targaboat
sulphur springs, tx, usa
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Disregard my previous post, I learned something this time. Thanks all.
Fly Boy
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Dusty R
Charlotte Michigan 48813
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Joined: 04/05/2003
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nbounder wrote:I have understood that a GFI works differently. It measures current flow in the black wire and also in the white wire. If they are not identical, it is assumed that somewhere along the line there's a 'leak' and something (like a person) is conducting current to ground. It then shuts the power off. You do not need a ground connection at the GFI. (unless it and the following outlets have a ground pin) In fact, you can buy a GFI outlet without a connection for ground. Some older homes with no ground pin at the outlets are thusly GFI protected.
You need a ground for the test button to work. Other wise there's no place for the stray current to go to create an unbalance.
Dusty
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Hurricaner
Hurricane Utah
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Dusty R wrote:nbounder wrote:I have understood that a GFI works differently. It measures current flow in the black wire and also in the white wire. If they are not identical, it is assumed that somewhere along the line there's a 'leak' and something (like a person) is conducting current to ground. It then shuts the power off. You do not need a ground connection at the GFI. (unless it and the following outlets have a ground pin) In fact, you can buy a GFI outlet without a connection for ground. Some older homes with no ground pin at the outlets are thusly GFI protected.
You need a ground for the test button to work. Other wise there's no place for the stray current to go to create an unbalance.
Dusty Never really thought about that before but I think you might be right. The GFI will work without a ground but I don't see how the test button could function because as you say there is nothing to leak the current to.
Sam & Kari
Hurricane, Utah
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ShapeShifter
Buffalo, NY
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I also suspect a bad ground.
On a side note, there are times where the test button doesn't trip the GFCI, but the GFCI is otherwise fully functional -- because it's the test button that's broken, not the fault detection circuitry!
A good tool to have in any toolbox is an outlet tester. Many people have the little plug-in device with the three lights, and looking at the light pattern it will tell you about various wiring issues -- hot/neutral swapped, open ground, open neutral, etc. But there is another version that has a button on the side of it to test GFCIs. That button does exactly the same thing as the test button on the GFCI itself.
Such a tool is great for testing the outlets downstream of a GFCI, to make sure they are really protected, and that they will trip the GFCI. But they are also useful for testing the GFCI itself -- if the test button doesn't trip it, but the outlet tester does, you know the problem is in the test button. You can then decide if it's worth replacing the mostly-functioning GFCI or not.
Here is one example of such a device:
Electrical outlet tester with GFCI button
And, by the way, such a device will quickly confirm if the ground is open or not.
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Hurricaner
Hurricane Utah
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Just checked here http://www.rhtubs.com/GFCI/GFCI.htm and I see how they do it without the ground. The test button is tied to the neutral before the gfi so it leaks the current to the neutral before the gfi sees it and fools the gfi that there is an actual ground fault. So... no ground is necessary for the GFI test circuit.
Sam
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Gene&Ginny
North Kingstown, RI
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Hurricaner, thanks for that. I never thought how a no ground GFI worked.
Gene and DW Ginny
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iguana07
Ventura, CA. USA
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I want to thank all of you! Unfortunately it was not as simple as I had thought. The ground is fine and the load and line were not reversed it is something down stream that is affecting the GFI. There were wires there we had no idea what they belonged to. I had to have an electrician over this eve. and the problem will be corrected when he returns, he only had a few minutes to spend so he is rewiring the circuit tomorrow.
Again thanks!
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Hurricaner
Hurricane Utah
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iguana07 wrote:I want to thank all of you! Unfortunately it was not as simple as I had thought. The ground is fine and the load and line were not reversed it is something down stream that is affecting the GFI. There were wires there we had no idea what they belonged to. I had to have an electrician over this eve. and the problem will be corrected when he returns, he only had a few minutes to spend so he is rewiring the circuit tomorrow.
Again thanks! If it is something downstream the GFI has to be already tripped or the test button would work.
Sam
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Hurricaner
Hurricane Utah
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deleted, double post.
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