Ground Probe. YES or NO?

MarcF · Jan 27, 2020

I'm interested only in the use of the Ground Probe. I tested my brand new aquarium with brand new pumps and heater with a multimeter and the stray voltage was 18vac. I connected the ground probe and it went to 0. I didn't bother unplugging and plugging these brand new accessories - I just connected the ground probe and the stray voltage went away.
I created a different poll and thread about the GFCI outlet, and there are a lot of comments, and overwhelming support for it, but with some notable and credible dissenters. I have the ground probe and everything plugged into a GFCI outlet, just for the record.
This poll is about the ground probe. Ok if you want to just say, yeah, I have it, why not? but I want to find out from those who really KNOW. I'm in a thread on FB about this and this fellow (probably in this forum as well) says the following:

Anybody who understands electricity doesnt use a ground probe.

Agree or disagree? Let it fly.

LC8Sumi · Jan 27, 2020

Groundprobe ( or = grounded titanium heater):

Without a gfci: you will not know if your equipment is leaking current until it’s high enough to trip your main breaker. (You won’t get shocked most of the time if you touch the water, but this can be misleading* - read about this later, because you could get seriously shocked in certain scenarios)

with a gfci: if it trips, your tank will lose power until you discover and correct it. You won’t get shocked most of the time (that much* - also read about this later).

the second approach sounds better to me & that’s what I do.

ofc with either, there has to be a path from the faulty equipment to the grounding probe/ti heater, and from the socket to an actual proper ground(!) (zeroed before the gfci - at least that’s how it must be done in the EU, don’t know about other places), so if you turn off the return & touch the display water with current in it, you’ll still kill yourself if the probe is in the sump. Okay, that’s a bit of a twist, as the gfci will trip in this case as well - if you have one AND it is installed properly AND working properly. But you’ll still get that >10-30mA through your body for that tiny fraction of time.

*But I hope you see how using a ground probe especially without a gfci (but not exclusively, if the gfci isn’t properly installed or isn’t properly working) might mask a potentially dangerous problem that might surface when you turn off the return and touch the DT, or if the probe fails/disconnects from ground anyhow. If you were not using a probe, chances are that you would discover the problem with a smaller shock before it developes to a bigger, probably lethal issue (that the probe is masking for a while when not being used with a gfci)

with all that said. The salt water tank is an antenna and hence picks up EM waves (induced by radio, cellular, pumps, wavemakers, etc), which have power, altough not much, probably microamps coupled with the volts you see. Measuring the voltage and just the voltage on the tank hence tells nothing useful really, because it might or might not be a faulty piece of equipment causing it. Do not, I repeat, do NOT measure current on the tank even though that would be needed to see the whole picture & conclude if you have a problem or not! Because if you do have a problem and measure the current, the least is you’ll blow fuses & possibly kill your multimeter, but if you’re unlucky enough, you’ll kill yourself as well.

So once again, my advise is to use a grounding probe / grounded titanium heater AND a gfci - that’s the safest approach, with the later being a must and the former not to be used without the later. It would also be a smart idea to ask an electrician to come around once a year and check if all ground connections are working properly in the house.

Notice how a grounded titanium heater without a gfci can be a problem!

LC8Sumi · Jan 27, 2020

Edited the previous comment, so please reread if you did read it before 2020, jan 28. 0:30 UTC

fishguy242 · Jan 27, 2020

more than 1 ,240 have 4 two in tank two in 75 sump

siggy · Jan 27, 2020

Voted no. I do have a new one on hand if needed. I have a titanium heater and will be installing a second one shortly. I do make sure I purchase heaters and power supply's that are grounded if I can, and not just aquarium stuff ALL my tools and equipment.