Open Ground


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Old 11-26-03, 06:23 AM
Christopherrrrr
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Open Ground

Installing a GFI over the kitchen counter. The ground is hot when I put a tester to it. What does an open ground mean?
 
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Old 11-26-03, 07:19 AM
R
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You have said two different things here. An open ground is not hot. An open ground is simply not connected to anything.

How many wires feed this outlet? Are there two wires, or are there two wires plus a ground? If there are only two wires then the ground should be open. This will not affect the functioning of the gfci in any way, it will still trip if it detects a ground fault. (If there are only two wires then the outlet should be marked "No equipment ground".

If there are three wires then you need to determine why there is no ground. Where was this outlet wired from? Another outlet? The panel? Is the ground properly connected at the previous outlet or at the panel?

One other note, there is a way for there to still be ground with only two wires. Certain types of cable, or wires run in conduit use the conduit or cable itself to provide the ground. In these cases there will only be two wires, with the ground being the cable or conduit.
 
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Old 11-26-03, 08:24 AM
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For the Ground (conductor?) to be "hot" there would have to be a reading of 120 volts between the Grounding conductor and the Grounded conductor (White wire) and/or 120 volts between the Grounding conductor and Grounded metallic surfaces such as water-lines and the metallic surfaces of electrical outlet-boxes , the frames of electrcal appliances,and the enclosures of electrical equiptments.

"What is an open Ground?"---If you were to take voltages readings at a receptacle-outlet ,and read 120 volts Black-to-White and Zero volts Black-to-Ground, that would indicate an "open Ground."

The Grounding conductor (bare wire) essentialy "parallels" the Grounded conductor (White wire) by forming a seperate conductive path for conducting "fault-currents" back to the "source", i.e., the circuit-breaker panel.Because the Grounding Conductor and the Grounded conductor are parallel but separate conductors, there is 120 volts between the Black, Un-grounded conductor and the Grounding/Grounded conductors.

Should the Un-grounded Branch-Circuit conductor (Black wire) make contact with a metallic surface, creating a shock-hazard, the Grounding conductor will conduct a "fault-current" that will "trip"the C-B and open the circuit.

If the metallic frame of an aplliance is not "bonded" to a Grounding conductor, there will be 120 volts between the metal frame and any surface that is considered Ground, creating a shock-hazard.
 
 

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