Ungrounded downstream GFCI

[scosta]

Old home has ungrounded GFCI near the sink, trips with the test button, but does not trip with a GFCI tester, I know this is normal.(but dont really understand why) My question is on the other side of the sink the outlet is linked to the GFCI but does not have a test button. Power goes off when the test button on the first GFCI is pushed.
How does this protect anyone if you have to push the test button to cut power. I dont get it, make me understand.

Thanks, Steve

[brian winkle]

The gfci will work just fine without the grounding wire. It will sense when there is an imbalance and trip. If you used a wiggy with one probe in the receptacle and touched the other to a continuous water pipe it would trip.

Your tester tries to do the same thing by using the grounding path to shunt some current into, but with no grounding wire no current flows so none can turn up missing.

[brian winkle]

Here is a good explaination in Laymans terms, scroll down to the fourth post. http://forums.jlconline.com/forums/s...ad.php?t=35284

[scosta]

Thanks Brian, that was so simply explained, I got it.
Steve

[cbrands]

alot of testers use a ground fault to test.
no ground to fault to...no trip.

[David A. Andersen]

My understanding is a GFCI device (new version) will trip if there is no ground attached. You must become the ground for the device to work.

Put your hand in a sink full of water and put your finger in the small plughole! ("Here's your sign")

I don't think I'll try this one on a routine basis!

[Paul W. Abernathy]

Awww...come on David. We have to have SOMEONE test that theory...lol

[Doug Edwards, CMI]

So simple a caveman could do it.

[Paul W. Abernathy]

lol...I love those commericals Doug...

[Ian Gills]

Hmmmmmm, so by extension my AC with no ground wire but a bonding strip, with self-grounding GFCIs is well grounded since pushing the test button does trip them. Surely this is a test for if older BX with no bonding strip has an adequate grounding path through the metal outer?

Any takers? Should create some shouting.

[Paul W. Abernathy]

lol....no debate here......Older BX has no bonding strip and the internal testing feture of the GFCI also does not need the " bonding " path....but alas don't confuse the use of a GFCI to take the place of a properly installed EGC.

No shouting here......I have been ALL over the country and I hear all kinds of thoughts......I am just here to educate as I will leave the shouting to the ones who feel threatened...

P.S. you should not EXTEND an AC system from a cable that has no EGC to one that does.....the GFCI is a good safety enhancement for a (2) wire system that has no EGC.....not to replace the concept...

[Ian Gills]

I thought the bonding path ensured a good ground. If GFCIs need a good ground to test trip, then surely a ground path is good with or without the strip, if the test trips.

Who needs a ground tester, when a GFCI could do the job, albeit for a little more labor?

[Paul W. Abernathy]

Ahh...terminology thing going on here.....

1.) The call the EGC a " Equipment Grounding Conductor" but in reality it is a " Equipment Bonding Conductor" and it provides a low impedence path for aid in clearing a breaker....(edit: or fuse for that matter...

2.) The GFCI does not need a " Good Ground" to function as it has been explained on here many times how a GFCI functions and the EGC of a system plays no effect on how it functions.

The TEST that trips is in relation to the Ungrounded and Grounded conductors and not the " GROUNDING" conductor which is why some GFCI testers wont trip it....but alas you need the " Dummy Testers" to verify reverse polarity ( guess you could also do that with a voltage ticker" but it also tells you other things.....

Still the proper way to test a GFCI is at the device itself.......the testing devices like the GB and Suretest are great for confirmation but can be fooled....so expensive or cheap...worth having.

[Jae Williams]

Originally Posted by dedwards

So simple a caveman could do it.

Let's leave my family out of this, OK?

[Paul W. Abernathy]

lol....is it only me but the one I like the best is the original caveman...the one that is on the conveyor belt and in the original commericals...I don't like the one they use in that therapist one......sorry....I just had to say that.