Shocking find this may save a life

I have mine in the sump. That's where most of my equipement is so I figured that would be the place for it. But anymore, I don't know. I am still trying to figure out voltage.

 

Close enough. when the circuit is closed and completed, the voltage is still there, but now there is current, which is measured in Amperes. ALL voltages are measurable to ground in all circumstances. Voltage IS potential.

Put another way, in a plumbing analogy, voltage is the pump, amperage is the matter flowing, and resistance is opposition to current, or amperage. Resistance is the diameter of the pipes. Thinner they are, less current can flow. The pump can be attached to a capped pipe, and although no water flows, the potential for flow is still there, as soon as the cap is removed.

The three are directly related in ohm's law, which says that:
I=E/R, or
E=IR, or
R=E/I

where I is current in amps,
E is potential in volts, and,
R is resistance in ohms.

 

Bogie was right on when he said "In Saltwater." That means anywhere in the system. Salt water conducts, so the probe would be just as efficient in the DT as it is in the sump. People usually keep it in the sump to keep it out of sight.

 

*clap, clap, clap*
Yes, and for conventional use, meatball may be correct. But like you (PharmrJohn) now understand, that voltage potential in your 110V outlet can be measured as 110V against a 0V ground, or it can be measured as 0V potential versus another hot "110V" wire in the house, or it can be measured as 9,890V of potential versus the big old 10,000 V power lines. So, it needs to be measured from that outlet to somewhere. Conventional measurement to ground is o.k. mostly when referring to the home wiring.

But,...So what happens when lightening hits the ground very near your house. Your typical 0V ground becomes VERY HIGH voltage, much higher than your "110V" line, and your GFI will pop open. But when it does, the convention to ground measurement is out the window, and the voltage and amps will be HUGE, not 110V ;D. We had a bad lightning storm last summer that fried a GFI outlet in our house, but the circuit breaker was fine.

 

Whenever you measure something with a voltmeter, you are just measuring the difference in electrical potential between the two probes. So in your outlet, there is a hot and neutral wire... if you stick your probe on the hot wire, and the other probe on the neutral wire (or any grounded surface for that matter) there will be ~120 volts difference in potential. You won't fry the voltmeter because it uses either an extremely high impedence (over 10000 ohms) circuit, or it uses the field effect... either way, very very minimal current will flow. It's the current that kills people/fish. All you need is .1 amp of AC to send your heart into fibrillation. So anyhoo, electricity is dangerous/crazy stuff.

I know there are people who may disagree with me, but it seems to me that a ground probe would do more harm than good to the fish in a fish tank. However, it will make your GFCI circuit trip when it is supposed to by making the current differential detectable. I don't have one in my tank, but I do have each powerhead/heater on its own GFCI. So that should keep my fish and my self safe... hopefully


bogie.. truce brotha

 

So is just one ground probe OK, or do I need one ground probe plugged into each GFCI unit?

 

I think one should be fine. As long as it provides a path to ground, it will serve to give 'stray voltage' a path out of the tank. If lightning strikes, all bets are off, LOL.
I have two regular outlets in the wall behind my tank, but they are both wired "down stream" from a GFI outlet, so I only use 1 DIY ground probe.

 

I just joined this forum and started looking around more and found this forum and thought I might add my 2 cents. I am an electrician and have done talks on electrical safety for you and your fish at my local freshwater fish club. My best advice on safety is to get and install a gfci breaker to any circuits leading to your fish/tanks. If this is not possible due to having an old breaker box/fuse box, then install a gfci outlet in the wall, if that is not possible because the box in the wall is not easily accessible or not deep enough for the gfci, then you should purchase a gfci extension. A gfci extension is about 3 feet long and has a gfci breaker/switch in the center and comes out with 3 plug slots in it. Another idea for any of you that have multiple tanks, is to put your lights on one breaker, and your equipment on another, that way you only have to shut off one breaker in order to protect your equipment during water changes. If anyone needs help with their electric issues, feel free to pm me.

 

Now I'm confused again--I live in the lighting capital of the world. In a active season we have violent thunder storms daily. We have lighting rods on the roof and a main surge protector on the house. I have still felt the electric current in a bad storm. Now will the ground probe hurt my stuff during a storm? Just a simple yes,no, or maybe would suffice. Please help, I'm really confused--Too much inf.

 

Could you ground out to the copper ground wire that is the main ground to my house?