Stray voltage trips GFCI with ground probe???

[REEFLIFE]

OK, I am just looking for a simple answer. We all read the poll on using GFCI. I am almost conviced to rig something up after 10 years but I have a question and can't find a post that answers it. I use a ground probe (my protection, ect.) As most of you, I always come across a faulty power head or something that leaks stray voltage. Seems like every time I check. I test once a month or so. The one I have today gives off about 5-6 volts (not a rio, only 4 months old). If I install seveal GFCI to split up my equipment: 1. Where should the ground probe plug into (one of the GFCI or the main socket). 2. Will a little stray voltage like 5-10 volts through the ground probe trip one or all of the GFCI? I travel a lot for work and I don't want my GFCI tripping everytime there is small stray voltage. Again, unless I'm just different, there always seems to be small stray voltage 10 volts or less. Many threads on ground probes and GFCI, just need a simple answer to this question.

[Paul B]

The GFI that the faulty device is plugged into should be the only one that trips if it's the only one on that circuit. If all the GFI's are on the same circuit they may all trip or just some of them. I know thats confusing but I install thousands of these things and more than one can trip if it is on the same circuit or even the same phase in the panel. If you have them on different circuits then you would probably be OK and just one would trip.

[REEFLIFE]

Huh, my intent would be to place about 4 GFCI in 4 boxes screwed to a peice board. I have not looked greatly into the wiring but I want all 4 to be seperate but attached to the same power cord that I will plug into my main outlet (non-GFCI). So if I hear you right and my wiring is done the way I intend, even if a device is not shorted and working but dumping a small voltage in the water it will trip that GFCI (at least with a ground probe). Would it matter where I plug the ground probe (either one of the GFCI outlets or the main outlet). This answer is what I was afraid of eventhough no one else seemed to say it was an issue. Even equipment that is not misfunctioning can put out some stray voltage. Even the lights suspended 8" above the tank can somehow cause stray voltage. In fact, I don't have it grounded yet but I have a 3 month old Buske fixture that I know is leaking. If I have my hand in the tank and my arm hits the light I get a zap. I was going to add a ground probe to the fixture since there is no way for me to find out how voltage is moving through the light. This makes me lean to not adding GFCI. I am away from my tank too much and I see to much stray voltage come and go to risk my tank. I may have to rig it so I can plug into GFCI when working on it and in a main when I am not. How does everyone else get around this issue.

[Paul B]

The way you are wiring it if one trips they may all trip. They all have to be connected to a ground also. Stray voltage that is induced into the water from heaters and lights will not trip a GFI. It will only trip if you have a defective device or if you splash a bunch of water on a light socket. I would use one GFI for everything like everyone else does.

[Frick-n-Frags]

And that stray voltage "induced" by anything won't be bled off by a ground probe either because that induced potential is in no way associated with ground.

BTW, how would you measure for induced voltage? Tank end,to tank end? (I'm not sticking my MM probes in the salt, my MM is screwed up enough as it is :D)

You would think that saltwater would really collapse any induced fields because of its high conductivity.

[REEFLIFE]

PaulB, I'm not sure if I follow you. As long as you pigtail them in the right way I read you can have several on the same line but actualy be sepeate. There are supposed to be 2 sets of connections on each plug (can't remember their name) and depening on which ones you use to connect down line will make them seperate or together.

To test for stray voltage, Take out your ground probe. Using a voltage meter, the black lead goes to the round ground socket of your plug and the red lead you put in the tank water. If you have stray voltage it will run into the meter to get to the ground. My one power head is giving off 5 volts. If it were a broken cord or something like that I would think you would get a lot more than that plus a good jolt with your hand in the water. Cant even feel it. With this pump unplugged I get zero.

[Randy Holmes-Farley]

PaulB, I'm not sure if I follow you. As long as you pigtail them in the right way I read you can have several on the same line but actualy be sepeate.

Yes, that can work fine. I've got many individual GFCI on single lines. Only individual ones trip if wired that way.

[REEFLIFE]

Thanks Randy. I thought I read that in the long poll posts. Would you plug your ground probe into the main socket or one of the GFCI (if so, which one). Do you know if any amount of stray voltage is present will it be tripped.

[Paul B]

Randy that is not necessarily true. In the real world where GFI's are used for appliances and other seperate things it is true that only one would trip with a ground fault. But in a tank where all the GFI's are on the same circuit and all are grounded in the same water more than one "may" trip. If a current leak is detected by one GFI through the water it "may" trip another one on the same circuit. Thats "may" not "will".
Anyway that is my expert opinion.

[REEFLIFE]

Well I have it built and when you trip (test) 1 the other 5 stay live. I'm not sure whether your point about all of them may trip is right or wrong. I have done a lot of searching since I am very hesistant to use GFCI. I read many threads of other reefers doing it this way so the whole system does not shut down due to one bad device and it seems to work for them. Time will tell since you can't get a concrete answer.

[REEFKEEPA]

Don't touch anything metal while you're sticking your hands in your tank and you won't need a GFCI. Stick 1 hand in your pocket.
Better yet unplug everything for a couple of seconds while you dig in your tank.

[REEFLIFE]

Well, I realize not to touch any metal, that's not the issue. Also I do "try" to only put one hand in the tank but have been buzzed before using those rule, not shocked, just buzzed. Like I stated before I went 10 years without a GFCI but the facts are I do get stray voltage in my tank which may or may not turn into anything. I also have a 50 lb 6 foot long 1000 watt light hanging 8 inches from my tank and never know of the cable, connectors or wood beams give out. I am going to try the GFCI setup I made and if I keep getting false trips It's gone. If not, I'll be safer and still use the one hand rule anyway.

[REEFKEEPA]

That's why I am saying to turn it off. Even if you have a GFCI you could still be hurt. DO NOT TRUST THEM, THEY COULD BE DEFECTIVE!!!!!:eek1:

[theearthling]

Originally posted by REEFLIFE
OK, 1. Where should the ground probe plug into (one of the GFCI or the main socket).


It doesn't matter. It will work either way. The grounds for your house are probably all tied together at some point anyway.



2. Will a little stray voltage like 5-10 volts through the ground probe trip one or all of the GFCI? I travel a lot for work and I don't want my GFCI tripping everytime there is small stray voltage. Again, unless I'm just different, there always seems to be small stray voltage 10 volts or less. Many threads on ground probes and GFCI, just need a simple answer to this question.

A GFCI works by measuring the current flowing into the system and comparing it to current flowing out of the system. If there is a difference between the two, then some current must be leaking out the system through another path (hopefully the ground probe) and the GFCI will trip. Voltage is a measure of the strength of the electricity, and does not necessarily mean that current is flowing. So, just because there is a potential difference of 5-10 volts between two components of your system does not mean the GFCI will trip. Out of curiosity, between what components did you measure this difference?

[REEFLIFE]

To answer the one thread, I realize GFCI may not be the save all. I just want to minimize as much risk as possible. As far as turning eveything off, that would not be convient. I need the lights to see what I'm doing. I have a wave maker and timers which would all have to be re-set, ect. Safer, yes.

Second questions: I was wrong, I am leaking about 1-2 volts. I have tried the whole plugging/unplugging everything and I continue to have some stray voltage. May be coming from my suspended lights somehow, did not try turning them off. I do use a ground probe so there is a path to ground and was afraid that low of voltage to ground would trip the GFCI. After several days it has not tripped any. Obviously, with the ground probe in the stray voltage is zero (current going to ground). I currently have my probe plugged into the main plug and not one of the GFCI's. I need to do some more work on trying to find my source of stray voltage if it is just one. I actually bought 2 new pumps thinking it was one of them. From what I hear, it sounds like even a small voltage (if you have a ground probe in place) would trip the GFCI. Why has it not tripped mine? There must be a cetain level before they trip.

[theearthling]

Originally posted by REEFLIFE
I am leaking about 1-2 volts.

Voltage is not a thing that can be leaked. Voltage is a measurement of electrical potential, Much like the energy a boulder has sitting at the top of a hill. My question is how are you measuring it? What I mean is where are you sticking your probes? You don't have to worry about differences in potential unless current starts flowing (the boulder starts rolling down the hill). Potential differences exist everywhere...