Warning

[mike31154]

GFI device will trip without having a ground as well. That's the whole premise behind it actually protecting us from shock. If you contact the hot lead of a GFI protected circuit & sufficient current leaks through your body to an external ground, like a wet floor, it will trip since some current is going through your body instead of back through the neutral wire. The GFI current threshold is so low that it will trip the circuit before the current through your body is enough to be harmful. This will happen whether there is a ground prong present on the electrical receptacle or not. It's also why it's acceptable (even advisable for personal protection) to replace an old two prong receptacle in older circuits using no ground wire with a 3 prong GFI receptacle. The ground prong in this case is not connected to anything, but the GFI can still protect you by sensing a current leak through you to another grounded surface. Hope that makes sense.

[banditpowdercoat]

Originally Posted by mike31154

GFI device will trip without having a ground as well. That's the whole premise behind it actually protecting us from shock. If you contact the hot lead of a GFI protected circuit & sufficient current leaks through your body to an external ground, like a wet floor, it will trip since some current is going through your body instead of back through the neutral wire. The GFI current threshold is so low that it will trip the circuit before the current through your body is enough to be harmful. This will happen whether there is a ground prong present on the electrical receptacle or not. It's also why it's acceptable (even advisable for personal protection) to replace an old two prong receptacle in older circuits using no ground wire with a 3 prong GFI receptacle. The ground prong in this case is not connected to anything, but the GFI can still protect you by sensing a current leak through you to another grounded surface. Hope that makes sense.

Dude, read what you just posted. When current goes through YOU to ground. Where is it going to?? The GFI does not know how the current is getting to ground. ie your tank, you, animals etc. But it IS going to ground. Thats how a GFI works. It detects an imbalance between the Hot and Neutral There is only 3 paths in your household system. Hot, Neutral and Ground. If current isnt flowing back on the N, then it MUST be going back through ground.
GFI's only trip on current leaking, or passing to Ground. Not the GI's ground plug, but ground anywhere. Ground is Ground, common point electrically throughout the house and, yup, you guessed it, the ground outside too

[cwatkins]

This thread just reminded me that the outlet I use for my water change tub (pump/heater) still needs a GFI. I'll pick one up before the next water change.

I was wavering because I wasn't sure if GFI protected devices needed the third ground wire. But since ground is ground, and I now know that leaking voltage can ground through you (as per above), then I'll for sure pick one up now!

[mike31154]

Originally Posted by banditpowdercoat

Dude, read what you just posted. When current goes through YOU to ground. Where is it going to?? The GFI does not know how the current is getting to ground. ie your tank, you, animals etc. But it IS going to ground. Thats how a GFI works. It detects an imbalance between the Hot and Neutral There is only 3 paths in your household system. Hot, Neutral and Ground. If current isnt flowing back on the N, then it MUST be going back through ground.
GFI's only trip on current leaking, or passing to Ground. Not the GI's ground plug, but ground anywhere. Ground is Ground, common point electrically throughout the house and, yup, you guessed it, the ground outside too

I know what I posted & I know ground is ground, a common reference. The point I'm trying to make is, the GFI will work to protect you from getting shocked without the GFI itself needing the ground prong built into it.