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Discussion Starter #1
Hi everyone,
I am a homeowner trying to save some money by doing the work myself. I am new to wiring, but I am trying to swap out my two prong electrical outlets with three prong outlets. I have tested the outlets with a voltage meter and I have found that the receptacle boxes on my main floor are grounded, which made it easy to replace with self grounding outlets.
In my basement, however, I am not getting a ground reading when testing the boxes. I looked inside, however, and I saw that they were wired with the three wires, including the ground wire. Just to test the ground I installed a three prong outlet and attached the ground wire to the green screw. But When I tested with the voltage meter I got only a tiny reading (5-15 volts). Everything I read says that I should get 120 volts when testing for ground.
I was going to just install GFCI outlets to be safe, but my receptacle boxes are not deep enough, meaning I would have to replace all the boxes to install the GFCI outlets. I'll do that if I have to, but before I do I want to make sure I'm not doing something wrong. I really don't want to run new ground wires to each box.
My question is, if I have a ground wire included in my electrical wiring, is it possible that the wire doesn't actually act as ground? Has anyone encountered a situation like this or can they provide any advice? Thank you in advance for your help.
 

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Mad Scientist
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If you have a ground wire connected to the box, but you don't get 120V between the hot and ground, then you need to look for the other end of that ground wire. It must be disconnected somewhere else.
 

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Discussion Starter #3
Thank you! How would you go about tracing the wire? Could I just go to the circuit breaker and look there? What would it look like at the circuit breaker if it is properly grounded, and if it is not what would be the easiest way to ground it from there?
 

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Mad Scientist
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Well, I suppose first you'd need to see which circuit breaker controls that circuit. Then if you look at the wires inside your main panel, you can see where the wire from that breaker comes into the panel. In the same cable entering the panel, there should be a white neutral wire, and a bare ground wire. They should each be connected to a terminal bar inside the panel.

You may want to turn off the main breaker before you open up the panel, unless you feel comfortable working near live power. But remember, even with the main breaker off, the big heavy incoming power wires from the meter will still be live. Stay away from them.
 

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Discussion Starter #5
Thanks McSteve! I'll give it a look tonight to see if the ground is not connected to the panel. I should know which wires to check because I have had to shut down power to those circuits for all the rest of this.
 

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Most likely someone extended a circuit that did not have a ground wire with a grounded cable. If you look in all the boxes on the circuit you will probably find the one with the new cable added.
 

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Discussion Starter #7
So you think I should check each box first? And I am looking for one that does not have a ground wire showing? If I find one that does not have the ground wire, do I have any options for fixing it other than running a whole new cable? Thank you!
 

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You could start at the panel. Since the circuit originates there it is possible that it doesn't have a ground at the panel. If that is the case then you need to replace all the cable that does not have the ground wire.
 
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