding the panel? Does that still help with an electrical surge? Was that the point of having it done?

The cost/time of rewiring the entire house is a little beyond my means right now.
 
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Old 03-18-13, 02:33 PM
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Not sure if it's the same in NJ as NYC and other places...but do you have regular cable or is it in flex conduit?

You can also use a GFCI as the first receptacle on each run and you will get the safety (more actually) of a grounded receptacle all the way til the end....but it won't give any sort of equipment protection.

Oh...it may be possible to ground to the water system somehow. Do you have a basement with exposed plumbing? I asked about this once because my FIL did it in his old place...and basically, I was told...if done correctly it was safe. Don't remember if it was LEGAL though.

Pro's can clarify if I'm in error here.
 
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Old 03-18-13, 02:34 PM
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Grounding the panel is for high voltage event like surges and lightning.

Grounding a receptacle is to provide a means to trip a breaker should a fault occur.

Two distinctly different purposes.
 
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Old 03-18-13, 03:50 PM
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it may be possible to ground to the water system somehow. Don't remember if it was LEGAL though.

Pro's can clarify if I'm in error here.
You can add a branch equipment conductor as a separate pull if you take it back to the bonded ground in the panel or to the EGC within 5' of the panel. The bonding conductor between the cold water inlet and the panel is part of the GEC.
 
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Old 03-18-13, 05:15 PM
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The basement does have exposed plumbing and there is a connection that was made to a pipe for grounding. But that doesn't ground the outlets, right?

So, aside from using a GFCI as the first receptacle on each run, I would have to rewire the whole house to include a ground wire? If I go the GFCI, and it does not provide any sort of equipment protection, what is the point of doing it?

Thank you for your advice.
 
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Old 03-18-13, 05:42 PM
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The basement does have exposed plumbing and there is a connection that was made to a pipe for grounding. But that doesn't ground the outlets, right?
Right. That bond is part of your Grounding Electrode Conductor (your GEC). That protects your service against high-voltage transients such a lightening and transmission surges.

So, aside from using a GFCI as the first receptacle on each run, I would have to rewire the whole house to include a ground wire? If I go the GFCI, and it does not provide any sort of equipment protection, what is the point of doing it?
The point of the Equipment Grounding Conductor )the EGC) is not to protect the equipment. It has been added to wiring systems to protect us from electrical shock. It's there to provide "a low-resistance path to ground" for any live potential that finds its way onto the parts of hair dryers or radios or lamps or clocks, so that that power doesn't find a path to ground through our bodies when we touch the appliance that has a fault.

GFCI protection does that too, and arguably does it better. That's why the NEC specifically allows 3-slot receptacles to be installed on 2-conductor wiring iff that wiring has GFCI protection.
 
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Old 03-18-13, 08:22 PM
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Adding the GFI allows the use of 3 prong devices on a 2 wire ungrounded system.
 
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