Grounding Probe?

sundog101 · Nov 10, 2015

Ive read a lot of mixed opinions on grounding probes. Some say they're absolutely necessary while others say to never put them in your tank. What do think? Is it safe to have in a tank?

TheEngineer · Nov 10, 2015

I've never had one personally, but the argument to have one seems like a good one. I don't know what the downside of having it is though. What are the arguments against?

143MPCo · Nov 10, 2015

IMO, a ground probe is only one pieces of a little more complicated issue, you should also consider GFCI and maybe also add the use of an ARC-Fault detector breakers. The recent thread that shown a faulty power-strip that cause a fire MIGHT not have happened IF the wall socket it was plugged into was GFCI.

I ground all my tanks, always have always will but, I also GFCI adapt my outlets and if possible ARC-fault detector breakers, after all you are play with water and electricity, in the right circumstances both can cause great harm add them together and you need to be careful.

I also from time to time test all my systems with a stray voltage detector just to be safe.

TheEngineer · Nov 10, 2015

What @143MPCo said is critically important. All tanks should be on a GFCI. Better to lose some things in your tank than your house. You should also test your GFCIs regularly to ensure they are working properly.

I always considered grounding probes to be more about stray voltage aggravating inhabitants than safety, but they are certainly a layer in that defense. If a pump or heater shorts out, it has a place to go. It would also trip your GFCI.

143MPCo · Nov 10, 2015

icecool2 said:
It would also trip your GFCI.

that's KEY!!
...now you know you have a problem and can start to track it down and ultimately resolve the issue.

saltyphish · Nov 10, 2015

pros of gfci and a grd probe is safety. The cons are if the outlet trips while you are away all power to your tank is gone meaning possible loss in the tank. However, with that being said I believe my family would prefer me to live another day and risk losing my tank unless you have battery back ups.

Windy · Nov 10, 2015

IF you install the ground probe on a switch and disconnect it when you have your hands in the water, they are OK. Otherwise its like strapping a ground band on your wrist ant then touching electrical components. You will be in real trouble if there is a short. You don't see linemen ground themselves before climbing a pole or going into a switch yard.
A GFCI is a safety device. Look at the sellers of ground probes. Look at the packaging. Nowhere will it say the probe is a safety device.

143MPCo · Nov 10, 2015

Not my post but worth share the info...

"Stray voltage in the aquarium can be attributed to causing various problems. Problems such as: finrot, hole-in-the-head disease and numerous others. "

..question is how true is that statement, I've read numerous threads that claimed the effects had to do with lack of grounding and some that said the opposite... so I personally erred on the side of caution and ground all my systems but, would still like to see definitive information in either direction.

I'd also add that I know of a few hobbyist ole-school reefers, that don't employ any grounding devices and have never reported issues as I noted above (finrot, hole-in-the-head disease and numerous others).

Windy · Nov 10, 2015

Your fish may be happy, but you may not be.

TheEngineer · Nov 10, 2015

Windy said:
IF you install the ground probe on a switch and disconnect it when you have your hands in the water, they are OK. Otherwise its like strapping a ground band on your wrist ant then touching electrical components. You will be in real trouble if there is a short. You don't see linemen ground themselves before climbing a pole or going into a switch yard.
A GFCI is a safety device. Look at the sellers of ground probes. Look at the packaging. Nowhere will it say the probe is a safety device.

I'd have to think about this. It seems like a reasonable concern, but I'm not sure it is really a concern. The grounding probe is clearly the path of least resistance and any stray current would want to flow through it. I don't see how you touching the water with a stray voltage and a grounding probe makes you any more susceptible to shock. As to linemen, they don't ground themselves because they would be making themselves a path to ground where one doesn't exist.

I need to think about this more to convince myself one way or the other though...

Windy · Nov 10, 2015

Suppose you have a short in your lights. Put your hand in the grounded water and touch your shorted lights and the current goes through your chest unless you have a GFCI. Put the probe on a switch so when you touch the lights you aren't grounded. Turn the ground probe back on when you are through working on the tank, and you will still get all of the supposed benefits of the probe if any.

Randy Holmes-Farley · Nov 10, 2015

Windy said:
Your fish may be happy, but you may not be.

I see it differently. The primary reason I have a ground probe is because I do not want to be the one who completes the circuit with my body before the GFCI trips. I want the ground probe to trip the GFCI as soon as there is a short. The second reason is I do not want live copper wires (like a broken heater) to be exposed to tank water without tripping a GFCI.

If everything is on a GFCI, as it should be, what scenario is required for a ground probe to make a dangerous situation from a safe one in the absence of a probe? All kinds of electrical devices are gounded on the outside, including a lot of lights. If you are holding a live wire, you need not touch the water to get some current flow (and trip a GFCI, if you have one).

IMO, one of the unprotected scenarios is current flowing out a GFCI outlet, into your body, and back into the same outlet. That won't trip a GFCI, but can shock you, and I have gotten such shocks. Any flow of the current to a ground (including tank water with a ground probe) would trip the GFCI, but without a path to ground, it won't.

TheEngineer · Nov 10, 2015

What @Randy Holmes-Farley said matches my understanding as well. I suppose a scenario could exist where a short occurs while your hands are in the tank. That said, the resistance of the human body is about 1,000Ohms when wet, the resistance of these grounding probes is about 25 Ohms per 1,000 feet (assuming 24 AWG copper wire). There should be no reason for the current to flow through you to find a path to ground. There needs to be a path for it to follow. Unless you are standing barefoot on a wet, metal plate that is grounded there is no path.

The scenario you describe of having your hand in the tank and then touching something that has a short in it is I suppose a chance for this to happen but only if the light is on a separate circuit. If it is on the same GFCI it should trip.

805reef · Nov 10, 2015

This thread was very informative and helpful. I just ordered a grounding probe yesterday but was still on the fence of whether to use it or not. I will be placing it in my tank after reading this thread.

Randy Holmes-Farley · Nov 10, 2015

805reef said:
This thread was very informative and helpful. I just ordered a grounding probe yesterday but was still on the fence of whether to use it or not. I will be placing it in my tank after reading this thread.

Just make sure all devices are on a GFCI.