Would you suggest a grounding probe?

[samtheman]

Yes, if the GFCI fails, it may be serious, but the only thing I have objected to, was calling a ground probe a "safety device". It has no known value, but it is not a safety device. Put one or twenty in your tank, but it will not enhance your safety. That is the one and only point I have been trying to make. If a grounding device has other benefits, I don't know what they are.

 

[Avast Marine]

This is not just a willie nellie pulling out ground probes because someone said so thread. I have read every post here very carefully and if you go back you will find that I was gravely against setting up a tank without one. I have thrown out several worst case scenerios and those have been answered by people that are against the use of ground probes. Where are the people who support this issue and why are they not voicing their factual evidence as to why in certain situations a ground probe is a good thing in the tank? From what I have seen so far the facts have been brought to the table by people who are saying do not put these in your tank, and the people who say put them in have brought nothing to the table except for blanket statements that contain no references nor real world experiences.
My ground probe is still in the tank, it is just not plugged in. So if you wouldn't mind Hal, tell me why it is that I should plug it back in?
Yes I have three seperate GFCI's on my tank so I am conceren about both safety and like to have a backup. And guess what.....I opened the 200A panel and wired all three circuits without tuning off the power. They probably told you not to do that in your first year EE courses too huh?

 

[Runner]

I've been poking fun at samtheman for saying that because I didn't think it really applied to the argument.

What you say is true, Ursus. It matters not whether your GFCI fails with or without a ground probe -- you can still die. Chances are that a non-GFCI breaker will not trip in our situations with just ground probe or just your hand sticking in the tank until there is practically a fire coming up from under the tank...

A ground probe on a tank with bad equipment and a failed GFCI will cook your tank but perhaps stop you from sticking your hand in because the current flow will eventually melt that heater or pump and make a nice cloud of black smoke. And it does, admittedly, make most of the current go down the ground probe. Incremental safety...

 

[Ursus]

Ok so we can agree that using the statement about a failing GCFI in any scenario is a moot point. My biggest issue with a ground probe is that if you have GCFI's and then there's really no reason to use a ground probe. If they trip at such a low amperage then there shouldn't be an issue of tripping them by getting zapped first as someone mentioned earlier.

However, if you can get zapped by tripping a GCFI then I would see how a ground probe could trip it before hand.

My other problem with this argument so far is people keep setting up scenarios like 'you grab your lighting and have your hand in the tank.' I just don't see anyone reaching into their tank with one hand on their lighting.

All I know is electricity is dangerous stuff. I think I'll talk to my old man about this as he's seen his fair share of what can go wrong with electricity.

 

[crustin]

now this was a good thread, no grounding probe in my tank, i have gfi, i have one (grounding probe) in my make up water with a gfi, thanks guys

 

[wlagarde]

Amen - GFCI breakers (not grounding probes) are required by the electrical code in bathrooms, kitchens and outdoor circuits (anywhere there will be water) and it is this way for good reason. I imagine if reef tanks were standard items installed in all homes during their construction they would be required here as well...

 

[ggenz]

if you put your hand in the tank and trip the GFCI(because something is producing electricity), what is the worst that could happen?

small jolt, tingling sensation, and a newer respect for turning off the heater before you dive in or what?

 

[Avast Marine]

My ground probe stays out until I figure a way to hook it up to a voltmeter and be able to visually see if there is current in the tank. My problem is that I don't have any faulty equipment laying around to test this. If I put a 9v battery in a bucket of saltwater do you think it would approximate the "leaking valtage" scenerio?

 

[Avast Marine]

Couldn't find a battery but I did find an old cell phone charger. Output 5v 700ma dc. I plugged it in to my GFCI and dropped the end of the cord into a cup of saltwater......nothing. I thought this would trip the circuit. So I took my $10 voltmeter and put one probe in the water and the other to ground. Read just a little bump on the 1v AC scale but I probably wouldn't notice it if I wasn't looking VERY close. So I put my finger in......tingle, tingle tingle. Hmmm, no trip. Put one probe in the water and the other to the neutral leg and bingo, there was the trip. I tried to trip it again using the same test and it just wouldn't work, to ground or neutral. Hmmm....any thoughts? Just trying to apply the theory's here in a controlled way to possibly find a better or at least agreeable alternative to the ground probe.

 

[Runner]

A battery is DC voltage and would not register on an AC scale. I don't think it would trip a GFCI circuit, either.

I'll give this a try with 120 VAC next time I change some water and see if I can measure the voltage with my multimeter. This is something you definitely should not try on your own. I will be taking multiple saftey measures to ensure I don't kill myself. I've been thinking of putting an indicating light under my tank, anyway. This would be a nice experiment to see if it is worth the effort.


As for sticking your hand in the water and tripping the GFCI, that is relatively safe because of the short duration of the trip. It clears in less that two cycles (<0.025 seconds) in the 20 to 30 mA range (several seconds in the 6 mA range), so the dangerous current typically does not flow long enough to do damage. Again, this is if the GFCI works properly. If I knew there was a fault, I would not rely on it.

 

[Avast Marine]

Thanks Runner, I just would like to move beyond the yes or no question at this point and start trying to develop a better solution.

 

[H20ENG]

Hi Guys,
A great read, here.
I think I have a pretty decent handle on electricity, but Runner, a question for you:
Say you have several GFI circuits (like many of us run) feeding the same tank. If one circuit has a piece of equipment with an electrical "leak", how does it affect the other GFIs? Would each GFI trip, seeing the extra current from the other circuit (maybe only if they were on the same phase? ) How would the GFIs fight it out?
I have run several tanks this way, and have not experienced nuisance tripping that others have reported. I try to keep my stuff clean and in good working order. Maybe its simply a non issue, but the thought crossed my mind.
Thanks!
Chris

 

[Runner]

They have zero effect on each other. Each one senses the currect imbalance on what currect flows through it alone. If you have a GFCI plugged into a GFCI, even then they would just race to see which one trips first.

I still have not tried the water impedence test. I will have my meter home with me this weekend, though.

 

[H20ENG]

Thanks Runner.
Curious about your 120 volt glass of water experiment

We run electrode steam humidifiers that run 60A of 480v through what amounts to a 5g bucket of water. We add salt when we really need to get the RH up